Ammo Can Solar Power Supply

74,282

531

74

About: Ordinary guy with no special skills, just trying to change the world one backyard invention at a time. See more at: http://300mpg.org/ On Twitter - @300MPGBen and at Ecoprojecteer.net

For this project, I'd like to show you how to build a portable solar power supply in an ammo can!

This is a great project to learn about the basics of electronics, batteries, and renewable energy. The finished project can charge a phone or tablet, light up a camp-site, and provide for whatever other small electric needs you have.

This is ideal for emergencies, camping, or any off-the-grid getaway.

Whether you call it a solar generator, a camping go-box, or anything else, you'll love having an Ammo Can Solar Power Supply!

For a quick video overview of the project, please see:
https://www.youtube.com/watch?v=2NIzIR_Lbkw


For the full-length, step-by-step, instructional video, please watch at:
https://www.youtube.com/watch?v=g2cLMk3nD3Y

Step 1: Materials and Tools

This project is essentially a battery inside a sturdy box with a handle. I choose an 50 caliber plastic ammo can, as I've found them to be very handy as tool boxes and storage containers. Ammo cans stack nicely, carry easily, and have a weathertight gasket seal.

In the past, many of my projects made use of "Unique Parts" (such as bulletproof glass pulled out of a dumpster!) In this case, I wanted to made use of as many "off-the-shelf" parts as possible. For one thing, it makes it very easy for OTHER people to also make their version of the same project.

In this case, I happened to purchase most of the components from a major online retailer. If you'd like to do the same, I've provided links to the items I used. I've also added approximate prices for those materials at the time of this writing.

For this project, we will need:

Ammo Can, 50 cal.
I really like the MTM brand. Nice boxes, made in the U.S.A. Available in multiple colors. Black and green are both classic, but you might want high visibility orange if you intend to use this as emergency equipment. http://amzn.to/2FI8lFw

Sealed Lead Acid Battery, 15AH capacity. I specifically chose a particular physical size, as it fits perfectly inside the MTM Ammo can. It's also a relatively small battery, which keeps the project weight to right around only ten pounds. I used a "Mighty Max" brand battery. http://amzn.to/2FBmroN

20A Solar Charge Controller I found a nice one which has some good safety features, low-voltage disconnect, and also includes a pair of USB ports built in. http://amzn.to/2FAJyjo

Four In One Socket Panel This is a device typically sold for trucks to add a 12V cigarette lighter outlet, USB ports, a voltmeter, and a switch to turn it all on and off. They are available in several shapes sizes and colors. http://amzn.to/2FHxCj4

Banana Jacks These are used as universal electrical inputs and outputs on the project. This project uses two pairs, but since I knew I'm be using more in the future, I bought a box of 10. http://amzn.to/2FMDK9I

12 AWG stranded wire in both black and red (From local hardware store)

Crimp on electrical terminals, spade and 1/4" ring terminal

Silicone adhesive or hot glue

Industrial type hook and loop fastener (Velcro) http://amzn.to/2FMDK9I

Wire Nuts or Wago (Brand) Lever Lock Nuts. http://amzn.to/2FBj15k

Fuse Holder and Fuse. http://amzn.to/2FMLmJp

6-32 and 8-32 nuts, bolts, and washers

The project also features "accessory items" that simply plug in to the Solar Ammo Can to make it as useful as possible. To start with, we will want to be able to charge the battery.

Solar Panel - I already happened to own a solar panel perfect for this project, a 15 watt PV Solar panel. Any 12V nominal solar panel of about 10 to 20 watts is perfect for this project. Here's one which looks affordable, and it about the right size and style for the project. http://amzn.to/2DlkpHw

DC Power Adapter (Wall Charger) Any DC wall power adapter of higher than 12V (13.2, 14.4, 18) and one amp will work fine. I already had a 18V 1.3A power adapter handy. Here's a similar adapter. http://amzn.to/2FMUrBS

The other items I packed into the ammo can were for lighting and AC power.

USB Gooseneck Light These small USB lights work great. They are very simple and durable. Fantastic for camping. http://amzn.to/2GhvQTy

100 Watt AC Power Inverter. This device converts DC power to AC power so that you can run typical household devices from a battery. A 100 watt version is very compact and inexpensive. I already had one, which I used for this project. Here is a similar version. http://amzn.to/2FBjGDQ


For this project, we'll need some pretty straight-forward shop and electric tools:
Tape measure / Ruler
Pencil
Drill and drill bits (alternatively, access to a laser cutter)
Wire strippers
Wire crimper
Screw driver
Nut-drivers or sockets to fit 6-32 and 8-32 hardware
Optional: Access to a CNC Vinyl-Cutter to make a graphic.

Now that we have our tools and materials, let's get to work!

Step 2: Laying Out Components

I set the battery inside the ammo can, and arranged it approximately in the middle. This helps with balance, so the finished project doesn't feel off-center when you pick it up.

There is empty space on both sides of the battery. On the one side, that space will be taken up by the wiring from the back of the various electrical connections. The other side will be reserved as storage space so that we can include lights and the power inverter in the project.

All the switches, outlets, and connections will be INSIDE the ammo can. The ammo can is already designed to be weather-proof and includes an o-ring or gasket. Some people have designed similar projects where they drill holes through the sides and top of the ammo can. To me, it seems a shame to put holes into something that's already designed to be weather-proof!

Instead, we will design an internal faceplate which will go over the top of the battery and mount all the components together.

The area inside the ammo can, covering the battery and the one open side, comes to approximately 6 inches by 8 inches. I drew that rectangle out onto a piece of paper, and then started to arrange my main components. I wanted to include the Solar Charge Controller, the 4-in-1 Socket Panel, and two pairs of banana jacks on this panel. I arranged the components so that the Solar Charge Controller would be directly over the top of the battery, and the other components were to the side of it.
With the components in place, I could trace them and their mounting holes.

After I did that, I did the same on a piece of cardboard. Cardboard is nice because it's inexpensive and quick and easy to work with. It makes a good temporary mock-up. (I call this CAD - Cardboard Aided Design.)
I cut the holes in the cardboard and temporarily installed the components to make sure that they would lay out well and sit inside the box over the battery as I would expect.

On a typical home workshop project, this is the point where I would lay my paper template over a piece of wood or plastic and drill the holes and cut out the shape. In this case, I realized that other people might want to duplicate my project, and that having a DIGITAL version of my layout could be useful.

I took the individual components and placed them in a computer scanner. I scanned in the components, and then brought them in to Vector editing software. (I happened to use Adobe Illustrator, but any vector software will work.)
Inside the vector software, I could draw the shape of my faceplate and precisely locate the holes that would be needed to mount the components.

Step 3: Cutting the Panel

If you just have access to common shop tools, lay your paper template over a thin piece of wood, metal, or plastic and tape or glue it down in place. (Thin plastic cutting boards are commonly used as source materials for projects like this.)

Next, drill holes as needed for mounting down the components. (I mostly used 3/16ths inch holes)
The holes for the cigarette plug style connections in the 4-in-1 Socket will require a 1&1/8th inch spade drill bit, or better yet, the same size Forstner bit.

On the other hand, if you have access to a laser-cutter, load the vector file you created into the laser-cutter computer. Make sure to adjust settings as needed for whichever material you are using. It's always a good idea to make a test cut on some inexpensive disposable material.

I added some text I wanted engraved with the laser-cutter, but forgot to set it to a lower power than the cut lines. Instead of engraving, the lettering was cut right through! Oops! Good thing that was just on a test piece of cardboard. After correcting the power setting, we cut a faceplate panel from a piece of 1/8th inch thick plywood.

It looked very nice, with clean cut lines, and easy to read engraving.

Included in this step is an Adobe Illustrator file and a DXF file, if you would like to laser-cut this same component.

A big thank you to our friends at Brown Dog Gadgets for their assistance with laser-cutting!

Step 4: Assembly

Assembly onto the faceplate is relatively straight forward.

Use the 8-32 hardware to mount the 4-in-1 Panel. Next, push the individual components (switch, USB plugs, etc) through the large holes and then secure them by rotating the rings on the back.

The banana jacks are pushed into the plate and then a backer goes on, which is held in place by washers and a nut.

I recommend NOT mounting down the the Solar Charge Controller right away. Because the wiring has to come up through the faceplate to get to the Solar Charge Controller, it's difficult to get the wires to the screw down terminals. It's easier to wire the Solar Charge Controller, and THEN mount it down to the faceplate.

At this point, you now have the components assembled to the faceplate. Flip the faceplate over and wire up the project.

Step 5: Wiring

The Solar Charge Controller is rated for up to 20 amps of current. As such, we want to use wire and connectors rated for 20A as well. That means using 12 AWG wire. Crimp on terminals that work with 12 gauge are usually color-coded yellow.

BATTERY CONNECTION
Our 15AH lead-acid battery has 1/4" spade terminals on it, so we will crimp on a female spade terminal onto the end of the fuse holder. The other end of the fuse holder is stripped and inserted in to the Battery + connection on the Solar Charge Controller. We will use a black wire with a female spade to connect the battery's negative terminal to the screw down terminal on the Solar Charge Controller marked Battery -.

SOLAR CONNECTION
For the banana jack marked "Solar IN" we will crimp on a ring terminal onto the end of a wire. Cut that wire to length to reach the Solar Charge Controller. A red wire will go from the red banana jack to the SCC (Solar Charge Controller) screw down terminal marked SOLAR IN +. Likewise, a black wire with a ring terminal to the SOLAR IN -.

LOADS CONNECTION
Wiring the loads is a little more complicated. Besides the 4-in-1 Socket panel, we also have the additional banana jack as a secondary 12V output. Each electrical device needs to connect their positive with a red wire to the LOAD + on the SCC and every negative has to go to the LOAD -.
Since we have multiple connections, but only one screw each on the Solar Charge Controller, we will need to combine wires by twisting them together with a wire nut. Alternatively, I recently found a connector made by a company called WAGO. They have a Lever-Lock Nut. This device allows multiple wires to combine together, sort of like a mini bus bar. Each conductor locks in place by a spring-loaded lever. These lever lock nuts are rated for up to 20 amps, are reusable, and make it easy to add or remove wires.

I crimped a female spade connector onto a black wire for all the load negatives. The opposite ends were stripped and then combined together in a Wago nut. That nut also connected to the LOAD - on the charge controller.

The positive side was slightly more complicated. I wanted the banana jack always on, but the items in the 4-in-1 Socket Panel to be switched on and off. To accomplish that, I ran the positve red wire from the solar charge controller LOAD + to a ring terminal on the positive of the banana jack AND to the middle conductor on the switch of the 4-in-1.
Next, I made red wires with spade terminals to connect to the positives of the remaining connector (switched output) on the switch and the other items of the 4-in-1 Socket Panel.
That provides power always on to the Banana Jack, and power to the 4-in-1 only when the switch is on.

Once everything is wired, the Battery + and - wires can be plugged into the battery, and the system can be tested out.

Step 6: Battery and Panel Mounting

One of the goals of the project was to not drill or cut holes in the ammo can.

So, then how do we mount the components inside the ammo can? What keeps them from shaking loose and sliding around?

The battery really already fit very snug. To secure it, I placed a few dabs of silicon glue (caulk) in both the bottom and the sides of the ammo can. I then placed the battery back down in the ammo can and let the glue dry.

The faceplate with all the electrical components mounts right over the top of the battery. I held it in place with industrial strength Velcro brand hook and loop fastener. To allow for the space taken up by the battery terminals on the top of the battery, I added a small wood spacer, glued that directly to the top of the battery, and velcro'd the faceplate on there.

Using Velcro securely holds the faceplate, while still allowing for easy removal to access the wiring. You would need to do this to replace the main fuse, for example. Also, if the project is going to be put in storage for a while, you would want to completely disconnect the battery. Always store batteries charged and NEVER with anything attached, including a battery charger which is not actively charging.

As a finishing touch, I created a graphic on my vinyl-cutter using a stencil font and applied it to the ammo can.

(I added two versions of the "SOLAR AMMO CAN" cutter file. One is specific to the Silhouette Cameo format, and has multiple stickers. The other is a generic .DXF file, which you should be able to import into any CNC cutter program. I've found that sometimes with that format, the objects aren't the right size on import. If that's an issue group all the elements and proportionally scale them so that the outside rectangular box is 8 inches wide.)

Step 7: Solar Charging

This system is designed to be charged by a solar panel
What size solar panel do we need, and how long will it take to charge?

A "12V" solar panel is actually one which is designed to charge a 12V battery. To do so, it needs to produce voltage HIGHER than that of the battery. Common solar panels used to charge 12V batteries are often about 18V

Every solar panel will have a sticker on the back listing its maximum voltage and maximum current. The one I have is rated at about 18 volts and 1 amp max current.

The battery is rated at 15AH (am-hours.) If it was completely depleted and I had a 1 amp solar panel, it would take 15 hours of full sunlight to recharge. However, we never want to completely drain a battery. It's pretty common practice to discharge a 12V lead-acid battery to no more than HALF.
In that case, we would need to replace 7 or 8 AH and if we were using a solar panel producing 1A, it would take 7 or 8 hours. I'm intending to primarily use the Solar Ammo Can while out camping during the summer - the time of year when the days are extra long, and the battery would get plenty of charge.

For this project, a solar panel with a 1 amp output will be sufficient, and a 2 amp output would be even better.
Here's a video review of a small solar panel appropriate for this project: https://tinyurl.com/ybp3qyz3

So, how do we charge the battery at night or in cloudy weather?
You will notice that there is NO AC input on the project. To charge from AC grid power, we will still use the SOLAR IN connection.
A DC power supply converts the AC to DC and the Solar Charge Controller will properly control the charging of the battery. The DC Power Supply (wall wort!) simply needs to provide voltage higher than that of the battery. There are some power supplies which specifically output 13.2V or 14.4 volts specifically for 12V charging. Anything in that range on up to the maximum the Solar Charge Controller is rated for will work fine. (A laptop power supply would work great!)
I'm using an 18V 1.3A DC power supply for grid-charging the Solar Ammo Can.

Step 8: Using the Solar Ammo Can

In use, the Solar Ammo Can is super-handy!

I open the lid and have the small gooseneck LED light ready in the USB.
The 12V DC LED bulb is extremely bright. The cord on it is long enough to throw the bulb up over a tree-branch. The hanging bulb will light up a whole camp site!

The AC Power Inverter works great too. I don't need it that often, but it's nice to have. It works well with long strings of LED lights which are designed to work on AC - they are low current, but still require AC, so they are a nice match with a small inverter. I have a string of AC LED lights on my back porch. Each bulb is only one watt, and there's a dozen bulbs in the string. Total power is 12 watts. The ammo can can power my back porch in a blackout. Alternatively, this style of lights is great for lighting up an area at a camp-ground, or even for interior lighting in a blackout!

The USB jacks work great for charging phones and tablets. Keep in mind that some USB jacks are only good for 1 amp or less. All the USB connections on this project are at least 2.1A - so tablets and other power hungry devices can charge at full speed!

Having all the accessories pack INSIDE the box works really well. If they didn't I'm sure they'd all get lost!
The only thing which DOESN'T fit inside the ammo can is the solar panel itself. I have found a folding solar panel which could fit inside a 50 cal. ammo can and I have some ideas for a future version where even the solar panel fits inside!

Lastly, there's more than one way to make a project like this. People have used tool-boxes, built custom wood cases, used very large batteries, added wheels, and have done almost every other variation you can think of.

For me, I wanted something portable, which looked nice, and could power communications and lighting. I think it's accomplished that goal just fine!

Now, it's time for YOU to make one! Show us what you come up with!

Step 9: Disconnecting When Not in Use

One thing that can be somewhat strange about battery chargers is that they can DRAIN the battery!

Many battery chargers, if left connected to the battery, but NOT powered up, can drain a battery. That can include a solar charge controller like the one used in this project. For example, the charge controller has a display. Simply powering display that takes energy from the battery.

When NOT using the Solar Ammo Can, you can simply pull the main 12+ positive connection from the battery. Alternatively, you can pull the 12V fuse.

If you would prefer, you can also wire the project slightly different so that the switch in the Quad-Socket acts as a disconnect switch between the battery and the solar charge controller. Remember to flip the switch to ON when trying to CHARGE the battery as well!
Please see the image for the alternate wiring diagram.

Share

    Recommendations

    • Organization Contest

      Organization Contest
    • Epilog X Contest

      Epilog X Contest
    • Pocket Sized Contest

      Pocket Sized Contest

    74 Discussions

    0
    None
    NateC46

    12 days ago

    Would it be possible to put two batteries in the box, one on each side with plugs in the middle. How would I wire the batteries to work together?
    Thanks!

    1 reply
    0
    None
    bennelsonNateC46

    Reply 11 days ago

    Yes, you could add a second battery. It would double your usable power, and also take up the "storage space" designed in the project.
    You would wire up the batteries in Parallel. Connect Positive to Positive and Negative to Negative.
    Parallel connections keep the voltage the same, but allow for twice as much current, or in the case of batteries, twice as much capacity as rated in AH.
    Do a web search for "Parallel Battery Connections" for a deeper understanding.
    https://en.wikipedia.org/wiki/Series_and_parallel_...
    https://www.batterystuff.com/kb/articles/battery-articles/battery-bank-tutorial.html

    2
    None
    heIIo

    2 months ago

    A slight variation using Anderson Power Pole connectors and a steel ammo can.

    36161171_1859598867431882_5711183455631441920_n.jpg
    1 reply
    0
    None
    bennelsonheIIo

    Reply 19 days ago

    Well done! Please use the "I Made It!" feature so that everyone can see this right away at the end of the Instructable!

    0
    None
    phishinphool

    Question 20 days ago on Step 9

    What was the total cost for parts assuming everything is bought where you suggested?

    1 answer
    0
    None
    bennelsonphishinphool

    Answer 19 days ago

    All the components together should cost about $80-$100.
    The specs of this project happen to be very similar to a commercially made one costing $200. Of course that one, you don't get the fun of building yourself, learning how it all works, or being able to fix it! https://amzn.to/2EeZyIi

    0
    None
    jwfinnell

    2 months ago

    I like the ammo can form factor very much but I wonder if a lithium ion battery as found in small jump starters could be used instead of a SLAB? It would dramatically reduce the weight and they can be found for 60-70$ vs 35 for the SLAB.

    2 replies
    0
    None
    bennelsonjwfinnell

    Reply 19 days ago

    You certainly could use a lithium battery. It adds to the cost and complexity, and I wanted this to be a beginner project that ANYONE could tackle. The most important part of using lithium is to make sure you have an appropriate Battery Management System (BMS)

    0
    None
    jwfinnelljwfinnell

    Reply 2 months ago

    They also have their own charge controller built into the device.

    0
    None
    Henmarsh

    20 days ago

    Thanks for a terrific, comprehensive and well presented instructable. I need to use a CPAP machine (for sleep apnoea) at night - a bit inconvenient when you want to camp out for a few days! I built this battery pack last Summer incorporating a battery, charge controller and an inverter all powered from a 100 watt panel.

    Ammo cans aren't easy to come by here in the UK so I used a plastic tool box instead. I don't have access to a laser cutter so envy the elegance of your panel!

    On the top of the box there are switches operating a battery condition meter and an led strip inside the box. I use an automotive battery isolation switch to disconnect the battery and there's a meter showing battery discharge rate and other data. I *love* meters!

    The unit works well and runs the CPAP machine for a couple of nights without recharging. It's also very handy to have about when I need to run lights, charge phones and such.

    IMG_20190225_204649.jpgIMG_20190225_204747.jpgIMG_20190225_204723.jpgIMG_20190225_204704.jpg
    1 reply
    0
    None
    SHOE0007

    20 days ago

    I admire the skill in doing this-- Keep up the good work! How efficient is it when you get full to partal sun light?

    0
    None
    kd4gcf

    2 months ago

    I would want to configure it with one more switch to be able to charge the battery without having to have the panel on. I wonder why you choose to have more USB charging ports or the voltmeter when they are integrated in the charge controller.. I will look at specs to see it either provide a AMP setting. Otherwise an AMP meter would be nice.

    2 replies
    0
    None
    bennelsonkd4gcf

    Reply 2 months ago

    The joy of a project like this is that you can configure it any way you like!
    I like the "Quad" Port as it has a solid 12V "cigarette lighter" jack and switch. You can also read the volt-meter there at night, in the dark, whereas the voltmeter built into the the charger controller isn't backlit. (I mostly built this for going camping, and using it at night!) I wanted at least a dedicated cigarette lighter jack, the quad had it, and the rest was a bonus.
    You might NOT want to have a switch to disconnect the Solar Charge Controller, as the POINT of the device is to help properly charge your battery. You are unlikely to overcharge with a small panel, but I don't see any advantage to disconnecting the controller.
    On the other hand, if you will NOT be using the device for a while, unplug the battery.
    If you prefer, it could also be wired up to use the switch on the quad as a "Master" disconnect between the battery and everything else. Here's a video on how to do that: https://www.youtube.com/watch?v=4YKRa9m4N7M

    0
    None
    kd4gcfbennelson

    Reply 2 months ago

    Thank you for your response. I did not realize the controller was not backlit so your point is taken. I did not present my switch idea well I think. I was just saying it would be good (for Me ) to disconnect the "load" if only recharging battery using what ever source. Having the current only flowing from charging source into controller and then in battery. Maybe your switcg does this but when I watched the video it did not appear that way. I will be watching your video again. Also I enjoyed your electric bike write up. Sad my trip is 20 miles one way and I am 300 lb dressed. 73

    0
    None
    treymartin82

    Question 1 year ago

    Could this be done with lithium ion batteries? I know that they are lighter. Complete beginner here so sorry if this sounds dumb.

    2 answers
    1
    None
    bgreen3treymartin82

    Answer 2 months ago

    Yes, it certainly could. The problem is that lithium charge controllers are quite a bit more complicated than lead acid controllers. You need additional leads between each of the cells to make sure they stay "balanced"

    1
    None
    JamesA41treymartin82

    Answer 1 year ago

    Yes, however, you need to make sure you use a charge controller for lithium ion batteries or any battery chemistry you want to use. This will assure optimal life cycle and use of your batteries. Keep in mind also, with lithium ion batteries over protection fault circuitry is needed unless maybe INR or LiFePO4 style.

    0
    None
    tem494

    Question 2 months ago on Step 3

    I enjoyed your project being a “ham radio operator I am always on the lookout for portable power projects.
    I was intrigued by your lasercutting of the panel. Could you tell me a little more about the power needed to cut the plywood as well as brand you are using. Most I see advertised are listed as engravers. Any help you can shed on this would be appreciated.
    Again nice project well thought out and presented

    1 answer
    0
    None
    bennelsontem494

    Reply 2 months ago

    The laser cutting was done at a friend's shop. I don't recall the power of the cutter off-hand. The wood is essentially 1/8th" thick. I designed the layout and made the file and just had the friend cut it for me. Our local makerspace has 30, 50, and 60 watt laser cutters available for use.
    Even lower power lasers can often still cut, but need multiple passes.
    I believe the following laser cutter is very similar to the one I actually used for the cutting: https://wiki.milwaukeemakerspace.org/equipment/lasercutter3