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6 Best AA & AAA Solar Battery Chargers C, D, NIMH, NICD. Solar aaa battery charger

6 Best AA & AAA Solar Battery Chargers C, D, NIMH, NICD. Solar aaa battery charger

    The Best Portable Solar Chargers of 2023

    Adam has been writing about mobile technology since 2011. He is the former host of the Android Authority podcast, and his work has appeared in numerous publications.

    Rich Scherr is a seasoned technology and financial journalist who spent nearly two decades as the editor of Potomac and Bay Area Tech Wire.

    The best solar chargers use the sun’s abundant power to keep your devices and batteries topped off. Solar chargers aren’t just for nature enthusiasts. Anyone who spends time away from an electrical outlet will find them helpful.

    We recommend the X-DRAGON SunPower Solar Panel Charger for its 40W power output and high-efficiency cells. This charger doesn’t include a power bank to store all that juice, but if you are away from power and need to charge your phone or even your laptop, this is a great option. Opening the eight solar panels will give you plenty of power as long as there’s daylight.

    Best Overall

    X-DRAGON 40W Portable Foldable Solar Panel Charger

    Our best overall charger can produce up to 40W of juice from its eight efficient panels. It opens wide to collect a lot of sunlight with eight high-efficiency panels, but it folds down small enough to fit into your backpack. There’s no water-resistance rating here, so be careful not to get caught in the rain, and no battery is included. But if you have large items that need a charge, the X-DRAGON SunPower Solar Panel Charger is a great choice.

    You can plug in your phone and tablet, but you can also scale that up to your laptop with the five included different-sized barrel chargers and connection for your car battery. This is a great item to keep in your emergency car kit or your backpack for camping. The 18-month warranty will give you peace of mind too.

    Number of Ports: 2 | Power Output: 2.8A max USB, 18V DC | Types of Ports: USB-A, DC | Number of Cells: 8 | Efficiency: 22 to 25% | Battery Capacity: N/A

    Most Portable

    BigBlue 28W Solar Charger

    The Big Blue Solar Charger is a highly-portable solar charging solution that folds to a tiny 11.1 x 6.3 x 1.3 inches when closed. It’s long but narrow and thin, easily fitting into most backpacks. Included carabiners allow you to open and strap it to your bag outdoors.

    There is no built-in battery, but the three USB-A ports allow you to charge any phone or tablet quickly. The panels are waterproof, which our reviewer tested by submerging the cells in a bathtub.

    Our reviewer also noted that the advertised 28W output is misleading. There are four 7W panels which add up to 28 Watts. Unfortunately, the panels could output only around 17W maximum during our testing.

    There’s a pouch for holding cables or devices while charging, which is a nice bonus. Given its water resistance, we’d recommend this for hikers and campers, even in inclement weather. Of course, cloudy days will mean less charging, but at least you know your panels can stand up to it.

    Number of Ports: 3 | Power Output: 5V / 4.8A | Types of Ports: USB-A | Number of Cells: 4 | Efficiency: Not listed | Battery Capacity: N/A

    What to Look for in a Portable Solar Charger

    Water Resistance

    Solar power works best outside, so looking for water resistance in case you unexpectedly get caught in the rain or snow is a good idea.

    Built-in Battery

    Solar panels generate power, and that power has to go somewhere. If you have a solar panel and nothing plugged in, the panels will not generate energy, which is fine, but a battery would allow you to generate power and store it until you need it.

    Power Output

    Keep in mind the kinds of devices you’ll be using. Most solar panels can do the job if all you need to charge is a phone or tablet. If you need to power something larger, such as a laptop or car, you’ll need a powerful setup to get the job done.

    That depends mostly on the cells’ efficiency and the amount of sunlight you’re getting. Solar panels are getting more and more efficient these days, which means they’re capable of generating a lot of power. On a bright, sunny day, it’s not unreasonable to think you can generate enough power for a phone and tablet or even bigger items.

    If it’s big enough, a solar panel can deliver a charge to your car’s battery to allow it to start. A jump start technically means you’re drawing from a power source to start your car right away. The solar option is more of a car battery charger, meaning you’ll need to wait some time for your car’s battery to charge before you can turn the key. But yes, it is possible.

    Solar panels should never be left in a window or in a car to charge. The glass from the window can FOCUS with light on the panels and cause them to overheat. Solar panels are meant to be outside and under the sun, or put away.

    Best AA AAA Solar Battery Chargers [C, D, NIMH, NICD]

    There are tons of battery chargers out there, do you know which ones are solar capable? In this guide, let’s check out the 6 best AA solar battery chargers including ones that can charge AAA, C, D and other battery types.

    Solar battery chargers provide an environmentally friendly, budget-conscious way to reboot an already semi-renewable resource. It sounds techy, but it’s really a simple application that can come in handy for most consumers.

    Best Solar AA Battery Chargers

    Sunway Solar AA AAA Rechargeable Batteries Charger

    • 7-Bay Battery Charger: This charger can charge up to 7 batteries at once. It has six slots for 1.2V batteries including AA/AAA, and a 9V battery slot.
    • 2-Watt Solar Array Lid: The charger has a solar array built right into the lid with the capability of producing up to 2 watts of solar energy. This high wattage allows for fast charging. The panel can even be adjusted to an ideal angle for sunlight absorption by using the handle as a support to tilt the charger.
    • LED Indicators: Sunway has built in LED indicators to alert the user when the battery is fully charged. It also alerts the user if the panel is placed under direct sunlight without a battery in the charger.
    • Durable Construction: Everything about the build of this solar charger leads to increased durability. There are built-in diodes to prevent reverse charging in order to protect the electrical mechanisms of the device. It is also designed with rugged material included strong ABS plastic housing. Users remark that this product is thick, sturdy, and one of the more durable solar chargers on the market.

    C.Crane 11-in-1 Solar Battery Charger

    • 11-Bay Battery Charger: The C.Crane charger is capable of charging 11 different NiCd and NiMH battery sizes including AAA, AA, C, D, and 7 GUM sizes. It can charge up to six batteries at once, but only two of each kind at a time. It is also important to note that charging slows with each additional battery in bay. Users have noted that while this charger is capable of charging in array of battery sizes, it works most efficiently when charging AA and AAA batteries.
    • Adjustable Solar Array Lid: The battery charger has a 150 mAh solar array built into the lid. The lid is adjustable, and the charger comes equipped with a kickstand to allow for optimal sun exposure. The low amperage of this device means slow charging; however the diverse charging capabilities and many battery bays make this a great choice for charging backup battery sets, especially during an emergency situation.
    • Built-in Meter: A built-in meter tells the user the current strength of the sun, the current out-put from the solar panel, and the time required to charge different types of batteries.
    • Weather Resistant: A polycarbonate transparent cover makes this device durable and weather resistant.

    GoldMaster Solar Powered Battery Charger

    • 4-Bay Battery Charger: The GoldMaster solar battery charger can charge four batteries at a time- AA, AAA, C, or D.
    • Adjustable Solar Array Lid: This product comes with solar cells built into the lid. The lid can be tilted for optimal light absorption. The manufacturer does not provide the wattage of the panel. While official product reviews state that it can charge four batteries of the same types in about five hours, consumer reviews state that this device is more akin to a trickle charger than a standard battery charger and report longer charge times.
    • USB and Various Charging Plugs: This solar panel can do more than power up your AA batteries, it can also directly charge your devices. The built-in USB charging port is compatible with most cell phones and cameras. The device also has various other charging plugs for charging a variety of electronics and devices.
    • Indoor/Outdoor Use: This panel is built with weather resistant housing to allow for safe outdoor use. But unlike many other solar battery chargers, it can also be used indoors. Bright sunlight is not necessary for this panel to work, and it can still produce adequate energy when placed indoors at a south-facing window.

    UltraLast Green AA Solar Powered Battery Charger

    • Built in Solar Array: This solar charger comes equipped with a built in 2100 mAh solar array to allow for fast battery charging of two included batteries.
    • Portability: The rugged, compact cover and ultra-light weight make this solar battery charger great for portability. The device weighs only 1 pound, about half that of the competing chargers on this list. It comes with a clip to attach to backpacks, tents, or clothing and a kickstand to help with angling the panel for optimal light absorption.
    • Multi-Use USB Port: Option to charge batteries via USB port when sunlight is not accessible. The port can also be used to charge external electronic devices off the fully charged batteries.
    • LED Indicator: LED lights tell you charging direction (battery receiving power from solar or USB/ electronic device receiving power from solar/USB).
    • BONUS! Eco-Friendly Packaging: Packaging includes post-consumer recycled cardboard and recyclable PET plastic.

    Best Solar Compatible AA Battery Chargers

    These USB battery chargers do not have solar panels built in, but are capable of being powered by a solar panel. This gives not only gives you multiple charging options, but also gives you the ability to pull from a higher wattage solar panel.

    EBL iQuick Smart Battery Charger

    • 4-Bay Battery Charger: the iQuick Charger has 4 individual bays for charging 1/2/3/4 AA/AAA Ni-MH batteries.
    • Smart Charger Safety Assurance: An advanced MCU control system enables automatic cut-off charging to prevent over charging batteries, automatic trickle charging mode, and over-current and over-heat protection.
    • Includes High-Performance Batteries: This charger comes with 4- AA 2300mAh batteries. These are low self-discharge batteries which reserve 85% power when left sitting for up to one year. These batteries can be fully recharged in the Smart charger in 40 minutes.
    • Solar-Compatible: While this product does not have a solar array built in, it is solar capable. There USB port where the wall charger plugs in can be used to attach a solar panel of your choosing.

    Goal Zero Guide 10 Plus Recharger

    • 4-Bay Battery Charger: The Goal Zero Guide 10 has the ability to charge 4-AA or 4-AAA batteries at once.
    • Multi-Use USB Port: A USB port allows for external wall charging. It also allows the user to connect external devices for charging. According to Goal Zero, with four fully charged batteries inserted, the device can recharge your Smart phone 1-3 times.
    • Compact and Light-Weight: This device weighs only 6.3 ounces and is sized at 3.94 X 2.52 X.75 in. This makes it the smallest device reviewed today. It is important to remember, however, that this does not include the solar array.
    • Solar Kit Available: Goal Zero also sells this charger in a solar kit which includes the solar charger, the 2300 mAh Nomad 7 Solar panel, 4-AA batteries, a AAA battery insert, and a removable pouch and kickstand.

    Buyer’s Guide

    What can you use rechargeable batteries for, and why should you use a solar charger to reboot them? We take an in depth look at these common questions below.

    How Does It Work?

    Using photovoltaic rays from the sun, the PV glass converts light into energy. This is then transferred into your AA, AAA, C, D, and other batteries to be used in your favorite devices. Simply put the batteries in the charging bay and place the device somewhere sunny. Within mere hours, your batteries will be good as new again.

    Types Of Rechargeable Batteries

    • Primary cell batteries. Alkaline disposable batteries
    • Secondary cell batteries. Rechargeable batteries

    Rechargeable batteries include:

    • NIMH (AAA AA). Better choice for general purpose use
    • NICD (AAA AA). Good for high temperature applications
    • LiPo
    • NiFe

    They come in a variety of sizes including AA, AAA, C, D. These batteries have the capability to restore their energy capacity with the aid of an electrical current provided by a charger.

    Rechargeable batteries are used in every day applications spanning from your cell phone to your automobile. They can last up to 200 charging cycles, making them both convenient for the user and responsible for the environment.

    Why Use a Solar Charger?

    The main reason people are drawn to solar chargers is location freedom. The ability to use the sun as a power source means you don’t have to be tied to the power grid. This is great for remote homes and worksites as well as nature enthusiasts including those that enjoy hiking, camping, and boating.

    There are other less obvious scenarios where on the go charging may come handy too. For example, students can benefit from solar charging by attaching a solar panel to their backpack. While walking to class or lounging in the quad between classes, battery powered devices can be rebooting.

    Another reason to choose a solar device to power up your rechargeable batteries is the application’s decreased impact on our current environmental crises. Solar cells generate no emissions, waste, or byproducts during use. Many people may not realize the implications that come with using modern day electricity.

    The act of plugging a charger into the wall seems like such a small and harmless act. However, in a study done in 2018 it was found that 6.4 megatons of greenhouse gases were emitted in a single year from cell phone charging alone, and that number is growing immensely year by year.

    By 2040, it is predicted that 14% of our global footprint will come from societal communications and information technology such as our laptops, Smart phones, and tablets.

    Who Can Benefit from Using a Solar Charger for AA, AAA, D Cell, NIMH, NICD Batteries?

    Anyone that uses a device charged by a secondary cell battery can benefit from investing in solar battery charger.

    Devices that use the batteries listed above include flashlights and other light sources, portable radios, walkies, toys, shavers, torches, remote controls, cameras, wireless keyboards, and other digital devices.

    I personally use rechargeable batteries for a portable keyboard so that I can play music in the park and while camping!

    If you are interested in using rechargeable batteries for light sources, check out our article on the best AA Batteries for Solar Light for more information.

    Is Using a Solar Battery Charger for AA Batteries Really Necessary?

    It isn’t necessary to use a solar battery charger for AA batteries. Plugging into a wall charger is an easy alternative.

    However this does come with the standard drawbacks of tying into the power grid. These drawbacks include high costs, location restrictions, susceptibility to outages, and negative environmental impacts.


    As with any new venture, it is best to be well informed before getting started. While recharging batteries is a simple hands-off process, there are still a few safety precautions you should keep in mind.

    What to Be Aware of When Charging These Batteries

    Rechargeable batteries can be easily damaged if they are not charged properly. Always make sure to use a cord and charger compatible with the battery. Additionally, make sure the battery is compatible with device you wish to power.

    To avoid overheating and prevent fire hazards during charging, place the battery charger on a non-flammable surface with good air circulation around the device.

    It is also imperative to be sure that a battery is in fact rechargeable before trying to recharge it. Charging a disposable battery can lead to a break in the battery seal causing the battery to leak severely hazardous chemicals or even explode or burst into flames.

    Lastly, safety measures should continue even after the battery has reached the end of its final lifecycle. Batteries are not biodegradable and can be quite toxic.

    It is important to properly recycle your used batteries so that they do not end up in a landfill. Most towns have centers that will accept used batteries for recycling.

    How to Tell If a Battery Is Made to Be Recharged?

    One way to tell if a battery is rechargeable is to check the voltage. A standard disposable battery has a voltage of 1.5.

    In comparison, a typical rechargeable battery has a voltage of 1.2. However, this test is not fool proof. A standard battery loses efficiency over time. At first use it will carry a voltage of 1.5V, reducing to about 1.0V by the end of its lifetime.

    A reading of 1.2V in the middle stages of a disposable battery’s life cycle is possible, therefore this test should be administered at first use to ensure accuracy.

    Wrap up

    As shown above, different solar chargers work better for different needs. Features include number and type of battery bays, wattage of built-in solar arrays, durability, and more.

    All of the solar battery chargers detailed above will work great for emergency kits, hiking equipment, or a fun-filled day at the park.

    Have you tried one of these devices? Be sure to reach out and share your experience with us!

    Simple Solar Battery Charger Circuits

    Simple solar charger are small devices which allow you to charge a battery quickly and cheaply, through solar energy.

    A simple solar charger must have 3 basic features built-in:

    • It should be low cost.
    • Layman friendly, and easy to build.
    • Must be efficient enough to satisfy the fundamental battery charging needs.

    The post comprehensively explains nine best yet simple solar battery charger circuits using the IC LM338, transistors, MOSFET, buck converter, etc which can be built and installed even by a layman for charging all types of batteries and operating other related equipment


    Solar panels are not new to us and today it’s being employed extensively in all sectors. The main property of this device to convert solar energy to electrical energy has made it very popular and now it’s being strongly considered as the future solution for all electrical power crisis or shortages.

    Solar energy may be used directly for powering an electrical equipment or simply stored in an appropriate storage device for later use.

    Normally there’s only one efficient way of storing electrical power, and it’s by using rechargeable batteries.

    Rechargeable batteries are probably the best and the most efficient way of collecting or storing electrical energy for later usage.

    The energy from a solar cell or a solar panel can also be effectively stored so that it can be used as per ones own preference, normally after the sun has set or when it’s dark and when the stored power becomes much needed for operating the lights.

    Though it might look quite simple, charging a battery from a solar panel is never easy, because of two reasons:

    The voltage from a solar panel can vary hugely, depending upon the incident sun rays, and

    The current also varies due to the same above reasons.

    The above two reason can make the charging parameters of a typical rechargeable battery very unpredictable and dangerous.

    Before delving into the following concepts you can probably try this super easy solar battery charger which will ensure safe and guaranteed charging of a small 12V 7 Ah battery through a small solar panel:

    • Solar Panel. 20V, 1 amp
    • IC 7812. 1no
    • 1N4007 Diodes. 3nos
    • 2k2 1/4 watt resistor. 1no

    That looks cool isn’t it. In fact the IC and the diodes could already resting in your electronic junk box, so need of buying them. Now let’s see how these can be configured for the final outcome.

    As we know the IC 7812 will produce a fixed 12V at the output which cannot be used for charging a 12V battery. The 3 diodes connected at its ground (GND) terminals is introduced specifically to counter this problem, and to upgrade the IC output to about 12 0.7 0.7 0.7 V = 14.1 V, which is exactly what is required for charging a 12 V battery fully.

    The drop of 0.7 V across each diodes raises the grounding threshold of the IC by stipulated level forcing the IC to regulate the output at 14.1 V instead of 12 V. The 2k2 resistor is used to activate or bias the diodes so that it can conduct and enforce the intended 2.1 V total drop.

    Making it Even Simpler

    If you are looking for an even simpler solar charger, then probably there cannot be anything more straightforward than connecting an appropriately rated solar panel directly with the matching battery via a blocking diode, as shown below:

    Although, the above design does not incorporate a regulator, it will still work since the panel current output is nominal, and this value will only show a deterioration as the sun changes its position.

    However, for a battery that is not fully discharged, the above simple set up may cause some harm to the battery, since the battery will tend to get charged quickly, and will continue to get charged to unsafe levels and for longer periods of time.

    You may also like this Highly Efficient 0-50V Solar Charger Circuit

    ) Using LM338 as Solar Controller

    But thanks to the modern highly versatile chips like the LM 338 and LM 317, which can handle the above situations very effectively, making the charging process of all rechargeable batteries through a solar panel very safe and desirable.

    The circuit of a simple LM338 solar battery charger is shown below, using the IC LM338:

    The circuit diagram shows a simple set up using the IC LM 338 which has been configured in its standard regulated power supply mode.

    Using a Current Control Feature

    The specialty of the design is that it incorporates a current control feature also.

    It means that, if the current tends to increase at the input, which might normally take place when the sun ray intensity increases proportionately, the voltage of the charger drops proportionately, pulling down the current back to the specified rating.

    As we can see in the diagram, the collector/emitter of the transistor BC547 is connected across the ADJ and the ground, it becomes responsible for initiating the current control actions.

    As the input current rises, the battery starts drawing more current, this build up a voltage across R3 which is translated into a corresponding base drive for the transistor.

    The transistor conducts and corrects the voltage via the C LM338, so that the current rate gets adjusted as per the safe requirements of the battery.

    Current Limit Formula:

    R3 may be calculated with the following formula

    PCB Design for the above explained simple solar battery charger circuit is given below:

    The meter and the input diode are not included in the PCB.

    ) 1 Solar Battery Charger Circuit

    The second design explains a cheap yet effective, less than 1 cheap yet effective solar charger circuit, which can be built even by a layman for harnessing efficient solar battery charging.

    You will need just a solar panel panel, a selector switch and some diodes for getting a reasonably effective solar charger set up.

    What is Maximum Power Point Solar Tracking?

    For a layman this would be something too complex and sophisticated to grasp and a system involving extreme electronics.

    In a way it may be true and surely MPPTs are sophisticated high end devices which are meant for optimizing the charging of the battery without altering the solar panel V/I curve.

    In simple words an MPPT tracks the instantaneous maximum available voltage from the solar panel and adjusts the charging rate of the battery such that the panel voltage remains unaffected or away from loading.

    Put simply, a solar panel would work most efficiently if its maximum instantaneous voltage is not dragged down close to the connected battery voltage, which is being charged.

    For example, if the open circuit voltage of your solar panel is 20V and the battery to be charged is rated at 12V, and if you connect the two directly would cause the panel voltage to drop to the battery voltage, which would make things too inefficient.

    Conversely if you could keep the panel voltage unaltered yet extract the best possible charging option from it, would make the system work with MPPT principle.

    So it’s all about charging the battery optimally without affecting or dropping the panel voltage.

    There’s one simple and zero cost method of implementing the above conditions.

    Choose a solar panel whose open circuit voltage matches the battery charging voltage. Meaning for a 12V battery you may choose a panel with 15V and that would produce maximum optimization of both the parameters.

    However practically the above conditions could be difficult to achieve because solar panels never produce constant outputs, and tend to generate deteriorating power levels in response to varying sun ray positions.

    That’s why always a much higher rated solar panel is recommended so that even under worse day time conditions it keeps the battery charging.

    Having said that, by no means it is necessary to go for expensive MPPT systems, you can get similar results by spending a few bucks for it. The following discussion will make the procedures clear.

    How the Circuit Works

    As discussed above, in order to avoid unnecessary loading of the panel we need to have conditions ideally matching the PV voltage with the battery voltage.

    This can be done by using a few diodes, a cheap voltmeter or your existing multimeter and a rotary switch. Ofcourse at around 1 you cannot expect it to be automatic, you may have to work with the switch quite a few times each day.

    We know that a rectifier diode’s forward voltage drop is around 0.6 volts, so by adding many diodes in series it can be possible to isolate the panel from getting dragged to the connected battery voltage.

    Referring to the circuit digaram given below, a cool little MPPT charger can be arranged using the shown cheap components.

    Let’s assume in the diagram, the panel open circuit voltage to be 20V and the battery to be rated at 12V.

    Connecting them directly would drag the panel voltage to the battery level making things inappropriate.

    By adding 9 diodes in series we effectively isolate the panel from getting loaded and dragged to the battery voltage and yet extract the Maximum charging current from it.

    The total forward drop of the combined diodes would be around 5V, plus battery charging voltage 14.4V gives around 20V, meaning once connected with all the diodes in series during peak sunshine, the panel voltage would drop marginally to may be around 19V resulting an efficient charging of the battery.

    Now suppose the sun begins dipping, causing the panel voltage to drop below the rated voltage, this can be monitored across the connected voltmeter, and a few diodes skipped until the battery is restored with receiving optimal power.

    The arrow symbol shown connected with the panel voltage positive can be replaced with a rotary switched for the recommended selection of the diodes in series.

    With the above situation implemented, a clear MPPT charging conditions can be simulated effectively without employing costly devices. You can do this for all types of panels and batteries just by including more number of diodes in series.

    ) Solar Charger and Driver Circuit for 10W/20W/30W/50W White High Power SMD LED

    The 3rd idea teaches us how to build a simple solar LED with battery charger circuit for illuminating high power LED (SMD) lights in the order of 10 watt to 50 watt. The SMD LEDs are fully safeguarded thermally and from over current using an inexpensive LM 338 current limiter stage. The idea was requested by Mr. Sarfraz Ahmad.

    Technical Specifications

    Basically I am a certified mechanical engineer from Germany 35 years ago and worked overseas for many years and left many years ago due to personal problems back home.Sorry to bother you but I know about your capabilities and expertise in electronics and sincerity to help and guide the beginnings like me.I have seen this circuit some where for 12 vdc.

    I have attached to SMD ,12v 10 watt, cap 1000uf,16 volt and a bridge rectifier you can see the part number on that.When I turn the lights on the rectifier starts to heat up and the both SMDs as well. I am afraid if these lights are left on for a long time it may damage the SMDs and rectifier. I don not know where the problem is. You may help me.

    I have a light in car porch which turns on at disk and off at dawn. Unfortunately due to load shedding when there is no electricity this light remains off till the electricity is back.

    I want to install at least two SMD (12 volt) with LDR so as soon the light turns off the SMD lights will turn on. I want to additional two similar light elsewhere in the car porch to keep the entire are lighted.I think that if I connect all these four SMD lights with 12 volt power supply which will get the power from UPS circuit.

    Of course it will put additional load on UPS battery which is hardly fully charged due to frequent load shedding. The other best solution is to install 12 volt solar panel and attach all these four SMD lights with it. It will charge the battery and will turn the lights On/OFF.

    This solar panel should be capable to keeps these lights all the night and will turn OFF at dawn.Please also help me and give details about this circuit/project.

    You may take your time to figure out how to do that.I am writing to you as unfortunately no electronics or solar product seller in our local market is willing to give me any help, None of them seems to be technical qualified and they just want to sell their parts.

    The Design

    In the shown 10 watt to 50 watt SMD solar LED light circuit with automatic charger above, we see the following stages:

    • A solar panel
    • A couple of current controlled LM338 regulator circuits
    • A changeover relay
    • A rechargeable battery
    • and a 40 watt LED SMD module

    The above stages are integrated in the following explained manner:

    The two LM 338 stages are configured in standard current regulator modes with using the respective current sensing resistances for ensuring a current controlled output for the relevant connected load.

    The load for the left LM338 is the battery which is charged from this LM338 stage and a solar panel input source. The resistor Rx is calculated such that the battery receives the stipulated amount of current and is not over driven or over charged.

    The right side LM 338 is loaded with the LED module and here too the Ry makes sure that module is supplied with the correct specified amount of current in order to safeguard the devices from a thermal runaway situation.

    The solar panel voltage specs may be anywhere between 18V and 24V.

    A relay is introduced in the circuit and is wired with the LED module such that it’s switched ON only during the night or when it’s dark below threshold for the solar panel to generate the required any power.

    As long as the solar voltage is available, the relay stays energized isolating the LED module from the battery and ensuring that the 40 watt LED module remains shut off during day time and while the battery is being charged.

    After dusk, when the solar voltage becomes sufficiently low, the relay is no longer able to hold its N/O position and flips to the N/C changeover, connecting the battery with the LED module, and illuminating the array through the available fully charged battery power.

    The LED module can be seen attached with a heatsink which must be sufficiently large in order to achieve an optimal outcome from the module and for ensuring longer life and brightness from the device.

    Calculating the Resistor Values

    The indicated limiting resistors may be calculated from the given formulas:

    Rx = 1.25/battery charging current

    Ry = 1.25/LED current rating.

    Assuming the battery to be a 40 AH lead acid battery, the preferred charging current should be 4 amps.

    therefore Rx = 1.25/4 = 0.31 ohms

    wattage = 1.25 x 4 = 5 watts

    The LED current can be found by dividing its total wattage by the voltage rating, that is 40/12 = 3.3amps

    therefore Ry = 1.25/3 = 0.4 ohms

    wattage = 1.25 x 3 = 3.75 watts or 4 watts.

    Limiting resistors are not employed for the 10 watt LEDs since the input voltage from the battery is on par with the specified 12V limit of the LED module and therefore cannot exceed the safe limits.

    The above explanation reveals how the IC LM338 can be simply used for making an useful solar LED light circuit with an automatic charger.

    ) Automatic Solar Light Circuit using a Relay

    In our 4rth automatic solar light circuit we incorporate a single relay as a switch for charging a battery during day time or as long as the solar panel is generating electricity, and for illuminating a connected LED while the panel is not active.

    Upgrading to a Relay Changeover

    In one of my previous article which explained a simple solar garden light circuit, we employed a single transistor for the switching operation.

    One disadvantage of the earlier circuit is, it does not provide a regulated charging for the battery, although it not might be strictly essential since the battery is never charged to its full potential, this aspect might require an improvement.

    Another associated disadvantage of the earlier circuit is its low power spec which restricts it from using high power batteries and LEDs.

    The following circuit effectively solves both the above two issues, with the help of a relay and a emitter follower transistor stage.

    How it Works

    During optimal sun shine, the relay gets sufficient power from the panel and remains switched ON with its N/O contacts activated.

    This enables the battery to get the charging voltage through a transistor emitter follower voltage regulator.

    The emitter follower design is configured using a TIP122, a resistor and a zener diode. The resistor provides the necessary biasing for the transistor to conduct, while the zener diode value clamps the emitter voltage is controlled at just below the zener voltage value.

    The zener value is therefore appropriately chosen to match the charging voltage of the connected battery.

    For a 6V battery the zener voltage could be selected as 7.5V, for 12V battery the zener voltage could be around 15V and so on.

    The emitter follower also makes sure that the battery is never allowed to get overcharged above the allocated charging limit.

    During evening, when a substantial drop in sunlight is detected, the relay is inhibited from the required minimum holding voltage, causing it to shift from its N/O to N/C contact.

    The above relay changeover instantly reverts the battery from charging mode to the LED mode, illuminating the LED through the battery voltage.

    Parts list for a 6V/4AH automatic solar light circuit using a relay changeover

    • Solar Panel = 9V, 1amp
    • Relay = 6V/200mA
    • Rx = 10 ohm/2 watt
    • zener diode = 7.5V, 1/2 watt

    ) Transistorized Solar Charger Controller Circuit

    The fifth idea presented below details a simple solar charger circuit with automatic cut-off using transistors only. The idea was requested by Mr. Mubarak Idris.

    Circuit Objectives and Requirements

    • Please sir can you make me a 12v, 28.8AH lithium ion battery,automatic charge controller using solar panel as a supply, which is 17v at 4.5A at max sun light.
    • The charge controller should be able to have over charge protection and low battery cut off and the circuit should be simple to do for beginner without ic or micro controller.
    • The circuit should use relay or bjt transistors as a switch and zener for voltage reference thanks sir hope to hear from you soon!

    The Design

    PCB Design (Component Side)

    Referring to the above simple solar charger circuit using transistors, the automatic cut off for the full charge charge level and the lower level is done through a couple of BJTs configured as comparators.

    Recall the earlier low battery indicator circuit using transistors, where the low battery level was indicated using just two transistors and a few other passive components.

    Here we employ an identical design for the sensing of the battery levels and for enforcing the required switching of the battery across the solar panel and the connected load.

    Let’s assume initially we have a partially discharged battery which causes the first BC547 from left to stop conducting (this is set by adjusting the base preset to this threshold limit), and allows the next BC547 to conduct.

    When this BC547 conducts it enable the TIP127 to switch ON, which in turn allows the solar panel voltage to reach the battery and begin charging it.

    The above situation conversely keeps the TIP122 switched OFF so that the load is unable to operate.

    As the battery begins getting charged, the voltage across the supply rails also begin rising until a point where the left side BC547 is just able to conduct, causing the right side BC547 to stop conducting any further.

    As soon as this happens, the TIP127 is inhibited from the negative base signals and it gradually stops conducting such that the battery gradually gets cut off from the solar panel voltage.

    However, the above situation permits the TIP122 to slowly receive a base biasing trigger and it begins conducting. which ensures that the load now is able to get the required supply for its operations.

    The above explained solar charger circuit using transistors and with auto cut-offs can be used for any small scale solar controller applications such as for charging cellphone batteries or other forms of Li-ion batteries safely.

    For getting a Regulated Charging Supply

    The following design shows how to convert or upgrade the above circuit diagram into a regulated charger, so that the battery is supplied with a fixed and a stabilized output regardless of a rising voltage from the solar panel.

    The above designs can be further simplified, as shown in the following over-charge, over-discharge solar battery controller circuit:

    Here, the zener ZX decides the full charge battery cut off, and can be calculated using the following formula:

    ZX = Battery full charge value 0.6

    For example, if the full-charge battery level is 14.2V, then the ZX can be 14 0.6 = 14.6V zener which can be built by adding a few zener diodes in series, along with a few 1N4148 diodes, if required.

    The zener diode ZY decides the battery over-discharge cut off point, and can be simply equal to the value of the desired low battery value.

    For example if the minimum low battery level is 11V, then the ZY can be selected to be a 11V zener.

    The above design can be also integrated with an LM338 charger circuit as shown below:

    ) Solar LED Light Circuit

    The sixth design here explains a simple low cost solar LED light circuit which could be used by the needy and, underprivileged section of the society for illuminating their houses at night cheaply.

    The idea was requested by Mr. R.K. Rao

    Circuit Objectives and Requirements

    • I want to make a SOLAR LED light using a 9cm x 5cm x 3cm transparent plastic box [available in the market for Rs.3/-] using a one watt LED/20mA LEDS powered by a 4v 1A rechargeable sealed lead-acid battery [SUNCA/VICTARI] also with a provision for charging with a cell phone charger [where grid current is available].
    • The battery should be replaceable when dead after use for 2/3 years/prescribed life by the rural/tribal user.
    • This is meant for use by tribal/rural children to light up a book; there are better led lights in the market for around Rs.500 [d.light],for Rs.200 [Thrive].
    • These lights are good except that they have a mini solar panel and a bright LED with a life of ten years if not more ,but with a rechargeable battery without a provision for its replacement when dead after two or three years of use.It is a waste of resource and unethical.
    • The project i am envisaging is one in which the battery can be replaced. be locally available at low cost. The price of the light should not exceed Rs.100/150.
    • It will be marketed on not for profit basis through NGOs in tribal areas and ultimately supply kits to tribal/rural youth to make them in the village.
    • I along with a colleague have made some lights with 7V EW high power batteries and 2x20mA pirahna Leds and tested them-they lasted for over 30 hours of continuous lighting adequate to light up a book from half-meter distance; and another with a 4v sunce battery and 1watt 350A LED giving enough light for cooking in a hut.
    • Can you suggest a circuit with a one AA/AAA rechargeable battery,mini solar panel to fit on the box cover of 9x5cm and a DC-DC booster and 20mA leds. If you want me to come over to your place for discussions i can.
    • You can see the lights we have made in google photos at Thanking you,

    The Design

    As per the request the solar LED light circuits needs to be compact, work with a single 1.5AAA cell using a DC-DC converter and equipped with a self regulating solar charger circuit.

    The circuit diagram shown below probably satisfies all the above specifications and yet stays within the affordable limit.

    Circuit Diagram

    The design is a basic joule thief circuit using a single penlight cell, a BJT and an inductor for powering any standard 3.3V LED.

    In the design a 1 watt LeD is shown although a smaller 30mA high bright LED could be used.

    The solar LED circuit is capable squeezing out the last drop of joule or the charge from the cell and hence the name joule thief, which also implies that the LED would keep illuminated until there’s virtually nothing left inside the cell. However the cell here being a rechargeable type is not recommended to be discharged below 1V.

    The 1.5V battery charger in the design is built using another low power BJT configured in its emitter follower configuration, which allows it to produce an emitter voltage output that’s exactly equal to the potential at its base, set by the 1K preset. This must be precisely set such that the emitter produces not more than 1.8V with a DC input of above 3V.

    The DC input source is a solar panel which may be capable of producing an excess of 3V during optimal sunlight, and allow the charger to charge the battery with a maximum of 1.8V output.

    Once this level is reached the emitter follower simply inhibits any further charging of the cell thus preventing any possibility of an over charge.

    The inductor for the solar LED light circuit consists of a small ferrite ring transformer having 20:20 turns which could be appropriately altered and optimized for enabling the most favorable voltage for the connected LED which may last even until the voltage has fallen below 1.2V.

    ) Simple Solar Charger for Street Lights

    The seventh solar charger discussed here is best suited as a solar LED street light system is specifically designed for the new hobbyist who can build it simply by referring to the pictorial schematic presented here.

    Due to its straightforward and relatively cheaper design the system can be suitably used for village street lighting or in other similar remote areas, nonetheless this by no means restricts it from being used in cities also.

    Main Features of this system are:

    1) Voltage controlled Charging

    2) Current Controlled LED Operation

    3) No Relays used, all Solid-State Design

    4) Low Critical Voltage Load Cut-off

    5) Low Voltage and Critical Voltage Indicators

    6) Full Charge cut-off is not included for simplicity sake and because the charging is restricted to a controlled level which will never allow the battery to over-charge.

    7) Use of popular ICs like LM338 and transistors like BC547 ensure hassle free procurement

    8) Day night sensing stage ensuring automatic switch OFF at dusk and switch ON at dawn.

    The entire circuit design of the proposed simple LED street light system is illustrated below:

    Circuit Diagram

    The circuit stage comprising T1, T2, and P1 are configured into a simple low battery sensor, indicator circuit

    An exactly identical stage can also be seen just below, using T3, T4 and the associated parts, which form another low voltage detector stage.

    The T1, T2 stage detects the battery voltage when it drops to 13V by illuminating the attached LED at the collector of T2, while the T3, T4 stage detects the battery voltage when it reaches below 11V, and indicates the situation by illuminating the LED associated with the collector of T4.

    P1 is used for adjusting the T1/T2 stage such that the T2 LED just illuminates at 12V, similarly P2 is adjusted to make the T4 LED begin illuminating at voltages below 11V.

    IC1 LM338 is configured as a simple regulated voltage power supply for regulating the solar panel voltage to a precise 14V, this is done by adjusting the preset P3 appropriately.

    This output from IC1 is used for charging the street lamp battery during day time and peak sunshine.

    IC2 is another LM338 IC, wired in a current controller mode, its input pin is connected with the battery positive while the output is connected with the LED module.

    IC2 restricts the current level from the battery and supplies the right amount of current to the LED module so that it is able operate safely during night time back up mode.

    T5 is a power transistor which acts like a switch and is triggered by the critical low battery stage, whenever the battery voltage tends to reach the critical level.

    Whenever this happens the base of T5 is instantly grounded by T4, shutting it off instantly. With T5 shut off, the LED module is enable to illuminate and therefore it is also shut off.

    This condition prevents and safeguards the battery from getting overly discharged and damaged. In such situations the battery might need an external charging from mains using a 24V, power supply applied across the solar panel supply lines, across the cathode of D1 and ground.

    The current from this supply could be specified at around 20% of battery AH, and the battery may be charged until both the LEDs stop glowing.

    The T6 transistor along with its base resistors is positioned to detect the supply from the solar panel and ensure that the LED module remains disabled as long as a reasonable amount of supply is available from the panel, or in other words T6 keeps the LED module shut off until its dark enough for the LED module and then is switched ON. The opposite happen at dawn when the LED module is automatically switched OFF. R12, R13 should be carefully adjusted or selected to determine the desired thresholds for the LED module’s ON/OFF cycles

    How to Build

    To complete this simple street light system successfully, the explained stages must be built separately and verified separately before integrating them together.

    First assemble the T1, T2 stage along with R1, R2, R3, R4, P1 and the LED.

    Next, using a variable power supply, apply a precise 13V to this T1, T2 stage, and adjust P1 such that the LED just illuminates, increase the supply a bit to say 13.5V and the LED should shut off. This test will confirm the correct working of this low voltage indicator stage.

    Identically make the T3/T4 stage and set P2 in a similar fashion to enable the LED to glow at 11V which becomes the critical level setting for the stage.

    After this you can go ahead with the IC1 stage, and adjust the voltage across its body and ground to 14V by adjusting P3 to the correct extent. This should be again done by feeding a 20V or 24V supply across its input pin and ground line.

    The IC2 stage can be built as shown and will not require any setting up procedure except the selection of R11 which may be done using the formula as expressed in this universal current limiter article

    Parts List

    • R1, R2, R3 R4, R5, R6, R7 R8, R9, R12 = 10k, 1/4 WATT
    • P1, P2, P3 = 10K PRESETS
    • R10 = 240 OHMS 1/4 WATT
    • R13 = 22K
    • D1, D3 = 6A4 DIODE
    • D2, D4 = 1N4007
    • T1, T2, T3, T4 = BC547
    • T5 = TIP142
    • R11 = SEE TEXT
    • IC1, IC2 = LM338 IC TO3 package
    • LED Module = Made by connecting 24nos 1 WATT LEDs in series and parallel connections
    • Battery = 12V SMF, 40 AH
    • Solar Panel = 20/24V, 7 Amp

    Making th 24 watt LED Module

    The 24 watt LED module for the above simple solar street light system could be built simply by joining 24 nos 1 watt LEDs as shown in the following image:

    ) Solar Panel Buck Converter Circuit with Over Load Protection

    The 8th solar concept discussed below talks about a simple solar panel buck converter circuit which can be used to obtain any desired low bucked voltage from 40 to 60V inputs. The circuit ensures a very efficient voltage conversions. The idea was requested by Mr. Deepak.

    Technical Specifications

    I am looking for DC. DC buck converter with following features.

    Input voltage = 40 to 60 VDC

    Output voltage = Regulated 12, 18 and 24 VDC (multiple output from the same circuit is not required. Separate circuit for each o/p voltage is also fine)

    Output current capacity = 5-10A

    Protection at output = Over current, short circuits etc.

    Small LED indicator for unit operation would be an advantage.

    Appreciate if you could help me designing the circuit.

    Best regards, Deepak

    The Design

    The proposed 60V to 12V, 24V buck converter circuit is shown in the figure below, the details may be understood as explained below:

    The configuration could be divided into stages, viz. the astable multivibrator stage and the mosfet controlled buck converter stage.

    BJT T1, T2 along with its associated parts forms a standard AMV circuit wired to generate a frequency at the rate of about 20 to 50kHz.

    Mosfet Q1 along with L1 and D1 forms a standard buck converter topology for implementing the required buck voltage across C4.

    The AMV is operated by the input 40V and the generated frequency is fed to the gate of the attached mosfet which instantly begins oscillating at the available current from the input driving L1, D1 network.

    The above action generates the required bucked voltage across C4,

    D2 makes sure that this voltage never exceeds the rated mark which may be fixed 30V.

    This 30V max limit bucked voltage is further fed to a LM396 voltage regulator which may be set for getting the final desired voltage at the output at the rate of 10amps maximum.

    The output may be used for charging the intended battery.

    Parts List for the above 60V input, 12V, 24V output buck converter solar for the panels.

    • R1-R5 = 10K
    • R6 = 240 OHMS
    • R7 = 10K POT
    • C1, C2 = 2nF
    • C3 = 100uF/100V
    • C4 = 100uF/50V
    • Q1 = ANY 100V, 20AMP P-channel MOSFET
    • T1,T2 = BC546
    • D2 = 30V ZENER 1 WATT
    • D3 = 1N4007
    • L1 = 30 turns of 21 SWG super enameled copper wire wound over a 10mm dia ferrite rod.

    ) Home Solar Electricity Set up for an Off-the-grid Living

    The ninth unique design explained here illustrates a simple calculated configuration which may be used for implementing any desired sized solar panel electricity set up for remotely located houses or for achieving an off the grid electricity system from solar panels.

    Technical Specifications

    I am very sure you must have this kind of circuit diagram ready. While going through your blog I got lost and could not really choose one best fitting to my requirements.

    I am just trying to put my requirement here and make sure I understood it correctly.

    (This is a pilot project for me to venture into this field. You can count me to be a big zero in electrical knowledge. )

    My basic goal is to maximize use of Solar power and reduce my electrical bill to minimum. ( I stay at Thane. So, you can imagine electricity bills. ) So you can consider as if I am completely making a solar powered lighting system for my home.

    Whenever there is enough sunlight, I do not need any artificial light.2. Whenever intensity of sunlight drops below acceptable norms, I wish my lights will turn on automatically.

    I would like to switch them off during bedtime, though.3. My current lighting system (which I wish to illuminate) consists of two regular bright light Tube lights ( 36W/880 8000K ) and four 8W CFLs.

    Would like to replicate the whole setup with Solar-powered LED based lighting.

    As I said, I am a big zero in field of electricity. So, please help me with the expected setup cost also.

    The Design

    36 watts x 2 plus 8 watt gives a total of around 80 watts which is the total required consumption level here.

    Now since the lights are specified to work at mains voltage levels which is 220 V in India, an inverter becomes necessary for converting the solar panel voltage to the required specs for the lights to illuminate.

    Also since the inverter needs a battery to operate which can be assumed to be a 12 V battery, all the parameters essential for the set up may be calculated in the following manner:

    Total intended consumption is = 80 watts.

    The above power may be consumed from 6 am to 6 pm which becomes the maximum period one can estimate, and that’s approximately 12 hours.

    Multiplying 80 by 12 gives = 960 watt hour.

    It implies that the solar panel will need to produce this much watt hour for the desired period of 12 hours during the entire day.

    However since we don’t expect to receive optimum sunlight through the year, we can assume the average period of optimum daylight to be around 8 hours.

    Dividing 960 by 8 gives = 120 watts, meaning the required solar panel will need to be at least 120 watt rated.

    If the panel voltage is selected to be around 18 V, the current specs would be 120/18 = 6.66 amps or simply 7 amps.

    Now let’s calculate the battery size which may be employed for the inverter and which may be required to be charged with the above solar panel.

    Again since the total watt hour fr the entire day is calculated to be around 960 watts, dividing this with the battery voltage (which is assumed to be 12 V) we get 960/12 = 80, that’s around 80 or simply 100 AH, therefore the required battery needs to be rated at 12 V, 100 AH for getting an an optimal performance throughout the day (12 hours period).

    We’ll also need a solar charge controller for charging the battery, and since the battery would be charged for the period of around 8 hours, the charging rate will need to be around 8% of the rated AH, that amounts to 80 x 8% = 6.4 amps, therefore the charge controller will need to be specified to handle at least 7 amp comfortably for the required safe charging of the battery.

    That concludes the entire solar panel, battery, inverter calculations which could be successfully implemented for any similar kind of set up intended for an off the grid living purpose in rural areas or other remote area.

    For other V, I specs, the figures may be changed in the above explained calculation for achieving the appropriate results.

    In case the battery is felt unnecessary and the solar panel could also be directly used for operating inverter.

    A simple solar panel voltage regulator circuit may be witnessed in the following diagram, the given switch may be used for selecting a battery charging option or directly driving the inverter through the panel.

    In the above case, the regulator needs to produce around 7 to 10amps of current therefore an LM396 or LM196 must be used in the charger stage.

    The above solar panel regulator may be configured with the following simple inverter circuit which will be quite adequate for powering the requested lamps through the connected solar panel or the battery.

    Parts list for the above inverter circuit: R1, R2 = 100 ohm, 10 watt

    T1, T2 = TIP35 on heatsinks

    The last line in the request suggests an LED version to be designed for replacing and upgrading the existing CFL fluorescent lamps. The same may be implemented by simply eliminating the battery and the inverter and integrating the LEDs with the solar regulator output, as shown below:

    The negative of the adapter must be connected and made common with the negative of the solar panel

    Final Thoughts

    So friends these were 9 basic solar battery charger designs, which were hand picked from this website.

    You will find many more such enhanced solar based designs in the blog for further reading. And yes, if you have any additional idea you may definitely submit it to me, I’ll make sure to introduce it here for the reading pleasure of our viewers.

    Feedback from one of the Avid Readers

    I have come across your site and find your work very inspiring. I am currently working on a Science, Technology, Engineering and Math (STEM) program for year 4-5 students in Australia. The project focuses on increasing children’s curiosity about science and how it connects to real-world applications.

    The program also introduces empathy in the engineering design process where young learners are introduced to a real project (context) and engages with their fellow school peers to solve a worldly problem. For the next three years, our FOCUS is on introducing children to the science behind electricity and the real-world application of electrical engineering. An introduction to how engineers solve real-world problems for the greater good of society.

    I am currently working on online content for the program, which will FOCUS on young learners(Grade 4-6) learning the basics of electricity, in particular, renewable energy, i.e. solar in this instance. Through a self-directed learning program, children learn and explore about electricity and energy, as they are introduced to a real-world project, i.e. providing lighting to children sheltered in the refugee camps around the world. On completion of a five-week program, children are grouped in teams to construct solar lights, which are then sent to the disadvantaged children around the world.

    As a not 4 profit educational foundation we are seeking your assistance to layout a simple circuit diagram, which could be used for the construction of a 1 watt solar light as practical activity in class. We have also procured 800 solar light kits from a manufacturer, which the children will assemble, however, we need someone to simplify the circuit diagram of these light kits, which will be used for simple lessons on electricity, circuits, and calculation of power, volts, current and conversion of solar energy to electrical energy.

    I look forward to hearing from you and keep on with your inspiring work.

    Solving the Request

    I appreciate your interest and your sincerely efforts to enlighten the new generation regarding solar energy.I have attached the most simple yet efficient LED driver circuit which can be used for illuminating a 1 watt LED from a solar panel safely with minimum parts.Make sure to attach a heatsink on the LED, otherwise it may burn quickly due to overheating.The circuit is voltage controlled and current controlled for ensuring optimum safety to the LED.Let me know if you have any further doubts.

    Request from one of the avid readers of this blog:

    Hi, thank you for everything you do to help people out! My son would like to create a science fair experiment where he can show an electric car running on a solar panel only during the day while charging a battery and running on battery only during the night. For this, we planned to have a small solar panel connected to a battery and motor in parallel (see the attached drawing).

    • Will this work?
    • Can you recommend a size of solar panel, battery and motor?
    • As to not overcharge the battery, should a resistor be added? What size would you recommend?
    • Should a diode be added? What size would you recommend?
    • yes, it will work.
    • Use a 6 to 8V 1-amp solar panel.
    • The switch in series with the battery is not required. The remaining two switches are fine. This switch can be replaced with a 4 ohm 2 watt, or simply a 6 V flashlight bulb.
    • This bulb will illuminate while charging and will slowly shut off as the battery gets fully charged.
    • You can add a diode in series with the positive wire of the solar panel. It can be a 1N5402 diode
    • The battery can be any 3.7V 1200mAh Li-ion battery.
    • Motor can be any 3.7V DC motor.


    Couple more questions, I cannot find a solar panel with those specs, do you think you could send me one on the internet so I can find something similar? Great idea on the flashlight bulb, I assume this would need to be an incandescent light? Do you think this would properly protect the battery or would an additional resistor be needed?

    For the solar panel, you can search for a 6V 5 watt solar panel.Yes, the flashlight bulb will need to be an incandescent type, so that the filament can be used to control the current.The bulb should be enough to control the current, no additional resistor will be required.Please find the attached diagram for the detailed schematic.

    You’ll also like:

    • 1. nbsp3 Terminal Fixed Voltage Regulators – Working and Application Circuits
    • 2. nbspEasy Two Transistor Circuit Projects for School Students
    • 3. nbsp4 Universal Electronic Thermometer Circuits
    • 4. nbsp4 Simple Power Bank Circuits for Mobile Phones
    • 5. nbspTemperature Controlled Relay Switch Circuit
    • 6. nbspHigh Voltage, High Current DC Regulator Circuit

    Best Rechargeable Battery and Best Battery Charger

    My husband, August, did a ton of research to find the best rechargeable battery and the best battery charger for emergencies and every day use, so I asked him to help put together this post to share what he found out.

    We identify the best value and absolute best AA, AAA and 18650 rechargeable battery in this post. We also review a 28 watt solar panel that provides 5 volt USB power and emergency radios with built in solar and hand crank chargers to charge USB devices.

    Best Rechargeable Battery (AA, AAA and 18650)

    • Eneloop Pro AA 16 pack (most reliable)
    • Duracell Rechargeable AA 16 pack (workhorse – best life in most devices)
    • Tenergy Premium Pro 2800 mAh AA 20 pack (highest capacity – mAh)
    • Eneloop Pro AAA 12 pack (most reliable)
    • Duracell Rechargeable AAA 16 pack
    • Tenergy Premium Pro 1100 mAh AAA 24 pack

    Best Battery Charger

    • Best overall inexpensive charger is the XTAR VC4s Battery Charger charges AA, AAA, 18650 and other batteries using USB for power (does not charge protected 21700 batteries)

    Best Related Devices

    • Nekteck 28watt Solar Panel charge any USB device with the sun
    • Anker PowerCore 26800 portable battery pack portable external USB battery pack for cellphones
    • Kaito KA500L Voyager a Crank, Solar, Battery powered AM/FM, NOAA and 2 Band Shortwave Radio (receiver only) can charge a cellphone

    Best AA and AAA Rechargeable Battery

    A rechargeable battery will save you money. That rechargeable battery also reduces waste in the environment and provides options in emergencies. The best rechargeable battery brands vary over time, so we’ll update this post to keep up with the available tech. Right now it is a 3-way tie between Eneloop Pro, Tenergy and Duracell.

    Right now Tenergy is the leader for rechargeable AA or AAA batteries.

    We picked Tenergy Premium Pro because they are relatively inexpensive and generally well rated. They came in at the top 3 in all our tests and came in #1 for cost per mAh.

    Recommended AA and AAA rechargeable battery.

    Tenergy Premium Pro 2800 mAh AA 20 pack is an inexpensive bulk purchase high capacity option. The Tenergy Premium Pro 1100 mAh AAA 24 pack is our pick for AAA. They are the best for everyday use in items like clocks, toys, radios, remote controls and of course flashlights.

    The Tenergy AA and AAA batteries can up to 1000 recharge cycles. Pretty much all types of Tenergy rechargeable batteries are a good buy for everyday use and for use in a high drain device.

    The next best standard rechargeable battery brand for AA and AAA battery is the Eneloop 1.2v 2000 mAh AA 16 pack at and the Eneloop AAA 800mAh 1.2v 16 pack (check links for current prices). The best priced AA and AAA are the EBL AA and AAA, giving you the most bang for the buck, but note they have a shorter shelf life (faster self discharge).

    Absolute Best Rechargeable Battery

    The Panasonic Eneloop Pro AA 2550 mAh 8pack and Eneloop Pro 950 mAh AAA 8pack are the best for long term storage and intermittent high drain use. They are also the most expensive. We have been using these for years.

    The Eneloop Pro is “Low Self Discharge” which give them a long shelf life. They hold their charge so well that they hold 80% of the original charge even after sitting on the shelf for one year.

    The Eneloop Pro can also be recharged up to 500 times and have high mAh for high drain devices. All of these benefits make the Panasonic Eneloop Pro AA AAA batteries a very powerful popular choice for a rechargeable battery.

    AA and AAA Voltage

    Nearly all AA and AAA batteries are 1.2v not 1.5v. Some devices require 1.5 volts, such as trail cameras.

    If a device needs 1.5 volts we recommend either the Energizer Ultimate Lithium disposable or the 1.5 volt XTAR Li-ION 1.5v rechargeable batteries.

    The best 1.5v Li-ION AA rechargeable is the XTAR AA 3300mWh and XTAR AAA 1200mWh. There are some disadvantages. The XTAR batteries need a custom 1.5v charger, and are slightly larger than normal AA and AAA batteries- so will not fit in some devices.

    Also the 1.5v Li-ION are listed in mWh. The 3300mWh is 2750mAh (listed). Our actual testing put it at 1916mAh and 2874mWh. Lower than the advertised rate, but better than all the other 1.5v rechargeable batteries tested.

    Other AA or AAA Rechargeable Battery Options

    These are other batteries we considered (check links for current prices):

    • The Amazon High Capacity AA and Amazon High Cap AAA are decent. Even though the shelf life and mAh rating are a bit lower this is the best is overall “bulk buy”. Consider this if you use 100s of AA/AAA batteries.
    • The PowerEx AA was #4 in testing, but the price put it below the other options, and the PowerEx AAA was not readily available.

    The Best Rechargeable 18650 Battery

    Recommended 18650 Battery. We bought and recommend the Orbtronic 3.7v 3500 mAh 18650 protected mode battery. It has been a consistent performer in various flashlights around the house.

    It is hard to find right now so our recommended 18650 Rechargeable Battery is the LG MJ1 INR protected mode 18650. It is protected mode, its inexpensive and has a good mAh rating.

    The 18650 battery type is becoming more common as it is used as part of battery packs for everything from rechargeable toys, to laptops, to electric cars and of course flashlights. It is about 2x to 3x the size of a AA.

    Need more information on what an 18650 battery is? See this post: What is an 18650 Battery?

    Best Rechargeable C, D or 9 Volt Battery

    The EBL has good ratings and is our winner for these, but only by a hair. Be aware EBL overestimates the mAh ratings on nearly all their batteries. The good news is that testing came back with higher scores than many of their competitors, just not as high as EBL noted. Also there are not a lot of long term reviews of EBL.

    Note you might invest in eliminating devices that use C, D and 9 volt instead of investing in the C/D/9V rechargeable batteries and a C/D/9V charger. If you have the need here are our recommendations (check links for current prices):

    best, solar, battery, chargers, nimh
    • C Cell RechargeableEBL® 5000mAh Ni-MH C Batteries (6 pack)
    • D Cell RechargeableEBL® 10000mAh Ni-MH D Batteries (6 pack)
    • 9 Volt RechargeableEBL 600mAh 9 Volt Li-ion Battery(6 pack)
    • C/D/9v ChargerMrBattery Universal AA/AAA/9V/C/D Smart Battery charger

    Recommended Non-Rechargeable Battery

    Although we recommend you buy rechargeable batteries for most uses, it’s handy to have a stash of non-rechargeable batteries, too. We use non-rechargeable batteries for situations where the battery might be lost, or for very long life, low drain situations. In some rare cases devices need the 1.5 volts. Also non-rechargeable batteries will work better in extreme cold.

    You might want to use the lower cost batteries for use in gifts where you don’t want to give away your expensive rechargeable batteries. Nearly all standard AA and AAA batteries are 1.5 volts. Watch for sales and stock up so you don’t impulse buy at a convenience store because you need them and don’t have them. Also note, rechargeable and regular batteries tend to sell out quickly when emergencies hit – so buy them in bulk.

    You can find alkaline batteries fairly inexpensive in bulk. In packs of 100 to 500 you can get Energizer batteries between 35 to 40 cents and Duracell at 28 to 36 cents.

    Our favorite standard AA battery is the awesome lightweight 3000 mAh Energizer Lithium 1.5v AA (non rechargeable). The Energizer Lithium AA is lightweight and lasts 7 to 8 times longer than a normal AA battery BUT it costs more than a Tenergy High capacity 2600 mAh AA rechargeable battery.

    Compare Prices

    Compare before you buy standard alkaline or newer lithium non-rechargeable batteries. The regular Energizer AA (not the lithium) are under a dollar. At only one recharge, the Tenergy is cheaper (unless you lose the battery or give it away).

    As we noted, there are cases where the Energizer or Duracell make sense, but the rechargeable cost per use is decreasing rapidly. Even a more expensive rechargeable battery like Eneloop Pro AA breaks even at 9 recharges, and it can handle 500 recharges.

    Alkaline batteries are still cheaper per unit but the rechargeable battery price has been dropping to the point that the rechargeable battery will be a better straight cash value soon.

    If you only recharge them 3 times you have covered your total cost, and if you perform 4 or more recharges and you have saved money. Unless you need 1.5 volt batteries (which is rare) the Tenergy is the best bet.

    If you are going to buy alkaline batteries we recommend the AA and AAA Duracell PROCELL and Energizer Industrial. They are both good batteries for the price. The best are from online resellers in boxes of 10 or more.

    Overall Best USB Powered Charger

    The XTAR VC4s Battery Charger is our pick for overall best USB Smart charger and overall BEST CHARGER. It is simple. It uses USB for power, so a PC, USB A/C power supply or even a solar panel can charge one to four batteries. It supports the following battery types: 10440, 14500, 14650, 16340, 17335, 17500, 17670, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22650, 25500, 26650, 32650 and the rechargeable AA, AAA, C and D batteries. It does not support 9v rechargeable batteries.

    We tested it using power from standard USB ports, and even the Nekteck solar panel. It worked on all batteries tested.

    If you use the XTAR with a 2v USB it will charge much slower, the 5v USB is recommended. We have charged AA, AAA and 18650 batteries with it. It is not fancy but it works.

    Portable Solar Panel for Off Grid Battery Charging

    We recommend the Nekteck 28. The Nekteck 21 is a 21 watt solar panel that provides USB power. The Nekteck is a good emergency, camping or “Off Grid” battery charger. It is portable and can charge any 5 volt USB device such as: smartphone, tablet, and USB power packs.

    We bought one for outside events, camping and to be prepared for common emergencies like power outages, snow storms, hurricanes, floods and other disasters. The NekTeck successfully charged cellphones and batteries.

    We ended up selecting the Nekteck due to its high ratings, lower cost. It has lived up to those ratings. The NekTeck is simple, easy to use and it works.

    See our full Nekteck 21W Portable Solar Panel Charger Review (the 28 is a newer model)

    Portable Battery Pack for Charging Cellphones and Tablets

    The Anker PowerCore 26800 portable battery pack provides 5 volt USB power to a cellphone, tablet or any other USB powered device. It allows you to store up power from the Nekteck solar panel during the day and have it available in the dark or when it’s overcast.

    This battery pack acts as a portable charger to give you flexibility in providing power to your cellphone or tablet, when other power sources are unavailable.

    Emergency Radio with Built in Battery Charger

    We recommend that every emergency kit includes an emergency radio with AM, FM, and Weather. It can provide you critical info in an emergency. The radios recommended below can be powered by Hand Crank or Solar and can charge your smartphone or other USB device such as the battery pack (if you crank a LOT).

    Larger Solar/Crank Emergency Radio

    We recommend the Kaito KA500L Voyager radio because it can receive AM, FM, NOAA Emergency and Shortwave Radio 8” x 5” x 2.6” inches 19.5 oz. It can charge itself or charge a 5 volt USB device using the hand crank or solar panel.

    Small Crank/Solar Emergency Radio

    iRonsnow IS-088U Emergency Radio 5 x 1.6 x 2.4 inches 7.2oz – this one is lightweight and compact for a backpack, small get home bag or if you are a prepper a bug out bag. It can charge itself or a 2.7 to 4 volt USB device using the crank or solar panel.

    Battery “Converters”

    In an emergency you might only have AA batteries. The Sanyo Eneloop Spacer Pack: 4 Pack of C-size and 4 Pack of D-size Adapters are a way to use AA rechargeable batteries for devices that require C or D batteries. The wattage will be lower, but it will work.

    The adapters slip over your AA batteries so they can be used in place of C and D cells. They don’t change the power characteristics of the batteries, but if you need to make the proverbial square peg fit in a round hole, they work and make the AA batteries fill multiple roles. We have successfully used these.

    Battery and Battery Charger Storage

    When my husband and I were first married, there were many times when I went looking in the kitchen “stuff” drawer for the right battery, only to find out that we didn’t have the right size battery or the rechargeable batteries were completely dead. Since then, we’ve gotten more organized.

    For Christmas a few years ago, my husband’s parents gave us a heavy duty storage case stocked with long life alkaline batteries. (Shown below.) (If you’re reading this, thank you grandma and grandpa! We use it regularly.)

    We have three spots we keep our batteries and chargers. (Yes, the collection has grown over the years.)

    The heavy duty storage case that my in-laws bought is the Flambeau 7320 Double Satchel Tackle Box (pictured above and below), which is impact resistant and has 27 individual storage compartments. Both sides open up to make it easy to see everything that’s in it. This is a GREAT box and has held up for years and keeps the batteries organized well.

    We also bought a plain, sturdy toolbox to hold everything that doesn’t fit in tackle box or organizer. We use it for the bulkier chargers and oddball battery related items.

    Drawer Battery Organizers

    There is a smaller battery rack with built in tester that now lives in the kitchen stuff drawer to keep batteries organized. If we get a new one it will be more like the Range Kleen Battery Organizer Case or the The Battery Organizer Storage Case is a another option. It also includes a battery tester.

    Why buy a Battery Charger and Rechargeable AA or AAA Batteries?

    It’s easy to take things for granted. We assume electricity and lighting are always available, even though we know they are not. My mom used oil lamps for lighting as a kid, now we flip a switch and the light comes on. (Almost all the time.)

    Our electric grid is aging, and bad weather or unexpected power outages can happen at any time. It just makes sense to plan ahead to make sure we have the power we need when we need it.

    Using common sense we can increase our safety, reduce the amount we pay for batteries and lower our environmental impact. Remember, both a rechargeable and non-rechargeable battery can and should be recycled. See “Battery Recycling – How to Recycle Different Battery Types and Corroded Batteries Safely” for more information.

    I hope you find this post useful. It was a family effort, with bits contributed from my husband, my son (August V) and myself, and it took a while to pull everything together, plus my poor country internet connection kept dropping while I was working on it.

    s you may also find useful:

    Originally published in 2015, updated in Sept 2021.

    It makes a HUGE difference when you share our articles. Thank you so much!

    The 8 best solar battery chargers for your car, phone, boat, RV, and more!

    Many of the devices that we depend on throughout the day run on batteries and it’s never fun when those batteries run down. A solar battery charger is an easy, earth-friendly way to keep all your batteries juiced up and ready to go. The beauty of a solar battery charger is that they work anywhere where you can find sunshine, no outlets required! In most cases, all you have to do is put the solar panel in the sun and connect your battery. It’s that easy.

    A solar battery charger will include a solar panel, as well as wires to connect the solar panel to your battery or device. Some kits also include a few tech items like charge controllers and blocking diodes (more on those later).

    Before we move on, here’s something important that you should know. Most 12-volt solar chargers are designed to maintain your battery’s charge when it’s not in use. These small solar chargers aren’t big enough to fully charge dead batteries, they trickle charge them instead. This ensures that the battery is always ready for your next adventure.

    Solar chargers for smartphones and tablets, however, produce the 5-volts your iPhone needs to recharge after a complete discharge.

    Needless to say, solar chargers for vehicles and smartphones are different and not typically interchangeable. We chose a variety of chargers so that you can get a good idea of what’s available.

    We searched through hundreds of options and narrowed our list to eight products in eight different categories. All the solar chargers we’ve included are cost-competitive, durable, and backed up with great customer service.

    Of course, some are more expensive than others, but if they are, we’ve laid out exactly why you’d want to spend that extra cash. After taking a look at these sweet products, we think you’ll agree!

    Solar Battery Charger Reviews

    Read on to learn more about each of the best solar charger companies on our list to find the perfect one for your battery or devices.

    Best Solar Battery Charger for Cars

    Quick Look: A physically large, waterproof solar charger that comes in three sizes, from 5W to 15W, built-in controller, and diode.

    If you’re looking for a well-built, leave-it-and-forget it solar battery maintainer for your car, Battery Tender’s Solar Charger is the perfect solution. It is heavy-duty, waterproof, and comes with everything you need to keep your battery topped up with free, clean energy.

    Battery Tender has been around for ages and you can find their products online and in stores like Walmart and auto parts stores. On Amazon, you can find their Solar Charger in 5W, 10W, and 15W. Each comes with alligator clips to easily attach to your battery.

    It’s waterproof, so you can leave it outside, but remember it’s quite large – the 15W panel is over 3 feet long and a foot wide. However, it’s got some great features that set it apart from almost every other solar battery maintainer out there.

    First, Battery Tender’s Solar Charger includes a built-in charge controller to protect your battery from inconsistent charging and over-charging.

    Many solar chargers don’t include a controller, so this is a nice addition. Some manufacturers and users argue that including a charge controller on solar panels this small is overkill, but they are a vital addition if you plan on using the charge controller consistently.

    Second, Battery Tender also includes an integrated blocking diode in their solar chargers. Without a blocking diode, your battery can leach electricity when the solar panel isn’t in use, leading to a dead battery. If you don’t have a blocking diode in your solar charger, you have to disconnect your battery from your solar charger every night.

    People use these solar chargers for all sorts of vehicles: boats, RVs, cars and trucks, and camper trailers. Some even permanently mount the solar charger to the front or top of their camper trailer.

    Customers confirm the charger’s great performance stats and noted that, even though the chargers are large, they are lightweight and easy to maneuver.

    If you’re looking to keep your car topped up, you can simply attach the alligator clips to your battery and place the solar panel on your dash and let the sunlight do its work.

    Bottom Line: Battery Tender’s Solar Charger is a bit more expensive than others on our list, but you get an integrated charge controller and blocking diode. Even though it’s larger than others on our list, with these nice additions you don’t have to worry about your car’s battery. It’s one of the safest, easiest chargers to use.

    Best Solar Battery Charger for Boats

    Quick Look: DuraVolt’s sturdy solar chargers are specifically designed for heavy-duty marine use.

    The DuraVolt 20W Marine Solar Battery Charger tops our list for the best solar battery charger for boats.

    Solar panel manufacturer ITC Solar originally manufactured their DuraVolt solar panels to power high-tech buoys designed to monitor water quality in Tasman Bay in New Zealand. Realizing recreational boaters and other industries could benefit from these small, durable solar panels, they branded them as DuraVolt and now you can find them on Amazon.

    These solar chargers are semi-flexible and covered in a plastic film and aluminum backing. The solar charger is wrapped in a heavy-duty rubber gasket with a mounting hole in each corner. Their 20W solar charger is quite small, only 14” x 16” and just 1/4” thick.

    The solar chargers come pre-installed with an SAE output plug, as well as alligator clips, battery terminals, and a lighter adapter so you can charge your boat in whatever manner is easiest.

    An important note: The charger doesn’t come with a blocking diode or charge controller.

    DuraVolt claims that a blocking diode is unnecessary, thanks to their solar panels’ high-quality internal components. If you’re not comfortable taking their word for it, they will send you one for free.

    A handful of buyers have installed blocking diodes or kill switches themselves to avoid any potential issues.

    DuraVolt also notes that their 12v chargers don’t need a charge controller, as they use self-regulating panels with a lower operating voltage than other 12v solar panels. A handful of buyers still use a charge controller, but the manufacturer notes that it is not necessary thanks to this low voltage.

    Many buyers permanently attach the charger to the deck or T-top and use it to keep the battery topped up when moored or when out on the boat during the day.

    Reviewers continually praise the charger’s simplicity and toughness. All you have to do is bolt it down, put on the right adapter, and connect it to your battery.

    Bottom Line: The DuraVolt 20W Marine Solar Battery Charger is the perfect option for your boat or any other intense setting where ruggedness and dependability are key – and water is imminent.

    Best Solar Battery Charger for RVs

    Quick Look: Thanks to the ultra-strong magnetic back, DuraVolt’s Magnetic Battery Maintainer is about the easiest solar charger to install.

    We looked at DuraVolt’s Marine Solar Charger above, but their solar chargers are not just for boats. DuraVolt also manufactures a magnetic solar charger based around the same extremely rugged solar panel as their marine products.

    Their Magnetic Battery Maintainer is specifically designed for fifth wheel and camper trailers. The 8.3W solar panel has an extremely powerful magnetic back that sticks to any surface, including your fifth wheel’s hitch or even the hood of your vehicle.

    DuraVolt uses neodymium magnets, the strongest magnet on the market, for these chargers. Many users note that they were initially skeptical of the magnet, but they found that the panel does not move an inch even after high speeds and bumpy roads. This makes DuraVolt’s magnetic solar panel – quite literally – the easiest installation of all the chargers on our list!

    Just like DuraVolt’s marine charger above, this solar panel is covered in a semi-flexible plastic film and aluminum backing for maximum durability, while also making the solar panel incredibly light. It’s 12” x 10”, just a ¼” thick, and weighs 1.9 pounds. As the solar panel is semi-flexible, it can flex to the curve of your vehicle’s hood or any other metal, ‘gently curved’ surface.

    The charger includes a 10′ cord that ends with an SAE output as well as alligator clips and battery terminal adapters.

    DuraVolt claims that their solar battery chargers do not need a blocking diode or charge controller, thanks to their unique design and quality components. Some buyers choose to add them after buying the kit, but most seem to install the kit exactly how it is and the charger still works great.

    DuraVolt customers typically have two things to say about the company. First, their solar panels are incredibly durable. You’ll certainly pay more for them, but you’ll also know your RV’s battery will always be ready to go. Second, DuraVolt’s customer service is excellent. Wait time is short, there’s no long phone prompt menu, and the employees are knowledgeable.

    Bottom Line: DuraVolt’s Magnetic Battery Maintainer might be more expensive than other similarly-sized battery chargers, but it’s easy to install, extremely rugged, and backed up by excellent customer service.

    Best Solar Battery Charger for Motorcycles

    Quick Look: A compact, low-cost solar charger with great customer reviews.

    Keeping your motorcycle battery topped up in the off-season is easy with POWOXI’s 3.3 watt solar charger. It is compact and 100% waterproof.

    The charger uses amorphous silicon solar cells, which perform well in low-light conditions. At 3.3W, you should have more than enough power to keep your bike’s battery charged up. The solar panel is encased within UV-resistant ABS plastic and includes mounting holes in each corner, along with suction cups to mount the panel.

    The charger itself is 14” x 8.5” and just under an inch thick. At only 2.2lb, this compact solar panel is extremely portable and easy to set up. It includes a 10’ cord ending in an SAE output, with alligator clips and a cigarette lighter adapter (if you want to charge a vehicle).

    POWOXI also integrates a blocking diode into the charger, so you’re able to leave the charger connected to the battery 24/7 without fear of damaging it (read more on blocking diodes at the end of this article).

    The solar panel also includes a small blue LED light right on the front which flashes when it is charging your battery – a nice little touch that allows you quickly keep tabs on your battery’s charging status.

    This kit doesn’t come with a charge controller, but most experts agree that any 12v solar kit under 5W doesn’t need a controller, so you should be good to go without one.

    Of course, this solar charger isn’t just for motorcycles. Customers report using this little battery charger for jet skis, RVs, trucks, and cars. Many users report that it works great in low light, cold weather, and extreme heat – exactly what you want to hear for an all-weather, outdoor solar charger.

    If you want to shave some costs, you’ve got a couple of options. First, POWOXI also manufactures a monocrystalline version of this same solar charger for a bit less. It won’t produce as much electricity in low light conditions, but if you’re just going to connect the charger and leave it for a full season, it’ll work just fine and save you a few bucks.

    If 3.3W is still too big for your needs, POWOXI also manufactures a smaller 1.8W version at about half the price, so take a look at that one for an even more budget-friendly option.

    Bottom Line: POWOXI’s solar battery charger is low-cost, compact, and easy to set up, perfect for winter when your motorcycle is in storage.

    Best Solar Battery Charger for Phones

    Quick Look: This compact, durable solar battery charger includes 2 USB ports for your smartphone and includes a built-in ammeter that tells you how much juice your solar panels are producing.

    BigBlue’s 5v, 28W solar charger packs a punch big enough to charge your smartphone, tablet, or any other 5v gadget. It uses Sunpower solar panels, some of the most efficient solar panels currently available! Needless to say, it’s a quality item that you can depend on.

    The charger comes with two USB ports, providing up to 2.4 amps per port, with a max of 4 amps overall. This charger detects your connected devices and charges each in the fastest method.

    Some solar chargers have a hard time restarting after shade or rain block sunlight. With these products, users have to unplug their devices to jolt the device into working again. BigBlue has solved the issue by including a chip that automatically pauses charging when shaded, then restarts when sunlight is available again. Needless to say, this means you don’t have to worry about your charger no matter the weather.

    The device even includes a built-in ammeter, so you know how much electricity your solar panels are producing. This is the only charger on our list that has this very helpful feature!

    The solar charger measures 11” x 16” x 1” when closed, and weighs just 21 ounces. It’s smaller and lighter than a laptop, so it’s easy to throw in a backpack when you’re on a day hike or moving around the city all day. Once unfolded, you’ll find four small solar panels wrapped in heavy-duty, waterproof canvas.

    This is one of the more popular solar chargers for iPhones and other smartphones and for good reason. Users routinely say the charger is durable, fast-charging, and well-priced.

    Some seemed disappointed that the charger doesn’t provide a full 28W, but unless you’re in absolutely perfect conditions, no solar panel is going to provide its nameplate wattage – that’s just how it works.

    Bottom Line: BigBlue’s solar charger is the perfect option to charge your iPhone. It’s extremely portable, low cost, and well-made.

    Best Solar Battery Charger for Laptops

    Quick Look: A serious off-grid solarbattery kit that provides 5 to 24 volts and can charge laptops, phones, tablets, and other gadgets.

    The most expensive item on this list, but also one of the most capable, Voltaic System’s Arc 20 is specifically designed to charge laptops and includes not only a solar panel, but a battery pack as well. It’s designed and built for those times when the utility grid is simply not an option.

    Most of the solar battery chargers that are designed for smartphones typically provide only 5v of power because that’s all the power you should need to charge your phone or tablet. The Arc 20 includes three different power output options:

    • 1 USB 5v/2A output
    • 1 USB-C 5v/3A output
    • 1 high-voltage laptop port (12V/6A, 16v/5A, 19v/4.5A, and 24v/3.5A)

    The battery pack has a capacity of 24,000mAh, enough for 1 laptop charge, 7 smartphone charges, or 3 tablet charges. The kit pretty much has everything you need to get all your devices running off solar, including:

    • DC output for laptops
    • 10 connectors for different laptops, but check the list to make sure your laptop is one of them!
    • Car charger
    • AC wall adapter

    With pass-through charging, you can also charge both the battery pack and your device from the solar panel at the same time. Voltaic Systems estimates 6 hours for a full laptop charge and 1 hour for smartphones.

    The foldable 20W solar panel is wrapped in heavy-duty canvas and outputs 18v to charge the battery pack in just six hours – pretty quick considering the size of the battery pack.

    The whole kit weighs just 3.25lb and is about the same size as a laptop, so you can add it to your backpack without too much trouble.Customers absolutely love this kit. This kit doesn’t have as many reviews as some, probably due to the higher cost, but customers certainly put this thing through the wringer, claiming it’s for serious off-grid use and that it’s up to the task.

    Peace Corps trips in West Africa and extended trips in the backcountry are just a couple of the situations in which people have successfully used this charger.

    Bottom Line: The Voltaic Solar Charger may be pricier than others on our list, but it is built to take any extended, harsh off-grid trip you can throw at it. Buy it and know you’ll always have juice for your laptop, no matter what.

    Best Solar Battery Charger for Backpacking

    Quick Look: A thin, ultralight – and ultra simple – solar battery charger perfect for those extended backpacking trips.

    When backpacking, you’re carrying everything right on your back for days at a time. Shaving weight from your pack means you can travel faster, longer, and with less fear of tiring out or injury.

    With smartphones increasingly used as camera, compass, GPS, map, guidebook, notebook, and emergency communicator, keeping your phone charged becomes increasingly important.

    Of course, a solar charger is just one more thing to bring, but thankfully Renogy’s E.FLEX solar charger is perfectly designed for backpacking trips. First off, it’s only 0.08” thick and 9” x 6” when folded, so it’s easy to throw it in your pack or clip to the outside of your backpack while hiking.

    Second, it’s incredibly lightweight at just 0.7lb – one of the lightest solar chargers, if not the lightest, on the market.

    It comes with 4 suction cups and 2 small carabiners so you can attach it to the car windshield on the way to the trailhead or to your backpack or tent while in the backcountry.

    best, solar, battery, chargers, nimh

    At 10W, this solar charger doesn’t produce too much energy, but it is certainly enough for your smartphone. Users note it can charge smartphones and laptops in a few hours, but it needs full sunlight to charge efficiently. If you’re stuck in cloudy or rainy weather, 10W just isn’t enough to charge.

    However, don’t let that turn you off to this awesome little solar charger. Renogy makes excellent solar-related products and their gear always enjoys top-notch reviews from customers. This small solar charger is no different. Most customers praise its charging abilities, simplicity, and lightweight design.

    Renogy actually makes a few different models of the E.FLEX solar charger:

    • 10W Plus: This is the product we review here. It features a polycrystalline silicon solar panel and it’s thinner and lighter than the standard option below.
    • 10W Mono: About half the price of the 10W Plus, the 10W Mono is about 2 ounces heavier and almost 2x as thick (which, at 0.13 inches is still incredibly thin). Other than that, it’s got the same specs as the Plus (namely 5v/2A power output) at a much lower price.
    • 5W Plus: All of the benefits of the 10W Plus, but half the wattage and only 5.6 ounces.
    • 5W Mono: Same as the 10W Mono, but only 5 watts and 6.7 ounces.

    Bottom Line: Renogy’s E.FLEX line of ultra-thin solar chargers are the best option available for backpackers. They’re cheap, reliable, and extremely lightweight.

    Best Solar Battery Charger for Rechargeable Batteries

    Quick Look: Solar battery charger for AA, AAA, and 9v batteries. Includes 7 charging bays, 2W crystalline solar panel, and built-in LED indicator lights. Compact box design with retractable handle.

    Keeping all of our devices well charged is important, but sometimes we need batteries for other things like flashlights, toys, and remotes controls. Wouldn’t it be great if you could charge those batteries with solar as well? Well, great news, you can!

    With this portable battery charger from Sunway Solar, you can charge your AA, AAA, and 9v batteries anywhere where you can find sunshine.

    This small box-like charger is 6.9″ x 6.7″ and weighs only 1.15lbs, the perfect size for camping trips. The retractable handle makes it extra portable and easy to set up. The handle doubles as a stand so you can angle the solar panel for effective charging.

    Sunway Solar also included convenient LED indicator lights so you always know your charger’s charging status. It also comes with a built-in diode to prevent power leaching.

    Bottom Line: The Sunway Solar battery charger is the perfect way to keep all your household battery-operated devices charged up. The compact design makes it easy to use at home or on the go!

    Tips for Choosing the Right Solar Charger

    Solar battery chargers are pretty simple pieces of equipment. That being said, there are a few things you need to know if you’re in the market for a new solar charger. Here are a couple of tips to help you find the right solar charger for you.


    With solar chargers coming in sizes from 2W to 30W, finding the right size for your needs is key. You want it to be big enough to keep your battery topped up but not too big, since you don’t want to waste money.

    Most solar chargers for vehicle batteries come in around 5W to 15W. Larger vehicles typically require larger batteries, but it depends on your vehicle’s phantom load (the power pulled from the battery even when the key isn’t in the ignition) and driving frequency. If you’re worried, 10W to 15W should be enough to keep any vehicle ready for use.

    If you’re looking to charge your smartphone or tablet, you’ll probably want a larger solar panel. Most solar chargers for small devices sit around 15W to 30W, with the average coming in around 22W to 28W. Exactly how many watts you need depends on the specific devices you want to charge, as well as how many devices. We recommend 20 watts or more for general use.


    If you’re looking for a solar charger for your 12v battery (like the one in your car, boat, or RV), you’ll want your charger to include a blocking diode and the correct cords for your application. You’ll want alligator clips for short-term use, battery terminal rings for long-term storage, cigarette adapters if you want to charge in the car.

    On top of that, you’ll want to ensure the panel can be installed in the manner you’d like. Does it have mounting holes in each corner? Can it be glued down or not? These questions are easily answered by reading the description and customer reviews or even asking the extremely-helpful Amazon community.

    If you want to charge your 5v gadgets (smartphones and tablets), you’ll need to ensure the charger has enough ports for your needs as well as the right type – USB, USB-C, etc.

    Also, how about mounting? Does it have holes in each corner? Does it come with carabiners or suction cups to clip or stick to different surfaces? Take a second to read the description and reviews to see exactly what features come with the charger.


    Solar battery chargers aren’t particularly expensive, typically between 20 to 60, depending on the size of the solar panel and the included features. The higher-end models can come in at 100 and tacking on a battery pack can add even more.

    If you’re looking at solar chargers for your vehicle or boat, you’ll find that solar chargers are a bit more expensive than a typical battery charger that you plug into your wall. However, the benefits of a solar charger, mainly its portability and versatility, far outweigh the slight cost increase.

    Charge Controllers and Diodes

    If you’re looking at solar chargers for a 12v battery, you’ll probably see a lot of discussion around blocking diodes and charge controllers and whether this or that particular product needs one. But what the heck are they? And are they even important?

    Blocking Diodes – You Need Em!

    Most of the better solar chargers include a blocking diode integrated into the solar panel. The diode allows electricity to flow towards the battery, but blocks electricity from flowing in the opposite direction. Without a blocking diode, your battery can send electricity back to the solar panel at night, when the panel isn’t producing electricity.If your solar charger doesn’t have a blocking diode, you’ll need to disconnect the charger from your battery each night. With a blocking diode, you don’t have to worry about this power leaching.

    Unless the manufacturer specifically notes that blocking diodes aren’t necessary (like DuraVolt above), make sure your solar battery charger includes one!

    Charge Controller – You Might Need It

    Charge controllers keep your solar panel from overcharging and damaging your battery. For large solar installations, they are a required piece of equipment. Small battery chargers don’t typically include a solar charger and many manufactures note that 12v solar chargers don’t need a controller, as they don’t provide enough juice to overcharge the battery.

    However, some recommend purchasing and using a charge controller for any solar panel larger than 5W. Many people report they use their solar battery charger without any charge controller and haven’t experienced any negative issues.

    If there are ever any voltage spikes or your battery charger is left connected to your battery for an extended period of time, there’s a chance you could damage it.

    If you’re worried at all, it’s probably best to either buy a solar charger with an integrated charge controller (like the Battery Tender above) or spend the extra 20 on a separate charge controller.

    Pros and Cons of Solar Chargers

    Solar chargers are a great way to keep your batteries easily charged up, but they’re not perfect. Let’s take a look at the pros and cons of solar chargers.

    Pros of Solar Chargers

    • Free energy: This is an easy one. Once you buy the solar charger, you never have to pay for electricity or generator gas to top your batteries up. Use it for a year or 20 years, your fuel costs will be the same: absolutely zero.
    • Charge without utility power: This is the biggest draw to solar chargers. Since they’re powered by the sun, you’re able to charge your devices anywhere there’s sunlight. On your boat, while camping, in your RV, your driveway – you name it! No longer do you have to worry about moving your batteries into the garage or running cords outside. Just hook the charger to your battery and put the solar panel in the sun!
    • Easy setup: No need to take out your batteries or move your boat or ATV close to the garage. Just hook your battery or smartphone up to your solar charger and place the charger in the sun. Done!

    Cons of Solar Chargers

    • Not a ton of power: Solar chargers typically only produce about 2W to 30W of electricity, depending on the intended use. It’s more than enough to keep your battery topped up, but that’s not a lot of electricity. You’ll need to base the size of your charger on your own needs. The more you use the battery, the bigger your solar charger needs to be. If you want to keep two batteries fully charged, you’ll need to buy two solar chargers.
    • Higher cost: Solar battery chargers are more expensive to purchase than plug-in chargers. That’s just a fact. Of course, with a solar charger, you don’t have to pay for any electricity, but we add this to the list of cons to keep everything balanced.

    Overall, we think the flexibility, functionality, and ease of use of solar-powered battery chargers easily make up for their higher purchase price.

    If you’re looking to keep your vehicles’ battery or smartphone topped up, solar chargers can get it done.

    How To Get The Most Out of Your Solar Charger

    These chargers are easy to use and require little to no maintenance, but there are a few things you can do to ensure that you get the most out of your charger.

    Keep it clean

    If you know anything about solar panels, then you should know that keeping the panel clear of dirt and debris is vital. It cannot generate power if the sun can’t get through, so make sure your solar panel is clean.

    Watch the weather

    It is important to know what your solar charger is capable of in terms of surviving the weather. Many models are weatherproof, but some are not, so be sure to double-check your panel’s specs before leaving your panel out in the bad weather.


    We hope you enjoyed our list of the best solar battery chargers in 2021. Just as a quick review, we looked at hundreds of battery chargers on the market, and chose the best in 8 different categories. Here are the top picks.

    Compare the Best Solar Battery Chargers for 2021

    • Best Solar Battery Charger for Cars: Battery Tender Solar Charger
    • Best Solar Battery Charger for Boats: DuraVolt 20W Marine Solar Battery Charger
    • Best Solar Battery Charger for RVs: DuraVolt Magnetic Battery Maintainer
    • Best Solar Battery Charger for Motorcycles: POWOXI Solar Battery Charger
    • Best Solar Battery Charger for Phones: BigBlue 28W Solar Charger
    • Best Solar Battery Charger for Laptops: Voltaic Systems Arc 20 Rapid Solar Laptop Charger
    • Best Solar Battery Charger for Backpacking: Renogy E.FLEX 10W Ultra Thin Solar Charger
    • Best Solar Battery Charger for Rechargeable Batteries: Sunway Solar Store Solar Battery Charger

    Take a look at the products above and find the best solar battery charger for you! Like we’ve pointed out, the best options are durable, cost-competitive, and backed up by excellent customer service. And beyond the versatility and ease of use, using a solar battery charger and running your life off the sun –even if it’s just a tiny part of it – is great for you and the environment!

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