Here’s a DIY solar powered battery bank I built a few years back, specifically to be waterproof for camping.
I’ve used it several times to run my 12 volt fan, which is small enough to hang in my tent, but still big enough to keep the entire tent’s air moving. It also powers my USB Edison LED lights to keep the tent’s exterior and surrounding area lit up, so we can still enjoy the campsite once the sun is down.
On occasion I also may plug my phone up to charge when the sun is out and providing free electricity. And theoretically it could also be used to jump my car battery, were that to fail at the campsite, away from civilization.
This DIY solar battery bank is waterproof
I know there are a lot of similar projects already out there, but mine is a little different in that it’s designed to fit in a waterproof ammo box, that can handle the weight of the batteries with ease.
It’s easily transportable and takes up little precious space when packed to camp. Check out the pics, then I’ll list the specs and the parts to help you guys replicate this for your next trip:
DIY Solar Powered Battery Bank Specs
It’s been a few years since I built this, but at the time, I did run the calculations then to make sure all the components of the system are compatible with each other. The solar panel’s voltage and amperage are compatible with the charge controller, batteries, wire gauge, and fuse size.
Such ensures the batteries won’t overheat and/or off-gas (they’re actually sealed) from too much wattage, and the charge controller will accept the power input from the panel and the loads I’m using (fan, phone and lights). I’ve never blown the fuse either. So if you just stick to the part list I’ll publish below, you should be able to make a bank that works good for similar loads.
FYI: The links to the parts for this project mostly go to Amazon.com and are my affiliate links. Some go to Home Depot, when Amazon didn’t have a particular part you need, to complete the project. Just a heads up, so you know your not clicking into some weird place on the internet!
Battery Specs
The Mighty Max Sealed Lead Acid, AGM battery is 12 volts, and has a capacity of 18 amp hours or 216 watt hours. It’s electrolytes are embedded in a glass mat so that the battery won’t spill and you can mount the battery in any position you’d like. For this project, I of course put them in the ammo box right side up. The battery is also sealed so that it won’t off-gas under normal operating conditions. I used 2 of these batteries and hooked them up in parallel in order to create a 12 volt, 36 amp hour or 432 watt hour battery.
10 AWG wire (both black and red) with insulated ring terminals was what I used to create the parallel connections. I bought both the ring terminals and the wire at Home Depot. The batteries come with their own nut/bolt/washer sets to make the connections (though the Amazon page for the battery doesn’t clearly state this).
As long as you store your battery at home at hospitable temperatures (batteries like the same temps as humans) this brand will provide hundreds of cycles. When they are brand new, they may have a self discharge rate of 1 or 2 months from 100% to 50% charge. Mine are 3 years old, and it looks like it takes around 2 or 3 weeks to get to 50% depth of discharge (DoD) at an average temp of 78F. The charge controller will tell you what your current DoD is by publishing the voltage it’s getting from the battery on its home screen. See the chart I’ve posted below to find the charge % as a function of this published voltage.
What I do to recharge the battery up to 100% at home, is use a 5 amp trickle charger with alligator clamps. The brand I use that works good with this system is the BMK 12V 5A Smart Battery Charger. It knows when to stop charging when the battery is full so you could keep it plugged in all the time and it won’t hurt the battery. I just plug mine in every 2-3 weeks now, just to get the battery back up to 100%, then I unplug it. I put the clamps right on the battery terminals (red on one battery, and black on the opposite battery).
The charge controller will register 13 volts (or more) when the battery is 100% charged. As the battery naturally loses charge, it should be charged once the voltage gets in the low 12 volt range (12.1V). Never let the batter go under 12 volts as it will reduce its lifespan and you will have to buy a new set of batteries. However it’s only around $80 to change out the batteries; a lot cheaper than buying one of those pre-made units (Goal Zero) and having to spend another $400-500 for a new unit.
Solar Panel Specs
The Weize 100 Watt Solar Panel is nominally 12 volts (up to 18.78 volts at max output according to the labeling) and thus will work with the charge controller and the batteries. At max power it can provide 5.32 amps according to its labeling, though I’ve recorded up to 5.6 amps in real world use of the system.
Because lead acid batteries should not be discharged more than 50% of their capacity, our 36 amp hour battery should not be discharged more than 18 amp hours. Thus charging at nominal max output of the solar panel, it should take about 3 hours and 22 minutes to fully charge the battery. This short charging time is critical out in the field, where there may be tree related shade, and you have to keep moving your panel around to keep it in the sun, as it moves through the sky, or there may be clouds in the sky and 5 amps of power is not achievable, etc.
The cords coming off the back of the solar panel have mc4 male and female connectors on their ends.
Charge Controller Specs
The ALLPOWERS 20A Solar Charger Controller is capable of handling 20A of load, and 20A of solar power through it and into the battery. As I’ve just explained, my solar panel won’t go over 6A and the max load of my fan, if I recall, is 3A, or a little above that, on its highest setting. Here’s a pic I took when it was running the fan on, I believe, its middle setting, where it was drawing only 1.6A:
The load of the LED lights I use when camping is nothing to mention as they have such a small draw. And thus my loads aren’t anywhere near what the max capacity of the charge controller are.
The unit is capable of handling AGM, Open and Gel type lead acid batteries, and make sure you scroll through the menus, using the left most button on the controller, to the battery option menu, then use the + or – buttons to select B02 to tell the controller you’re using AGM batteries like I did in this project. Note: the unit will not work with a lithium battery, so don’t expect to be able to upgrade your system later, if you’re currently trying to replicate mine.
The charge controller does allow you to set a minimum battery voltage for it to power any loads, and thus you can program it to shut off any power usage beyond a given battery charge level. This means if you leave your fan on at night, the controller will turn it off for you before the battery gets too low to cause damage. And if you’re using the USB port on the controller for lights, there is a timer you can program, but I never use that function.
Wire Specs
The wiring I’m using is 10 AWG and 12 AWG. The 10 AWG is for the parallel connections on the batteries, and for the DIY solar panel cord, that goes from the mc4 connectors to the fuses that continue on to the Anderson Powerpole connectors at the end of the cord. The 12 AWG connects the batteries to the charge controller (there’s actually a fuse on the positive side, where the 12 AWG from the battery connects to the fuse’s 12 AWG wire on one side, then the fuse’s wire on the other side goes into the charge controller). The 12 AWG also connects the charge controller to the socket panel and further makes all the connections between the four units in that panel.
Wiring Diagrams and Parts Lists for DIY Solar Powered Battery Bank for Camping
I’ll first go over the parts needed for each component of the solar powered battery bank, then I’ll post a wiring diagram.
Extension Cord Parts List
To make the extension cord that goes from the solar panel’s mc4 connectors to the Anderson Powerpole connectors that attach to the wire going into the charge controller, you’ll need the following:
mc4 Connectors and Crimping Tool
BougeRV Solar Connectors Tool Kit – this product comes with several male and female mc4 connectors and a crimping tool to connect them to your Home Depot 10 AWG wire. You will need to crimp a male and female mc4 connector onto the end of your positive and negative wires to connect the extension cord to the solar panel.
Wire
Home Depot 10 AWG wire. Get both red and black colored wire. For direct current wiring the red wire is the positive or hot wire, and the black wire is the negative. You don’t have to buy the pre-cut lengths at Home Depot either; you can ask the attendant to cut whatever length you’d like. Mine are long enough to have the solar panel in the sun and have the battery bank in the shade, where it likes to be – like in the tent’s vestibule or shady side.
Fuses
SENSTREE 12 AWG Gauge ATC/ATO Fuse Holder (inline waterproof fuse holder and wire) – this is just a wire with a fuse plug in the middle of it, such that you can insert different fuses based on the max amperage you want the wire to carry. I put 7.5A fuses (comes with the product) in mine. I also put one fuse on both the positive and negative side, and I think I did this because the wires that come with this product fit the Anderson Powerpole connectors better than just the plain Home Depot wire.
Anderson Powerpole Connectors
Anderson Powerpole Connectors – these are just a quick way to connect the DIY extension cord to the battery bank. They also make for a quick disconnect were something to go wrong in the field.
Butt Splice Connectors
Butt Splice Connectors for 12 and 10 gauge wire (fully insulated). I bought mine at Home Depot, but you can also get them on Amazon (click the link). These allow you to connect different types of 12 and 10 AWG wires together (see diagram). Instructions on using these can be found on the electrical basics blog.
Heat Shrink Tubing
Heat Shrink Tubing 3/8 to 3/16 inch for 12 to 4 AWG wires to waterproof the Butt Splices. I bought this, again, at Home Depot but you can get something similar on Amazon. The ones on Amazon say there is a 3:1 shrinkage, versus mine which say 2:1; I don’t know, maybe the Amazon product might be better as it might give a snugger, more waterproof fit. Anyway, once you make your butt splice connection, just slide one of these over the connection and use a hair dryer to make the tubing shrink around the connection. I went further and wrapped the connection in electrical tape after using the shrink tubing, since this extension cord will have to deal with field conditions, which might not always be nice.
Wire Cutter and Stripper
To do all your crimping, cutting and stripping of your wires, you can get a multipurpose tool that does this at Home Depot. Make sure you get one that has stripping options for 10 and 12 gauge wire, and crimping for both insulated and non-insulated crimping of 10 to 12 gauge wire. There are both cheapo versions of this tool and more fancy ones on Amazon also. But if you’re not sure which one to get, I would just go to the local store and play around with them a little.
These pics are from products I bought at Home Depot. You need shrink tubing with an internal diameter big enough to slip over the butt splice terminals, but still small enough that it will shrink tight over the terminals and wires coming out of them. Below are the cards for the other products mentioned that I bought off Amazon.
Extension Cord Wiring Diagram
Solar Input Parts and Wiring Diagram
To make the input wires that are connected to the charge controller, and that connect to the extension cord, it’s just the same process as making the end of the extension cord. Just crimp on the Anderson Powerpole connectors to the ends of the wires and attach the other side of the wires into the charge controller (using a small screw driver). I made these wires rather short to fit inside the ammo box; they are about 12 inches in length.
Battery Input Wiring Parts
In order to make the parallel connections, you will need to buy ring terminals that you will crimp onto both ends of your short, positive and negative 10 AWG connecting wires. The one’s I bought at Home Depot were 12-10 AWG 1/4th inch stud insulated terminals, meaning they have enough room for a 1/4th diameter bolt, which is more than enough for the bolts that come with the batteries. I looked on Amazon for something similar, just in case you’re planning to do one big purchase of everything, and found 12-10 1/4th inch stud RV5.5-6 insulated terminals, which should work. My Home Depot terminals do say “5.5-6” on the sides of the rings, which means 6.4mm or 1/4th inch.
These same terminals will work for the 12 AWG wires that travel to the charge controller, so that you can secure these wires to the battery. However on the positive side, you will want to connect it to the SENSTREE inline fuse wire with a 20A fuse, via a WAGO lever nut connection. WAGO makes it easy to connect wires: just strip the insulation off the end of the wire then lift a lever on the unit, insert the exposed wire into the port that corresponds with that lever, and then close the lever.
Left: 12-10 1/4th inch insulated ring terminal.
Upper right: This is what my parallel connection wires look like, utilizing the 10 AWG wire and the ring terminals crimped onto it. There is also one for the positive (red) side that looks exactly the same.
Lower right: WAGO lever nut
Battery input wiring diagram
Positive (Red) Wiring for Loads – Parts List
To wire the Linkstyle 4 in 1 Charger Socket Panel for the project, you’ll need to crimp on the terminals that come with the panel kit to 12 AWG wiring then plug everything to the back of the panel. The switch has two silver prongs for the positive wiring. The middle prong is what connects to the charge controller and the outer, silver prong is what should connect to the WAGO lever nut to make the parallel connections to the other components in the panel. Don’t get fooled though: the positive prongs on the other components (12V cigarette lighter port, USB port, and volt meter) are all brass, and the negative prongs are all silver; opposite to what the switch is.
The best practice here is to get everything wired to the panel, then decide how long the other ends of the wires should be to connect to the charge controller, when it is in its final position, and the WAGO lever nut. Basically, finalizing the panel wiring will be one of the last steps of the project. But as we get to it, I would leave enough wiring for the panel so that the WAGO rests on the bottom of the ammo can; that way gravity isn’t trying to pull your terminals off the prongs on the components.
Positive (Red) Wiring for Loads – Wiring Diagram
Negative (Black) Wiring for Loads – Parts and Wiring Diagram
About the same deal here as in the positive load wiring, except everything is going in parallel as there’s no switch on the negative side. I finally got to use all of the WAGO’s five ports on this side! Good times.
Amazon Shopping List
If you’re reading over this with the intention of making your own DIY Battery Bank, and want to start researching the prices for these products, I’ll leave the Amazon shopping list below. This links will open new tabs to the products. There are a few ancillary Home Depot (or Lowe’s or other) products that are further needed, which I’ll discuss in the assembly instructions, following the wiring diagrams.
Of course these are just what I used; you’re welcome to do your own picks, but everything I’ve listed, I know is compatible with one another, as I’ve tested this system in the field several times on camps. Check these out, then we’ll move on to the assembly:
- Mighty Max Sealed Lead Acid, AGM battery
- BMK 12V 5A Smart Battery Charger
- Weize 100 Watt Solar Panel
- ALLPOWERS 20A Solar Charger Controller
- Anderson Powerpole Connectors
- BougeRV Solar Connectors Tool Kit
- SENSTREE 12 AWG Gauge ATC/ATO Fuse Holder
- Butt Splice Connectors
- Heat Shrink Tubing
- Wire Cutter, Stripper, Crimper (cheap)
- Wire Cutter, Stripper, Crimper (fancy)
- 12-10 1/4th inch stud RV5.5-6 insulated terminals
- WAGO lever nut
- Linkstyle 4 in 1 Charger Socket Panel
- IRWIN SPEEDBOR Spade Wood Drill Bit 1-1/8″ X 6″
- Flambeau Outdoors 8415AC HD Ammo Can, Portable Ammo Storage
If you’re also making a cheap, compact solar stand for camping, like mine in the pictures at the front of the article, then also get these bungee cords:
And if you’re interested in getting the same fan and lights I use when camping, which work good with the battery, then I’ll leave those links as well:
- Brightech Ambience Pro USB Battery Powered String Lights – 24 Ft Commercial Grade Waterproof String Lights – Outdoor Shatterproof Patio Lights for Backyard, Porch – 1.5W LED Soft White Light
- Quick Products QP-TE1-0126 Boundless Breeze Ultimate RV/Marine Fan – 12 Volt
Assembling the DIY Solar Powered Battery Bank
1. Plywood paneling
Step one will require some carpentry skills, and some 1/8th inch plywood from Lowe’s, or Home Depot (I keep mentioning Home Depot because it’s closer to my house). Open the lid off your Flambeau Outdoors 8451AC HD Ammo Can. You’ll see near the top of the container there is an small inner lip or edge that goes around its perimeter. You need to fashion a piece of plywood to sit on, or nearly on this lip. Measure the width and length of the inner sides of the can, as near to the lip as you can. Transfer your measurements onto your plywood and cut the long side with a circular saw and the short side with a miter saw. Next you will have to measure the angled corners of the ammo can and cut them at 45 degrees with the miter saw. Don’t be afraid to make all your cuts long then, cut down to the correct dimension, little by little as if you were playing golf, each stroke getting closer to the final goal. Once you’ve accomplished this step you should have something like the picture to the right:
Wouldn’t it be nice if that’s all you had to do, but alas there’s very little room in this container, so you’ll need to make two more cuts to this panel, such that the middle section is exposed. This allows the parallel connections on the batteries to peek through the level of the panels, allowing those to sit lower in the can, such that the lid will close. More on making these cuts here in a bit, but the left hand picture shows what’s in store.
2. Add some flooring to the ammo can
Step two also requires a bit of carpentry: You’ve probably noticed by now that the batteries sitting beside each other, like on the picture above, inside the ammo can won’t stay upright. They’ll want to lean one way or the other. To counteract this problem I cut a few spare pieces of 1×2 dimensional lumber and put them in the bottom of the can for the batteries to sit upon.
What might be a good idea, that I didn’t think of at the time, is to cut a few pieces that run the full bottom of the can then dry fit the batteries in place, with hope of coming back later and putting some two sided sticky tape between the battery bottoms and the floor lumber; that will keep the batteries from sliding back and forth on travel. I ended up cutting custom 1×2 pieces that mimic the polygonal shape of the paneling (but are not as lengthy) and putting them in the bottom as stop blocks to keep the batteries from shifting around on my build.
3. Make the parallel wiring for the batteries
Step three: Dry fit the batteries in the middle of the ammo box then cut your red and black 10 AGW to length to create the parallel wires. Strip the ends and crimp on the ring terminals, then temporarily bolt them to the battery terminals as show in the picture above.
Once the parallel wires are in place, measure you paneling so that you can make an end piece for the charge controller to sit on, that doesn’t get in the way of the parallel connection wires you just made. Again see the picture above for what the panel should look like once it’s measured and cut. Use your miter saw to make the cut. Dry fit the charge controller and make sure the lid of the ammo can is able to close properly at this point. There not much wiggle room here.
4. Stencil your 12v RV panel onto your plywood panel and drill the holes for it
Step four: place your Linkstyle panel in your ammo can, near where it will eventually sit, which is on the opposite side as the charge controller. Get an idea of where it can comfortably be on the 1/8″ wood panel with out it, or the eventual final panel shape, being too far on top of the battery such that the parallel connection is in its way. You may have to push the batteries a little bit down to give the Linkstyle panel space. Once you’ve found a good spot, take the Linkstyle panel apart so that only the plate is left (take all four modules off the plate by unscrewing them). Then use it to trace, with a pencil, the holes and outer perimeter onto where it should sit on the plate.
Once you have your tracing, mark the middle of the holes to guide your IRWIN Speedbor Blue Groove Spade Bit (1 and 1/8th inch) to the right place to cut out the holes for the components to penetrate. The bit can be attached to a standard cordless drill like a Dewalt 20V Max Drill).
Using a spade bit through thin plywood is not the best; it will chip away some surface material as it nears the full penetration of the blades to the other side, and it will try to do its own thing once the middle point of the bit has gone through the wood, leaving just the spade blades to do their work. Don’t feel bad if it looks a little ugly, or if you have to sand the inside of the holes to remove material as needed. Indeed if you own a hole saw bit with a 1 and 1/8th inch diameter, that might be less messy. I just used the spade bit because it was cheaper.
Clamp the wood panel down really tight to your work bench, and do the drilling/sanding near the edge of where it hangs over the bench to minimize vibration. Then, go ahead and test your plate against the wood panel to make sure all the holes you drilled line up with the plate, so you can reassemble the components through both the wood panel and plastic plate. Don’t reassemble just yet.
5. Cut your plywood panel down to size so it fits in the ammo can
Step five: Now just cut your panel to length so that its end clears the parallel wires of the batteries, similar to how you did the charge controller side. Test that it fits, then now you can put the Linkstyle plate on the top side and reassemble the components through both it and the wood panel. The individual components just have a large diameter plastic nut on their backs FYI – that’s how they hold to the plate and panel. Don’t worry about the little corner screws for the plate; that’s just low-yielding extra work that may be counter productive. You should now have something resembling the final product:
This picture is just an example of what the paneling should look like by now. By step five, the wiring shouldn’t be in place just yet.
6. Dry fit everything then tape the charge controller to its panel
Step six: Dry fit all your components (batteries, charge controller, panels, plate) and test that the lid will close properly. Once in a good spot, trace the perimeter of the charge controller with a pencil on its panel and affix it to the panel with some two sided tape or thin Velcro strips. Now take the panels out of the ammo can to start the wiring.
7. Wire the battery to the charge controller
Step seven: Wire the battery to the charge controller. Start by crimping ring terminals to your red and black 12 AWG, then affix them to the battery terminals, threading the bolts through both those and the parallel ring terminals. Run the black wire straight to the controller. The red wire end will attach to a WAGO nut, and your inline fuse holder wire will also attach to that nut and then run to the controller’s positive input for the battery. Use the wiring diagram above to help you.
Don’t forget to strip the ends of the wire bare in the places it needs to connect to stuff. You can run the first part of the red wire coming from the battery along the outside side of the battery as shown in the picture. The black one is so close to the controller that it can just come off the battery, run underneath the controller to loop back around to get attached to it so as not to create any stressful bends to the wire. Leave enough length of your wires so that you can still pull the charge controller/panel assembly up away from the ammo can to do the other side’s wiring (or to change out the fuse or fix failed wiring).
8. Wire the 12V RV panel to the solar charge controller
Step eight: Now wire the switch, and other Linkstyle panel components, as shown in the diagram above, leaving enough length on the black and red wires that run to the charge controller to run down the outsides of the batteries (between the battery and inner wall of the ammo case), then loop around in the dead space under the controller and finally to the controller itself.
At this point you can test the Linkstyle panel by switching it on. Once you throw the switch nothing will happen for around 30 seconds or so. The charge controller will start to have a blinking light bulb icon on its display. After this icon turns from blinking to solid then all the components should light up. (See picture above)
9. Make the wires to connect the charge controller to the extension cord
Step nine: make the charge controller’s solar connecting wire with the Anderson Powerpoles as shown in the diagram above. Again I made mine about 12 inches to hide the powerpole end between the battery and inner side of the ammo can when not in use. The powerpoles will clip together to make it easy to connect to the extension cord.
10. Make the extension cord
Step ten: yes, make the extension cord. Cut your red and black 10 AWG nice and long so your battery bank can be in your tent’s vestibule or close by while your solar panel can be at the perimeter of the campsite. Again, use the diagram above and clip the powerpoles together like in step nine, making sure they are color coded correctly to match the red and black wires, as it won’t be obvious which is which when in the field, since the inline fuse wires are all red.
Start off by striping one side of each of the fuse wires, and crimping a respective black or red powerpole connection on the ends. Install the 7.5A fuse on both sides. On the other ends of the fuse wires, again perform your stripping, then feed the shrink tubing onto both wires. Strip you long 10 AWG wires on their ends. Now use the butt splice terminals to connect your inline fuse wires to your long wires, keeping consistent with the red or black powerpole connectors you’ve previously installed on each fuse wire. Once you’ve crimped the butt splice terminals to the wires, feed your shrink tubing over the splice terminal and use a hair dryer to allow it to shrink over it and the surrounding wire material. I would further wrap the edges of the shrink tubing with electrical tape to ensure water or dust can’t migrate into that area.
Now on the other side of the red and black 10 AGW wires, again strip them and install the mc4 connectors making sure your putting the right connector on the right colored wire to work properly with the solar panel. If you buying the Weize 100 Watt Solar Panel I used for the project then the color and connector marriages will be shown on the picture below:
Which is the female and which is the male can get confusing so just put the connector with the round insertion and two clipping prongs on the black wire, and put the one that’s the more square looking fellow that takes the insertion on the red wire.
Use the crimper and plastic wrenches that came with the BougeRV Solar Connectors Tool Kit to install the mc4’s (which also come in the kit as previously explained). Familiarize yourself with the installation process before attempting. The little solar wrench tools also allow you to disconnect the mc4 connections to the solar panel, so you’ll need to keep those with you when in the field.
Finally use a little electrical tape up and down your red and black 10 AWG wires to keep them together as shown in one of the introductory pictures:
Note the dozen and a half individual pieces of electrical tape keeping the red and black wires together. Also note how the Anderson powerpole connections are clipped together.
Thanks for checking out this post, and hope it was useful in planning out your lighting and power for your next camping adventure! Also check out my reviews of other lighting gear I use with the links below:
If you want to see my power bank in action, check out this small video I filmed on my last car + tent camping venture at El Capitan State Beach.
Post Last Updated: 2/21/23