This instructable is a field charger/ power supply to run low draw electronic devices such as phones radios and cameras in the field without having to go find an outlet or 12v receptacle. this instructable is intended for someone with a reasonable working knowledge of electricity. if you are not confident in your wiring ability do not attempt this instructable as you could cause serious damage to your equipment

Step 1:

Some example devices that can be charged are from left to right.
~ Inverter
~ Radios
~ iPods
~ Phones
~ Digital cameras
~ Rechargeable packs

Step 2: Tools

these are some of the basic tools required for the project, depending on your components you may need more tools
~ Soldering Iron
     --  you can use wire nuts for this project but i prefer to solder all my connections especially in an
         environment where the wires will move
~ Hot glue gun
     -- used to hold wires down and such in place for a nice clean look
~ Multimeter
     -- to check all of our connections
~ Wire strippers
     -- to strip and cut wire and crimp on terminals
~ Tape
     -- to tape over the wire connections to prevent short circuits
~ MultiTool
    -- to cut wire, bend tabs, cut tape and just about anything else

Step 3: Parts

Listed below are some of the basic parts that are used in this instructable, your build may require fewer or more parts depending on the requirements of your box. the upper limit of current that can be drawn from this box is 5A, using 6 batteries that draw can be sustained for three hours.

~ 12v receptacles
      -- since all of the devices that i will power from this box will draw very little current i decided to add
         another receptacle so that i can charge multiple devices at the same time
~ Misc adaptors
      -- these pictured are just a sample and the ones you will need will depend on your device, pictured
          are a 120V ac to usb a 12v to mini usb cable
~ Epoxy packs (optional)
      -- a more permanent way to attach the batteries to the box to keep them from sliding around in transit
~ Switches
      -- to turn off the box when not in use and so we can leave all of our chargers plugged in without having
         to worry about the vampire load
~ Test leads
      -- also known as alligator leads, these are used in testing and to connect the charger output to
          virtually any battery
~ Solder
      -- for soldering our wire connections
~ Marker (optional)
      -- To mark where we will place components
~ Batteries
      -- to charge and to be charged
~ LED tubes
      -- to make the box easier to find at night and to provide a little working light
~ Terminals
      -- to make the connections to the batteries easier
~ Solar Panel
      -- While this box can be used for an extended period of time without recharging it is capable of being
         charged by any dc source from 10v to 15v
~ Charger
     -- the reason that i chose to use the triton jr for this project is that it is more efficent than most other
         computerised chargers and it has the ability to charge almost any type of battery. also it has a
         nice small formfactor and was redialy avaliable

Step 4: Accesories

Some accessories that you may want to consider are voltage meters to see how much charge your batteries hold. Binding posts on the outside to make hooking up solar panels and other devices that connect with alligator clips easier. A 120v to 12v adaptor so that you can just plug it into a wall outlet to charge, I did not add this in my instructable because the charger that I used can already do this without the need for any additional parts. A low voltage cutoff if you plan on drawing a lot of power, my charger provides this so again I didn’t add it.

Step 5: Plan

this is the basic plan of how everything will be connected. if you are going to add any accesories or other features such as a voltmeter or usb plug this is where you want to add them to your plan.

Step 6: Layout

The next step is to find the optimum layout for your batteries, receptacles, charger and any other accessories you will use. I placed my battery bank in the center for a nice clean look and my led tubes on the side so that I can see all my connections when using it at night, this makes attaching devices much easier in the dark

Step 7: Testing

Arguably the most important step in any project is testing, for this project I tested everything. it is still easy to make changes at this point and much better to find out that you wired something wrong or that  part is bad now then to find out when you plug in an expensive radio or camera. Because I had not used these batteries in a long time and they are slightly used, i tested all of them to make sure I did'nt have any bad ones. I also tested the voltage using the chargers load feature to get a better idea of how healthy they are. some people have asked why i test so much since i havent even put it togather yet. the reason is that i would rather find out a used part is bad before i spend my time and money on a project only to later find out that it wont work.

Step 8: Testing the Layout

Once we have tested all of our components, it’s time to assemble everything and test it again. it is a little hard to see but the batteries are connected in rows positive to negative to make three sets of 12 volt assemblies, then these are all connected so that we have a 12 volt source with a larger capacity. I also tested the wiring for the LED tubes and the charger again. I also did a test run and charged an 7.2v 6 cell battery

Step 9: Assembly~1

The first step in the assembly process is to cut your connecting wires, the length of these will depend on the geometry of your cells, mine where very close so I used a four inch length of wire. Next I crimped on ends so that they could be easily connected to my batteries. The ends are kind of shaped like a “B” and will fit over the terminals of my batteries. The size of connector will depend on the size of you battery terminals.

Step 10: Assembly~2

The next step is to wire up the ends of the cells, these will tie all the positives together and the negatives. I prefer to solder but you can use wire nuts if you are not comfortable with soldering. I will not explain how to solder as there are some fantastic instructables on the site already. I soldered a wire for each battery and then a main feed wire to run to all my devices. Next I crimped on another connector on the end of each wire so that they can be easily attached to the batteries

Step 11: Assembly~3

The third step is to wire it all together the same way that you tested it, I started by connecting the middle ones positive to negative then moved to the outside ones positive to positive

Step 12: Testing~2

Once you have it all wired we need to check our wiring again just to make sure that we wired it correctly and. This is very important as these batteries can easily start a fire if short circuited. i then used test leads to check that everything was working before soldering the led tubes and the 12v plug

Step 13: Testing~3 & Operation

The last and final test is to plug in your devices and check that they charge or operate, in the example I demonstrated how versatile the system is at taking almost any charger and still be able to charge the device. I also checked the charging feature of this box by connecting it to various input sources to check the charging operation, to do this I plugged the charger into the main feed lines and then to the my external power source. Then I set the battery type on the charger to Pb for lead acid and the voltage to 12, then press and hold start this starts a battery test cycle then the charging cycle, the screen will read out information regarding to the input voltage and current and output. once it was working properly I let it charge for a little while since my batteries where not fully charged. This charging process will depend on your charger but the way that you charge all the batteries will be the same except for your charger settings.

Step 14: Other Thoughts~conclusion

After building this project and using it I realized that I didn’t need 6 batteries and 4 would be plenty for all of my applications so I set out for a smaller container. This old cooler holds 4 batteries perfectly and has a convenient carrying handle so it can be carried in one hand and is much less awkward than the old box. Due to the smaller size I can’t fit the led tubes in it but the white inside reflects the extremely bright charger backlight and makes it quite easy to find in the dark as long as the lid is slightly open.
Great ! Be careful with playing with Lipo batteries as a Lipo fire is dangerous and Lipo batteries can explode if over charged. charge them in a Lipo safe bag, and fire proof box recommend :)
Nice idea, lots of energy.<br />But instead of using an inverter to go from 12v to 120v AC and thenusing a transformer to go back to 5v DC, why not get a 5V regulator,whack a heatsink on it and then wire the output to a couple of USB portsthen you can plug your iPod and phone into the USB port. Would be alotmore efficient and a voltage regulator is cheaper than an inverter.
yes and i explained that in the instructable, while that would be moreefficient to not step it up to step it back down, it is just an exampleof how it can be used <br />
This is a very nice Instructable and very useful.&nbsp;<br />I have that same battery and that same charger and this is exzactly what I do for charging my airplane battery!

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