How to Charge Lithium-ion Battery with Solar Panel
Lithium-ion batteries are a great piece of equipment for your solar system since they can be recharged and keep your lights on well after the sun has set. You can use these in many portable electronics.
Lithium batteries can be charged by these solar panels when they lose their charge.
It’s important to know how to charge lithium-ion batteries with a solar panel. It can be quite a tricky process which is why you may need to do some research before doing so.
In this article, we discuss what lithium-ion batteries are and how to charge them safely. We also cover everything that lithium-ion batteries can be used for, and what you need to charge them.
What Are Lithium Ion Batteries?
A lithium-ion battery is a type of rechargeable battery. It’s charged and discharged by lithium ions that move between the negative and positive electrodes.
Batteries that can be recharged repeatedly are called secondary batteries. Disposable batteries are called primary batteries.
Lithium-ion batteries are suitable for storing high-capacity power. This is why they are used in various applications. These applications include electronics like smartphones and computers, production equipment, cars, and industrial robots.
Different Types of Lithium Ion Batteries
Lithium-ion batteries are available in many different shapes for various applications. These shapes include:
The rigid plastic case (large threaded terminals)
Small cylindrical (single cell with, a solid body, with no terminals)
Flat or pouch (soft, flat body)
Large cylindrical (single cell, solid body, with threaded terminals)
Other characteristics of Lithium Ion batteries are their Current Capacity and Nominal voltage.
Nominal voltage is the normal voltage that the battery operates at. Some batteries may have a higher voltage when fully charged.
To further increase the current capacity, you can connect batteries in parallel. However, this process is slightly more complicated than wiring in series. This is because you need to match the internal impedance of each battery.
Can I Charge a Lithium-ion Battery with a Solar Panel?
You can charge a lithium battery with a solar panel. However, the solar panel must have the correct output power requirements to charge the battery.
The first important factor to keep in mind is potentially overcharging your battery. Lithium-ion batteries damage easily when they are charged beyond their nominal voltage.
Lithium battery chargers don’t have trickle charging. Instead, the charger stops charging the battery when it has reached its desired voltage to keep the lifespan longer.
It’s not ideal to connect a solar panel directly to a lithium battery. This is because the solar panel has no way of detecting when to stop giving power to the battery.
It continuously releases energy into the battery whenever it produces electricity from sunlight which results in overcharging and damage to the battery.
If you connect a solar panel directly to a load, issues could potentially occur. These include:
- The solar panel being overloaded
- The lithium battery not being able to receive maximum power from the solar panel
- Charging the lithium battery is reliant on the weather. Cloudy conditions will not be ideal.
What Type of Solar Panel can Charge a Lithium-ion Battery?
As long as you use a charge controller then any type of solar panel will charge a lithium-ion battery.
The type of solar panels they can be used with are:
- Flexible solar panels
- Rigid solar panels
- Portable solar panels (briefcase/suitcase)
- Bifacial solar panels
The wattage of the solar panel doesn’t matter. However, if the solar panel wattage is high then it will charge the lithium-ion battery quickly. The higher the wattage of a solar panel array the faster it will charge a lithium-ion battery bank.
You’ll need to invest in a high-quality charge controller if you want to charge multiple batteries with a single solar panel.
What Do I Need to Charge a Lithium-ion Battery with a Solar Panel?
Solar panels aren’t normally used by themselves to charge a battery. A few components are used in something called a Solar Power System.
The solar power system is used to power electrical and electronic loads.
Components of a solar power system include:
- Rechargeable battery
- Solar Panels
- Charge Controller
- Inverter (AC applications)
If you already have a solar panel and a rechargeable battery then all that you need is a charge controller.
The charge controller prevents the battery from overcharging. It also constantly charges the battery and protects the solar panel from any reverse current.
Since there are many different types of batteries for solar systems, there are many different types of charge controllers. Each controller is designed to meet the individual needs of each battery type.
You need to buy a solar charge controller that’s specifically designed for lithium batteries. This ensures that the battery stops charging when the nominal voltage is reached.
Charging a Lithium-ion Battery
Lithium-ion batteries are unique in their charging requirements compared to batteries with different chemistries. There are strict requirements when it comes to charging these batteries.
The battery charger is a voltage-limiting device. It has differences from other chargers.
The main differences include:
- It can tolerate tighter voltages
- Higher voltage per cell
- Trickle charging is when a battery charger is capable of charging a fully charged battery. It’s done at a rate equal to its self-discharge rate. This allows the battery to keep its fully charged level.
- Absence of trickle or float charging
The charger comes with certain features to prevent overcharging. These include features such as an end-of-charge detection circuit to keep track of when the battery is fully charged.
Steps to Charge a Lithium-ion Battery
When charging a lithium-ion battery, you need to ramp up the voltage and current followed by a flat voltage and lower amperage.
Step 1: Get the right materials
- A Solar cell 6V
- 1 x Li-Ion charger board TP4056 (choose a board with 4 outputs. 2 for battery, 2 for connecting the device)
- 1 x Schottky diode
- 1 x Lithium. Ion battery
- 1 x Lithium. Ion battery holder
- 1 x cables
- 1 x solder tools (station, tin, rosin, etc.)
Step 2: Get the Correct Solar Cell
The current from the solar cell can be variable. You can choose a 500 mAh solar cell or a 1 Ah solar cell.
For the Lithium Ion battery, you can choose a solar cell with 5V and 160 mA. Shop Solar Kits has a range of 200-watt flexible solar panels at affordable prices.
Step 3: The Circuit
There are positive and negative terminals on solar panels. Connect the positive terminal of the solar cell to the anode of the diode. Connect the negative terminal of the diode to the positive input.
Also, connect the negative terminal of the solar cell to the negative input. Lastly, connect the battery and the positive terminal of the battery to a similar negative terminal.
What Can a Lithium-ion Battery be Used for?
You can use lithium-ion batteries for many things. They can be used for anything from small kitchen appliances to large commercial trucks. They’re excellent if you plan on connecting your solar system off-grid.
You also need batteries for solar panels.
The main things that you would use these batteries for are:
- A boat
- A recreational vehicle
- A motorhome
- A camper van
- A caravan
- A trailer
- A yacht
- A holiday cabin
- A shed or a garage
You will need to know how to install solar panels too. For example, installing solar panels on a van.
Do You Need a Solar Charge Controller for a Lithium-ion Battery?
You need a solar charge controller to charge any 12V battery with a solar panel. You also need to take into account the correct size cable for the 12v solar panel.
A portable generator may be an exception because it should have one built-in and an inverter.
You may not know how to set up solar panels off the grid. Off-grid residential installations also would need a solar charge controller.
Your battery is at risk if you charge it without a controller. This will cost you a lot of money. You can potentially damage the cells and destroy the battery.
Lithium-ion batteries have a battery management system (BMS) to prevent overcharging. You should, however, always have a solar charge controller in your solar setup kit.
Your lithium-ion battery will be kept safe if you invest in a good quality solar controller. This will make the charging process more efficient.
A lithium-ion battery is a rechargeable battery. We now know that these types of batteries come in many different shapes to be used for a variety of different applications.
You can charge a lithium battery with a solar panel but knowing how to do it can be tricky. The solar panel must have the correct output power requirements for the battery to charge.
If you use a charge controller, then any type of solar panel can charge a lithium-ion battery.
You will need certain components to charge a battery with a solar panel. These include a charge controller, solar panels, and a rechargeable battery.
By following the tips and steps in this article, you should have knowledge of how to charge a lithium-ion battery with a solar panel.
Make sure you purchase the right materials and tools. If you have a good solar kit, then charging your lithium-ion battery will be an easy task.
Did You Find Our Blog Helpful? Then Consider Checking:
- Sailboat Solar Panel Installation
- Mixing Different Wattage Solar Panels
- Two Charge Controllers One Solar Panel
- Solar Panel Charge Controller Troubleshooting
- How Many Solar Panels to Charge an Electric Car?
- How to Connect Solar Panels to Battery Bank Charge Controller Inverter
- What Size Solar Panel to Charge 12v Battery
- How to Calculate Solar Panel Battery and Inverter
- How Many Batteries Per Solar Panel?
- Solar Panels Wattage Calculated
- How Many Solar Panels Per Acre?
- Solar Panel Watts per Square Foot
- Solar Panel Output Voltage
- Best Price Solar Panels Per Watt
- Solar Panel Energy Transformation
Solar Charge Controllers; everything you need to know
Solar panels have come in leaps and bounds over the last two decades, and in the camping and 4WDing world its completely changed the way people travel and enjoy themselves. A good solar panel and battery setup will allow you to run anything from fridges through to lights, water pumps and even inverters running normal 240V appliances like you would at home.
In todays post, we are looking at what a solar charge controller is, what you need to know about them and what your options are. Please know this is all referring to 12V applications, and not inverters for household use! To clear up any confusion, these are often referred to as Solar Regulators as well; its the same thing; it controls, or regulates the charge to your battery.
What is a solar charge controller?
In the camping and 4WD world, almost all batteries are 12V. This means they need to be charged at a rate that is around 12 – 14.5 volts, depending on the battery type. No solar panels output at this rate, and so you need a solar panel regulator to convert the higher voltage into something suitable for your battery.
Why do you need one?
You need a solar charge controller to charge your batteries. Without one, you’ll fry your batteries in no time. It would be similar to putting petrol in a diesel motor; its not something you can be flexible with.
What options are there for solar charge controllers?
There’s a lot of different types of solar regulators that you can purchase and use, and they will vary in price and ability dramatically. You can buy a cheap PWM regulator for 30, or a high end battery management system and DCDC for upwards of 800.
The choice is yours, and you don’t need to spend huge money, but getting something that suits what you need is important.
The cheapest solar regulator is going to be a PWM, or pulse width modulation charger. These just step the power down in the most simple way, and are a great, economical way to charge your batteries.
The next step up is MPPT, or maximum power point tracking, which is a bit smarter in the way it converts the power, and you’ll generally see better results. It’s hugely important to know that a lot of solar regulators you purchase on eBay are labelled as MPPT, and are actually not.
Much like many of the solar panels are incorrectly advertised, you need to be very careful. Keen to know more? Check this out – eBay solar panels.
A lot of people end up with an MPPT solar regulator, as they do a great job. These are stand alone solar regulators.
DCDC with solar input
If you have the ability to charge your batteries from your vehicle as well, a lot of people are going down the DCDC charger route, with a solar input. These will take alternator power and charge your batteries, or they will take power from your solar panels and charge the batteries that way.
Its important to ensure that your DCDC will tolerate the voltage from your panels, as some are higher voltage and will damage the charger. Not everyone needs a DCDC though, and if you are considering one, have a read of this; What is a DCDC and do you need one?
Factory solar regulators stuck onto the panel
You’ll see a lot of cheaper solar panels that come with regulators will have them stuck onto the back of the panel. We have a Rich Solar folding panel that we carry around like this, and its done a decent job over the years. However, its not a good idea to have the regulator stuck onto the back of the panel for a number of reasons.
Cables suffer voltage drop, and you really want your solar regulator as close to the batteries being charged as possible. If its a long way away (like when its stuck to the solar panel), you’ll find that by the time the current gets to your battery its lost some of its strength.
Electrical components should be kept cool and out of the weather as much as possible, and if you’ve ever put your hand on a solar panel in the middle of the day you’d know that they are anything but cool and out of the weather!
Ideally, you run the unregulated cables to a nicer environment near your batteries, and let them do the charging from there. That said, if it works, it works and you don’t have to change anything.
Panel sizes and wattage
Solar panels come in a huge range of sizes and wattages. You can get the normal 12V panels (18V input), or they can be 36V (like what you have on the roof of your home). Your solar panel size should suit your setup, and ensure your batteries stay healthy. importantly, the voltage needs to match your solar charger, as a huge number of solar controllers will not take higher wattage panels.
One of the most common ways to set up a cheap solar system is to use old house solar panels that you can literally pick up for under 30 each, and feed them into a solar controller that will take the higher voltage and convert it down to charge a 12V panel.
MC4 vs Andersons
A large majority of panels purchased today come with MC4 connectors. These are a black, round, plastic fitting that works pretty well (although many are fakes). The alternative is to use Anderson plugs, which are very well known and work well. MC4 connections should be waterproof, whereas Andersons can get wet and remain unaffected.
Anderson plugs are probably easier to work with, but both do the job just fine. It is worth knowing that if you cut your MC4 connectors off you can probably say good bye to any warranty that you have, and that it is possible to get MC4 to Anderson plug adapters.
Parallel or series
If you have more than one solar panel, you’ll have to decide how to link them up. The most common way is in parallel, resulting in 18V coming from the panels, but double the wattage.
For example, you could have two 100 watt solar panels, and you’d get 200W coming in at 18V. If you wire them up in series, you’d get 100W at 36V.
How you wire them up depends on your exact system and the solar controller that you are running, but you are best off sticking with Parallel unless you have reason to change. There are some pro’s and con’s to each, but parallel is far more common.
Like anything electrical, you need to ensure that the cable length and size is suitable for your setup. If you have a significant solar system, you’ll need decent thickness cables to ensure there is limited voltage drop and to ensure that you don’t start a fire with the cables getting too hot.
There’s a number of voltage drop calculators around, where you can put the amperage going through them and the cable run length, and get the correct cable size for the job. Don’t undersize it; its just not worth it.
Most solar regulators are set up to charge your standard lead acid battery, and are not able to correctly charge lithium. If you have a lithium battery, you need to ensure that the solar charger has a lithium charging profile, as its got different voltages than your normal lead acid.
Yes, you can use a traditional lead acid charger to charge a lithium; its not going to blow it up if the voltages are not too high but its inefficient, and not the right way to go about it. Drop in lithium batteries are a bit misleading in this way. to come on that on another post.
The regulator voltage needs to suit the charger
When designing a system, you should ensure that everything is compatible. What I mean by this, is that the solar panel voltages vary, and not all chargers will take all voltages. For example, house panels, and even some high wattage panels designed for 12V will not work through a number of regulators.
A lot of chargers will not take a current of over 28V, and there’s plenty of panels that exceed this, so check carefully before you commit to any parts.
Using two solar regulators
I often see people asking whether they can more than one solar regulator into their batteries. For example, if you had a 100W panel with a regulator on it, can you connect that to a battery that is also receiving charge from a DCDC via solar, or a different regulator?
The answer is yes, you absolutely can, and you won’t do any damage. How it behaves will be determined by the regulators, and they can reduce the overall efficiency when working with each other, but they will both put charge into your system.
We’ve done this many times, and our Reconn R2 is actually wired up with an Enerdrive DCDC being fed by alternator power from our 4WD and a 120W panel on the roof, and then 600W of panels feeding a Renogy Solar controller. They both feed our 340aH of lithium batteries and we have no issues with them.
Of course, you can read more about this here – can you run two controllers into the same battery?
What have we missed? What else do you want to know about solar charge controllers?
Victron BlueSolar MPPT 75/15 Solar Controller
BlueSolar 75 VOC, 15 Amp MPPT solar panel charge controller for 12V and 24V battery systems including Lithium.
SKU: VIC.SCC010015050R | MPN: SCC010015050R
Available at Victron In Stock at Victrons Australian warehouse and typically ships within 5-6 Business Days.
Shipping Included. 0.00 Delivery is typically 2 to 14 business days for In Stock items to Metro locations and longer for remote areas.
Pickup from Southport Warehouse. 0.00 We will contact you via email when your order is ready for pickup. For items In Stock this is typically within 3 HOURS.
Victron BlueSolar Controlles require the V.E.Direct Bluetooth Smart dongle. For in-built Bluetooth please view the SmartSolar range.
MPPT controllers operate solar panels at their Maximum Power Point improving efficiency up to 30% by adjusting input voltage to harvest the maximum power from the solar panels. It then manages this power to supply the varying voltage requirement of the battery plus load.
The Victron MPPT BlueSolar senses when to adjust the output that it is being sent to the battery and will shut down for a few microseconds, calculate and make relevant adjustments. The principle of MPPT is to extract the maximum possible power from a solar panel by setting the most efficient combination of voltage and current. maximum power point.
The BlueSolar supports Advanced Maximum Power Point Detection. Unlike the conventional MPPTs which tend to lock to a local MPP when shady conditions occur, [which may not be the optimum MPP], Advance Maximum Power Point Detection will harvest maximum energy by locking to the optimum MPP. In addition the unit is configured for optimal Three Step Charging.
With the V.E.Direct Bluetooth Smart dongle, programming, real-time data and history display is available on your Smart device.
Inbuilt additional electronic protection provides
Three Stage Charging
- Stage One. Bulk or Boost. As much current as possible is delivered in order to rapidly recharge the batteries to about 80%.
- Stage Two. Absorption. When the battery reaches its final charging voltage, known as its absorption voltage the charge allows the current to taper off as the battery nears a full charge.
- Stage Three. Float. At this stage float voltage is applied which is enough to retain a full charge but controlled to prevent overcharging.
MPPT 75/10, 75/15 MPPT 100/15 Specifications
Purchase with confidence knowing your product is covered by the Victron 5-year manufacturer warranty.
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What Is An MPPT Charge Controller?
The most basic functionality of a solar power system is solar panels collecting energy from the sun and storing it in batteries so that you can use it whenever you’d like. However, you can’t simply connect your solar panels directly to your batteries and expect them to charge. To get the most out of your solar panels, you’ll need a charge controller to charge your batteries efficiently. The most efficient type of charge controller is the maximum power point tracking or MPPT charge controller.
Let’s take a look at how they work and what benefits they provide.
What is Maximum Power Point Tracking?
Before we dive into how MPPT charge controllers work, let’s explain how they get their name.
The voltage at which a solar panel produces the most power is called the maximum power point voltage. The maximum power point voltage varies depending on environmental conditions and the time of day.
MPPT charge controllers get their name because they monitor the solar panel and determine the maximum power point voltage for the current conditions. This function is called maximum power point tracking, or MPPT for short.
Tip: Refresh on Amps, Volts, Watts and their differences.
What Is An MPPT Charge Controller?
Solar panels and batteries have different optimal operating voltages. Not only that, these voltages fluctuate. An MPPT charge controller is a DC-DC converter that maximizes the efficiency of a solar system. It does this by optimizing the voltage match between the solar panel array and the batteries.
For example, depending on the state of charge, a 12-volt battery has a nominal voltage that ranges between just over 10 volts and just under 13 volts. Furthermore, the voltage required to charge a 12-volt battery ranges between 13.5 and 14.5 volts depending on the charging phase.
On the other hand, the optimum output voltage of a solar panel varies depending on the panel’s temperature, time of day, how cloudy it is, and other environmental factors. For instance, under ideal conditions, a 250-watt solar panel may have an optimal operating voltage of 32 volts. As the panel heats up in the sun or on a hot day, the optimal voltage may drop to as low as 26 volts.
The rated panel voltage must be higher than the battery voltage to accommodate for these voltage drops in the panel and the increased required battery charging voltage. Without an MPPT charge controller, this voltage differential leads to a lot of wasted power.
What Is The Difference Between MPPT and PWM Charge Controllers?
To better understand how this voltage difference causes inefficiencies, let’s first examine the other common type of solar charge controller. This controller is the pulse width modulation (PWM) charge controller.
PWM controllers use a transistor switch that rapidly opens and closes as needed to regulate the charge current going into the battery. Since PWM controllers can’t modulate the voltage, they pull the output voltage of the solar panel down to match the battery voltage. Let’s look at an example.
A 250-watt solar panel may have an optimal or max power voltage (Vmp) of 32 volts and a max power current (Imp) of 7.8 amps. (32 volts x 7.8 amps = 250 watts)
Using a PWM controller, your panel will still produce 7.8 amps. But the voltage will drop to match the battery at 12 volts. Now, your panel is only providing 94 watts instead of 250 watts. (12 volts x 7.8 amps = 94 watts)
How MPPT Charge Controllers Work
As we mentioned before, MPPT charge controllers are DC-DC converters. This means they regulate the charge current into the battery like a PWM controller. But, they also convert the voltage coming out of the panel to match what the battery needs. Let’s look at an example of how this drastically improves efficiency.
Using the same 250-watt panel, the MPPT controller allows the panel to operate at the max power voltage (Vmp). Now the power going into the controller is the full rated 250 watts.
The output from the controller to the battery still needs to match the battery at 12 volts. But the current increases to 20.8 amps allowing you to utilize the full 250 watt potential of your panel. (12 volts x 20.8 amps = 250 watts)
For simplicity, these examples assumed a 100% efficient conversion in the charge controllers. In reality, a small amount of power is lost as heat during the conversion.
Benefits of an MPPT Charge Controller
Efficient at Using Power
On a properly sized solar power system, it’s not uncommon to see up to a 30% increase in efficiency by switching to an MPPT controller. This efficiency increase is even more significant on systems where the solar panel voltage is much higher than the battery voltage, like our example above.
Best for Large Systems
Utilizing an additional 20-30% of power out of your system becomes more advantageous as the size of your system grows. For this reason, MPPT controllers are often best used on large systems and may not be worth it on smaller, simpler setups.
Better in Cloudier Environments
The maximum power point tracking feature of MPPT controllers is a huge benefit in cloudy environments where the max power point of the solar panels will be fluctuating all day.
Are MPPT Solar Charge Controllers Worth It?
MPPT charge controllers are more expensive than PWM controllers. The added cost of upgrading your controller may not be worth it on small, basic systems. However, on larger systems or in locations with unstable weather conditions, the increased power and efficiency gained by using an MPPT controller will likely more than makeup for the added cost of the controller.
Nobody likes to waste power. MPPT charge controllers help you get the most out of your solar panels without worrying about changing weather conditions or making sure you perfectly sized your solar panels to your battery voltage.