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Best Solar Power Bank for Backpacking. Outdoor solar USB charger

Best Solar Power Bank for Backpacking. Outdoor solar USB charger

    We Tested a Rugged USB Power Bank with Quick Charge Capabilities, Emergency Flashlight, and a Built-In Solar Panel

    Written by Patrick McCarthy on November 4, 2018

    We’ve often heard back-and-forth discussion in the survivalist community about the true meaning of going off-the-grid. Many will say that the term means immediately abandoning all electronic devices. We can understand this sentiment, since a worst-case off-grid situation would leave you completely and permanently disconnected from modern infrastructure. That means no internet, no cell signal, no GPS, no radio or TV reception, and no access to electricity at all.

    Although this is possible and certainly something you should be ready for, bear in mind that this definition is a worst-case scenario. It’s much more likely that your off-grid situation will only affect some of these modern conveniences, and will only result in a temporary lapse in service. Maybe you’re hiking in a remote location and find that you’re out of range from cell towers, or maybe a severe storm leads to a city-wide blackout. In any of these intermediate cases, you won’t want to ditch your cell phone, GPS unit, or LED headlamp — instead, you’ll need to keep them going for the hours, days, or weeks until your situation improves and their functionality returns.

    Without a flashlight, your ability to navigate or work at night will be severely limited.

    A USB power bank is one of the most valuable assets for the task of keeping your small electronics running without direct grid access. Much like a stockpile of food to maintain your physical strength or a reserve fuel tank to keep your vehicle running, a power bank provides an instant backup electricity source. This is especially helpful given the prevalence of USB-rechargeable devices. These days, it’s easy to run all the electronics in your get-home bag on this universal system with the aid of a few different cables.

    The Solar Advantage

    A good power bank provides a short-term source of juice, but like any other battery it’s bound to run out eventually. When charging from a wall outlet or a vehicle’s 12V socket isn’t an option, supplementing your power bank with a solar panel is a wise choice. With a solar panel, you can recharge your devices from the battery, and recharge the battery from the sun. Now your temporary backup just became a long-term solution.

    Admittedly, the most effective solar panels are huge, expensive, and sensitive to weather conditions, and even these are unlikely to recharge your power bank as fast as a wall outlet or car charger. Smaller portable panels offer lighter weight and more durability, but they’ll require several days of full sun to recharge a power bank. Solar isn’t always the most convenient power source, but if it’s the only one you’ve got, you’ll definitely be glad to have it. This is why we always make a point to have some type of lightweight solar panel in our bug-out and camping gear loadouts.

    RAVPower 25,000mAh Solar Power Bank

    We recently had the opportunity to test a power bank from RAVPower, namely the Exclusives 25,000mAh Solar Power Bank. This outdoor-oriented unit features a reasonable 50 retail price, and a huge capacity of 25,000 milliamp-hours (mAh). That’s enough to fully recharge these devices the following number of times:

    • iPhone 8 – 9.3 times
    • Samsung Galaxy S8 – 5.6 times
    • iPad Mini 4- 3.3 times
    • Nitecore HC65 headlamp – 7.4 times
    • Garmin InReach Explorer GPS unit – 8 times

    So, if you head out into the woods with this power bank, you should be able to maintain your portable devices for a week or more of normal use.

    The RAVPower 25,000mAh power bank also features an integrated 5-volt / 300 milliamp solar panel. It features a green LED indicator in the top left corner that lets you know when the panel is receiving sufficient sunlight. Under ideal conditions, RAVPower says the panel will replenish the 25,000mAh battery in 85 hours.

    The solar panel is recessed and protected by the power bank’s rubberized case, which is impact-resistant and IP66 waterproof and dustproof. It also features indentations on the sides and ridged corners for added grip and impact protection. At the bottom of the case, there’s also a folding metal loop where an included carabiner can be used to attach the power bank to your backpack or other gear while the solar panel does its thing.

    A total of four USB ports are located on the power bank:

    The first two smaller USB ports are on the side of the case, while the other two full-size USB ports are on top. Both pairs are protected from the elements by rubber flaps, maintaining the waterproof/dustproof rating when they’re not in use. RAVPower designed the power bank with Quick Charge and iSmart compatibility, which deliver up to 3 amps to maximize the charging speed for compatible Android and Apple devices. It can also provide up to 5V/6.4A through the three output ports to charge three devices at full speed at the same time.

    There’s another trick feature on this power bank’s input system that allows it to be charged through either the Micro USB port or the USB-C port, or through both simultaneously. This means you can push up to 4 amps of juice into the device by using two wall sockets and two 2A chargers (or one outlet with multiple 2A ports). The graphic below from RAVPower compares the recharging speed for all three of these options:

    On the back side of the power bank, you’ll see the clearly-labeled on-off button as well as four blue LEDs. These LEDs indicate the battery level while the unit is being recharged, charging other devices, or if the user taps the power button.

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    Here’s a chart that shows how to interpret these readings as a precise battery level:

    The last noteworthy feature of the power bank is its integrated LED flashlight. Pressing and holding the power button for 3 seconds activates the light, and additional short presses cycle between constant, slow flashing, and SOS modes. RAVPower doesn’t advertise an output rating for the light, but we’d estimate it’s around 100 lumens. The relatively-wide beam pattern makes it useful for map-reading and other up-close tasks.

    Our Impressions

    We carried the RAVPower 25,000mAh Solar Power Bank around in a pack with the rest of our EDC electronics kit. Our standard kit includes various USB cables as well as a 2.4A wall charger, a 12V cigarette lighter adapter, and a few other small items. Until we received the 25,000mAh power bank, we had been using a RAVPower 16,750mAh unit that served us well for several years.

    Compared to the previous setup, our new power bank upgrades our battery capacity by 33%, and also adds valuable solar capabilities. The integrated flashlight is also much more useful with its larger lens and brighter output. Weight is a drawback, since its 19.4-ounce weight is nearly double that of our previous power bank.

    We appreciate the clear LED charge indicators, both for the solar panel and the battery level. Finding full sunlight for the solar panel is easy, since the green LED dims smoothly depending on the quality of ambient light. If it’s shining brightly, you’re good to go. However, even in full sunlight, it recharges the battery slowly. In the bright Arizona desert with a cloudless sky, bringing the battery level from about 50% to 100% took more than 48 hours. But as we said earlier, when there’s no other power source, this solar panel could be a life-saver.

    Charging small devices such as an iPhone is quick and easy, and the iSmart system produces optimal 2.4A current for replenishing these Apple products at full speed. Resurrecting a phone from a nearly-dead battery will barely put a dent in the 25,000mAh capacity. Android devices can receive as much as 3A, which is also ideal. We don’t currently have any devices with Qualcomm Quick Charge functionality, but it’s a nice option for those who do.

    Although the power bank comes with two short Micro USB cables and a carabiner, a wall charger is not included. RAVPower sells these separately, but we were still disappointed by this omission, especially since other power banks we’ve ordered typically include this accessory. It would’ve been helpful if RAVPower threw in a compact high-speed wall charger with two USB ports so we could max out the 4A input — we’d be willing to pay a bit more for this complete package. For now, we’ll have to rely on the Apple 2.4A charger that’s already in our EDC kit.


    The RAVPower Exclusives 25,000mAh power bank is a solid choice for EDC, backpacking, or survival. Its tough water- and dustproof case held up to outdoor use aside from a few cosmetic scuffs, and its solar panel provides a tremendous advantage for long-term use while you’re away from the grid. The flashlight and carabiner hanging system are also nice touches. Most importantly, the 25,000mAh capacity is massive, and had no trouble maintaining multiple devices during longer excursions.

    Value is quite good at the 50 MSRP. but we’ve got some good news. RAVPower provided us with a 35% off discount code for RECOIL OFFGRID readers, and this brings the price down to 32.50. For the record, there’s absolutely nothing in it for us if you buy this product or use this code. We’re just passing it along so anyone who wants one can save some money. That said, if you’re interested in one of these power banks, you can enter code PB35OW on RAVPower’s web site to get the discounted price — this offer is only valid through 11/24/2018. [Update: A RAVPower company representative has informed us that its web site’s “code system met some problems, so all codes don’t work these days”. We’re told their staff is working on the problem but they don’t know when it will be resolved, and they apologize for the inconvenience. If we receive another working discount code from RAVPower, we will update this article accordingly.]

    To summarize, here are some pros and cons based on our experience with this power bank:

    • Rugged, waterproof, dustproof, impact-resistant exterior
    • Solar panel adds off-the-grid versatility
    • Multiple outputs allow charging up to 3 devices at full speed
    • Dual-input design can dramatically speed up recharging
    • Good bang for the buck especially at the discounted price
    • Lacks a wall charger, so you’ll need to buy one separately
    • Quite heavy at 1.2 pounds
    • Even with clear and sunny skies, the solar panel takes several days to recharge the battery
    • LED flashlight could be brighter

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    Best Solar Power Bank for Backpacking

    Raise your hand if you have ever gone off-grid and grudgingly spent several days without contacting your loved ones. While backpacking is always fun and therapeutic, navigating the unknown with uncharged gadgets like smartphones and GPS devices can dampen the excitement. This is why investing in the best solar power bank for backpacking is a must before your next outdoor activity.

    Overall Best Selling Solar Power Bank for Backpacking

    Quadrapro Solar Power Bank With Wireless Dual USB Charging By Frog Co By Frog Co.

    Whether you’re in need of some extra power to call for a rescue or you just want to post a picture of a gorgeous view, we believe you should be able to harness the free power of the sun. With a built-in power bank, it offers a compact design that can trav

    You might agree that the only constant about the outdoors is the unpredictability of the power supply. Hence, you might still have dead batteries when using electricity-powered power banks. However, you can find the best backpacking solar power bank that is convenient, efficient, portable, and versatile.

    In today’s article, we present to you the best solar power bank for backpacking. We also delve deeper by considering lightness and capacity, among other questions you might have for a successful power-charged backpacking endeavor.

    Best Power bank for Ultralight Backpacking

    Not all backpacking is the same, as some require you to carry only the lightest and tiniest gear. With that, ultralight backpacking renders your bulky power banks impractical, requiring only the featherweight options.

    Here are the best power banks for ultralight backpacking that we recommend:

    QuadraPro Solar Power Bank

    A first visual impression of this power bank may have you thinking it does not pack much. However, it is the one thing you need to have your gadgets charged up during your weeks-long backpacking. Here are the reasons why we recommend it as the best solar charger power bank for lightweight backpacking:

    Water Resistant, Drop, and Shock-proof

    Nothing compares to the heartache of having your power bank ruined by a few drops of water during backpacking. Oftentimes, people have had to pause their backpacking activity after water damage. The QuadraPro solar power bank is waterproof, so you can use it even when it’s raining. How cool!

    Additionally, the manufacturers made this knowing that accidents are inevitable in the outdoors. You can drop this solar power bank and pick it up like nothing happened since it has panels protected with a thin sheet of sturdy plastic. Besides, its edges and the back have a grippy and tough silicon coating for a more secure grip.

    It is Compact yet Lightweight

    This gem has come to your rescue if you still have to count the stars waiting for one gadget to charge before starting another. The QuadraPro solar power bank weighs only 13.1 ounces but charges up to 3 devices concurrently with the dual charging ports. Extra points for you if you have a wireless device since all you need to do is place it on top for the QuadraPro solar power bank to do its magic.

    Owing to its incredibly lightweight and compact size, you can slide it into your side. purse, or glove compartment for an effortless backpacking experience.

    Convenient Charging

    This bad boy also has built-in magnets you can attach to a metal object like your off-grid truck for convenient and safe charging. Its sturdy carabiner also lets you hook it on your back and get free power on the move. It is hands-down the best solar power bank for backpacking.

    Besides this, you do not need to worry about it dying unexpectedly since placing it in the sun or plugging it in automatically reveals how much charge it has.

    Comes with a Big Backup Battery

    The QuadraPro solar power bank packs pleasant surprises, including a 6500 mAh battery. Don’t get me wrong: the solar power bank in itself is a beast that can withstand multiple power refills to your gadgets. However, the backup battery lets you charge your batteries over three times when the sun is playing hide-and-seek or when you just completely forgot to put it out in the sun to charge.

    Comes with a Built-in LED Flashlight

    How many of us are scared of the dark, especially on an unfamiliar trail? The QuadraPro solar power back proves to be the best backpacking solar power bank since it has a 50-lumen built-in flashlight. It becomes convenient when you need to light up a room, a campsite, or a trail.

    DIY Solar USB Charger: 7 Steps (w/ Photos)

    Just so you know, this page contains affiliate links. If you make a purchase after clicking on one, at no extra cost to you I may earn a small commission.

    I recently made a DIY solar USB charger that, in my opinion, is WAY better than most of the other designs out there.

    It’s portable. It looks good. And it can charge your phone and USB devices faster than the mere trickle put out by most other homemade solar chargers.

    That’s right — it’s a DIY solar charger that you’ll actually use.

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    It’s affordable and easy to make.

    Materials Tools


    • 2 3W 9V solar panels
    • 22 gauge stranded wire
    • 5V DC/DC buck converter
    • E6000 craft glue (a hot glue gun is pictured, but this is what I ended up using)
    • Reusable grocery bag
    • Heat shrink tubing (optional)
    • 4 1/4″ eyelets (optional)


    • Wire strippers
    • Soldering iron
    • Scissors
    • Safety glasses
    • Multimeter
    • Heat gun (optional)
    • 1/4″ eyelet tools (optional)
    • Hammer (optional)

    Step 1: Prep the Fabric

    For this design, I upcycled an old reusable grocery bag to cut a strip of fabric to which I attached the panels. It protects them and allows them to fold up for easy storage.

    Place the panels, eyelets (if using), and DC/DC buck converter on the reusable grocery bag in your desired layout.

    Tip: I recommend giving yourself 1″ or more of space between your solar panels so they can fold easily. I also gave myself more length than necessary so I could fold the fabric over the buck converter, as you’ll see in Step 6.

    Cut the fabric to your desired dimensions with scissors. (Mine ended up being about 14″ long by 8.25″ wide.)

    Step 2: Wire the Solar Panels in Parallel

    Cut a length of wire to connect the panels’ positive terminals. Give yourself some slack in the wire so it isn’t pulled taut when the panels are folded.

    Note: Because my panels have two pairs of terminals on back, before wiring I used a multimeter to check their voltages. It turned out the terminals that output 9 volts are the two “top” terminals — not the terminals with the “” and “-” signs. Strange.

    Strip and solder the wire from positive terminal to positive terminal. (I decided to orient my panels in opposite directions to lessen the stress on the wire when the panels are folded.)

    Tip: Keep your solder joints as flush as possible with your solar panels. This helps later on when gluing them to the fabric.

    Cut a length of wire to connect the panels’ negative terminals. Once again, give yourself some slack.

    Strip and solder the wire from negative terminal to negative terminal.

    Step 3: Solder the Leads to the Panels

    Cut a length of wire for the panels’ positive lead. It will connect one of the panels’ positive terminal to the buck converter’s positive terminal. Make sure it can reach where you want to place the converter. Don’t forget some slack!

    Strip and solder the positive lead to one of the panels’ positive terminal.

    Cut a length of wire for the panels’ negative lead.

    Strip and solder the negative lead to one of the panels’ negative terminal.

    Now let’s test the panels’ voltage and amperage outputs with a multimeter to make sure we wired everything correctly! Connect the meter’s positive probe to the positive lead and its negative probe to the negative lead.

    What outputs should we expect?

    Well, here are the specs for the panels I used:

    Wiring solar panels in parallel adds the current (amps) together while keeping the voltage (volts) the same.

    Thus, for volts, you should see a number around 9V DC.

    For amps, you should see a number around 666mA (333mA 2). But in real world conditions, expect solar panels to output a little less than their stated current.

    Tip: You’ll likely have to switch the red probe to your multimeter’s other port in order to measure this amount of current.

    Step 4: Solder the Buck Converter to the Leads

    Locate the positive and negative terminals on the buck converter.

    Solder the positive lead to the converter’s positive terminal and the negative lead to its negative terminal.

    Now you should have a working solar charger!

    Time to check that it’s working.

    First, make sure the buck converter is connected properly and working by shining some light on the panels. Its LED should light up.

    The LED is on. Looks like it’s working.

    Next, test your charger by placing it outside in direct sunlight and plugging in your phone or USB device. Your device should start charging.

    My Kindle’s charging light turns on when I plug it in — my charger is working!

    I tested my charger’s output with a USB meter to confirm that the charger was indeed outputting a decent current at 5V.

    best, solar, power, bank, backpacking, outdoor

    It’s outputting 460 mA (about 0.5 A) at 5V. That’s about 2.5W, or half the rate of a standard 5W phone charger. (During real-world use it regularly got up to 3W.)

    According to our solar charging calculator, it will take about 5.7 peak sun hours to fully charge my iPhone XR.

    Definitely not the fastest solar charger, but it’ll top off my battery in a pinch.

    Optional: Shrink wrap the buck converter using heat shrink tubing and a heat gun. I did this to for aesthetics and to protect the circuit board a bit. It covers up the converter’s LED, but that wasn’t a big deal to me.

    Step 5: Glue the Charger to the Fabric

    Grab your glue and the strip of fabric you cut back in Step 1. Glue the panels and buck converter to the fabric in your desired layout.

    Tip: The glue I used bled through the fabric a bit, so you may want to put a piece of newspaper down first.

    Wait for the glue to set. Once it has, touch up any spots you missed, if needed.

    Step 6: Install the Eyelets (Optional)

    Because I’ll be using my charger while hiking and biking, I wanted to install eyelets so I can strap it to my backpack and bike. If you don’t need to attach your charger to anything, you can skip this step.

    First, let’s install the two eyelets at the “bottom” — the side opposite the buck converter.

    Cut a circle in the fabric using the eyelet as a guide. Feed the eyelet bottom through the hole.

    Tip: Since I used such small eyelets I just cut a small X with my scissors. You could also create a hole by poking a nail through.

    Place the eyelet base tool underneath the eyelet bottom. Place the eyelet top on top of the fabric.

    Place the eyelet punch tool over the eyelet top. Hammer the punch tool to install the eyelet.

    Repeat these steps to install the second bottom eyelet.

    Now it’s time for the top eyelets — the ones on the same side as the buck converter.

    To protect the converter, I decided to fold the extra fabric over it and cut a hole for its USB port. (If you don’t want to do that, just install the top eyelets like you did the bottom ones.)

    Then I installed the top eyelets through both layers of fabric, glued the flaps together, and glued the USB port to the fabric.

    Note: Don’t cover up any of the solar panel!

    Wait for the glue to set, and you’re DONE!

    Step 7: Test Your DIY Solar Charger

    Now that you’ve made your own solar-powered charger, it’s time to charge something with it!

    Place it outside in direct sunlight. Plug in your phone or other USB device. Then sit back and relax as you take advantage of all that free solar energy.

    When you’re done charging, fold the charger shut for easy storage.

    This charger doesn’t have a built-in battery. Adding a battery makes a homemade solar phone charger more complex.

    You can easily pair your charger with your battery pack of choice (I use the Anker PowerCore 10000). Charge your battery pack during the day, then use it to charge your phone or USB device at night.

    DIY Solar Charger Projects

    Solar Electric Bike Charger

    Learn how to solar charge your ebike battery for what may be the most eco-friendly transportation method there is. I even show you how I mounted my solar charger to my ebike to make a full-on solar bike.

    Solar USB Charger

    About: Making and sharing are my two biggest passions! In total I’ve published hundreds of tutorials about everything from microcontrollers to knitting. I’m a New York City motorcyclist and unrepentant dog mom. My wo… About bekathwia »

    Let’s make something super useful— your own solar powered USB backup battery! After some simple soldering, you’ll be ready to charge your phone and other portable electronics on the go while camping or during the next power outage. What follows is a basic recipe which you can follow exactly, or switch out the solar panel and battery size to match your desired capacity, charge speed, and budget.

    This project is part of my free Solar Class, where you can learn more ways to harness the sun’s energy through engraving and solar panels.

    To keep up with what I’m working on, follow me on YouTube, Instagram and subscribe to my newsletter.

    Step 1: What You’ll Need

    As an Amazon Associate I earn from qualifying purchases you make using my affiliate links.

    First soldering project? No problem! This is a great project for beginners, and you’ll get a variety of types of solder practice while building it. You can learn how in the soldering lesson of Randy’s free Instructables Electronics Class, then come back here to assemble your solar charger.

    Step 2: Circuit Diagram

    The solar charger circuit board comes with a USB port, DC jack for the solar panel, and two JST ports already attached to the board. The battery comes with a JST plug and will attach to the JST port labeled BATT. The solar charger comes with a JST pigtail cable which will connect to the LOAD port and be soldered directly to the PowerBoost input terminals.

    The power switch (at the top of the diagram above) should be attached to the PowerBoost pins labeled EN and GND. Flipping it will turn on and off the PowerBoost. This switch does not have to carry the circuit’s current load, so choose almost any on/off switch you like. I chose an illuminated on/off pushbutton, which also needs to be connected to the PowerBoost’s 5V and GND pins, with a 220ohm resistor in series. The illuminated portion of the switch is optional, but it is a nice indicator that the device is ready to charge your USB devices.

    Step 3: Test Fit Components

    You’ll want to pick an enclosure that fits all your components snugly, without too much squishing. I had an extra Moo business card box that fits the length of the battery and the height of the solar charger perfectly, and even has a little extra space left over for business cards still.

    It closes with magnets embedded in the layers of cardboard and paper. If you can’t find a stiff paper/cardboard box, you can choose an enclosure made from wood, plastic, or metal, however these harder materials will require different tools for creating port openings, such as a drill with a step bit.

    In addition to physically fitting inside, you must also plan out where to create the openings so that your device is useable. I chose to put the illuminated power button next to the USB port, since the light indicates it’s ready to charge. This area of the box is recessed, making the button less likely to get accidentally triggered while the device is in my bag. Opposite the button and USB A port (PowerBoost) are the solar panel DC port and USB mini B port (solar charger).

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    Step 4: Solder Capacitor to Solar Charger

    The solar charger board comes with most of the components soldered to the board already, with the exception of the large filtering capacitor. Look for the large circle on the circuit board, with holes matching the capacitor’s lead spacing.

    The capacitor’s polarity is important! The negative side of the capacitor is labeled with a white stripe and minus symbol, and the negative lead is typically shorter. The positive side of the capacitor is not labeled, and the leg is typically longer.

    Line up the positive lead to the hole marked. and the negative lead to the hole marked

    If your enclosure doesn’t have enough space to fit the height of this large capacitor, you may bend it over slightly before soldering, or use wires (and heat shrink tubing) to move it to another part of your enclosure. According to the official assembly instructions, you should be careful to avoid contact with the hot chip in the center of the board.

    To learn how to solder, check out the soldering lesson in Randy’s free Instructables Electronics Class.

    Step 5: Assemble PowerBoost

    Install the USB port to the PowerBoost circuit board, and be sure it is seated completely and evenly before soldering the terminals to the board on the underside.

    The large clip joints connecting big areas of metal will require longer heating and more solder other solder joints. Allow to cool in your third hand tool for several minutes before attempting to handle the USB port, as it will get very hot.

    Although the PowerBoost comes with two different connectors for its input power and ground terminals, we’re going to leave those off and solder the JST pigtail wire directly to the circuit board.

    Heat up and tin the ends of the wires and the pads marked and Reheat the pad and wire as you bring them together: red to and black to

    Step 6: Mark Cut Port Openings

    Now that your circuit board elements have taken their final shapes, it’s time to mark and cut openings for the ports in your enclosure.

    Arrange the components inside your enclosure as you did during test-fit, and trace around the ports and power button using a pencil or marker.

    If you’re using double-stick foam tape instead of screws to secure your components, adjust the markings to accommodate for the width of the tape.

    Carefully cut the openings with a sharp craft knife. If you’re not using a paper box (for example plastic, metal, or wood), you may need a drill with a step bit, rotary tool with cutoff wheel accessory, small hacksaw, or other cutting tools appropriate for the material. If you’re using a metal enclosure, line the inside with adhesive vinyl, thick tape, or other insulating material, to prevent short circuits.

    Step 7: Connect Power Switch

    My switch has a threaded plastic ring that will secure it to the enclosure, so I removed that first.

    Tin and solder wires onto the leads of your power switch, and use heat shrink tubing to insulate the connections.

    Since my switch has an internal LED, I’m also wiring up a 220ohm resistor to one of the leads (doesn’t matter which), then a wire onto the opposite resistor lead. The LED is optional— you can leave it off or use any on/off switch you like (such as a toggle, slide switch, or tactile on/off button).

    This on/off switch must be installed from the exterior of the enclosure, and therefore must be installed before we can solder the other ends of the wires to anything.

    Insert the switch with wires through the opening in the enclosure, and thread the nut back onto the switch and tighten it against the inside of the enclosure.

    After the switch is in place, you can solder its wires to the various pins on the PowerBoost board as described in the circuit diagram. The LED is connected to 5V (LED ) and GND (LED.), and the switch leads are connected to EN and GND. To attach each wire, trim it a little longer than you think you’ll need, then strip off a bit of the insulation. Twist the wire strands together and lightly tin the wire so the strands stay together. Insert the tinned end into the hole on the circuit board, and apply heat and solder to connect. Trim the remaining wire end with flush snips, but be careful not to let bits of loose wire get stuck inside your enclosure.

    Step 8: Secure Components Within Enclosure

    Before securing the boards, let’s test out the circuit! Plug your PowerBoost’s JST pigtail cable into the LOAD port on the solar charger, and your battery into the BATT port.

    Toggle your power switch, and the PowerBoost’s onboard LED should light up, as well as your power switch LED if you have one. If yours doesn’t, toggle the power back off, disconnect the battery, and double check your wiring against the circuit diagram, as well as the integrity of your solder joints. Post a photo in the Комментарии и мнения владельцев if you still can’t get it to work after these troubleshooting steps.

    Further check that plugging in a USB cable to the solar charger triggers the battery to start charging, as indicated by the amber CHRG LED on the circuit board, as well as the red DCIN LED when power is connected. Verify that the battery keeps charging even when you toggle off the PowerBoost’s switch. Rechargeable batteries usually ship charged, but if you’re using a battery from a previous project or unknown origin, you may need to let it charge for a while before use. When it’s finished charging, the green LED on the solar charging board will light up.

    It’s better to find any wiring mistakes or cold solder joints now, before attaching everything inside the enclosure. After you’re sure the circuit is working properly, use screws or double stick foam tape to secure the circuit boards to the enclosure. I used double stick foam tape to hold the battery in place, too.

    Step 9: Power Up!

    Close up your enclosure and take it outside on a sunny day! Plug in your solar panel with a DC barrel jack adapter. The panel will charge up the battery and power the LOAD port at the same time, if it is getting enough direct sunlight.

    You can put it into charge-only mode by powering down the PowerBoost. Later when your phone’s battery is getting low, you can plug in and power it up.

    Consider mounting your solar panel on your backpack to charge the battery while you’re outside, or find a sunny spot outside a window at home. Be careful if you decide to mount a solar panel to the roof of your car (and consult a professional if you need help to mount it safely).

    Step 10: Make It Your Own

    You may wish to extend or change the connector on your solar panel’s wire. After all the soldering you already did to get this far, splicing the cable is no big deal. If you have the extra time, go for it! There’s a step-by-step guide in the Solar Panels lesson.

    You can expand the capacity of this charger by using a bigger battery, and speed up its charge rate with a bigger 6V solar panel.

    If your battery is above 1000mAh and you’re using a big panel, you can increase the max charge rate of the board by soldering a 2.2K resistor across PROG, as detailed in the official product guide.

    If you want to charge your battery unattended, it’s Smart to install the solar charger’s optional thermistor. First clip off the surface mount resistor inside the marking labeled THERM.

    Trim the probe wires to an appropriate length to reach your battery inside your enclosure, then strip, tin, and solder the wires to the holes marked THERM on the solar charger board.

    Use tape to connect the probe to the surface of your battery. This prevents the device from charging while the battery is too hot or too cold.

    I’d love to see your finished USB charger in the Комментарии и мнения владельцев! Are you taking it to the beach? Adding it to your hurricane kit? Tell us about your version and enclosure. Thanks for following along!

    This project is part of my free Solar Class, where you can find another backyard project and several lessons on working with solar panels. Check it out and enroll so you can post photos of your builds!

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