In volume 16 of my favorite little time wasting magazine, Make, there was an article on how to build a ‘USBattery‘.  This involves taking a standard AA battery, gutting it, stuffing a USB flash drive into it, and making it show 1.5v on a multimeter.  It sounded like a neat little project, I had a spare hour, and the right parts laying around to build it.  My optimism was quickly shadowed by frustration, and my spare hour turned into a full day of work.

The first step of the project is probably where I should have known it wasn’t going to be easy.  The author, Andrew Lewis, started by cutting off just the tip of an alkaline battery.  He used a primitive hacksaw to accomplish this goal.  I decide that my Dremel could do it quicker, easier, and cleaner than a hacksaw.  I slowly started cutting through the discharged battery.  As I broke through the thin metal skin and my small rotary disc made contact with the goo inside, the speed of the Dremel tool picked up the black sludge and sent it flying in all directions.  Thankfully I was wearing goggles, as that was the only part of my face that was spared of the not-so-pleasant feeling of the battery acid.  Sometimes primitive tools work better than their modern equivalent.

Once the top of the battery was removed, you are left with the top of the battery, which has a rod sticking out of it, and and the bottom of the battery which is filled with carbon sludge.  The next step was probably the hardest step.  I chopped off the little rod, and then went to work on the plastic that holds the conductive ‘plate’ of the negative end of the battery.  You want to remove this, so you are left with a just the outside ring.  You will eventually stick a little battery in it’s place, which is how you get the 1.5v.  The only problem with this part is that the little plastic piece did not want to come lose.  I drilled, cut, and pulled at the plastic with my pliers.  After about what seemed like an hour of frustration, the plastic piece came lose.

Cleaning out the inside of the battery was actually pretty easy.  Using the right sized drill bit, I just slowly drilled away at the carbon until it was completely gone (carbon is conductive and could short out your USBattery).  After doing a final rinse in some soapy water, I had a nice clean shell of a AA battery.

I found an old cheap 1GB USB flash drive laying around, and pryed off the plastic casing.  The USB drive was too big to fit into the AA batttery, so I once again pulled out the Dremel tool.  I ground away as much of the PCB as I could without hitting any of the traces.  With a bit of a push, the USB drive fit snugly into the AA battery.  Before I could glue it into place, I had to remove the standard USB plug, and replace it with a USB mini plug.  With a little slack in the thin wires coming off of the USB mini plug to the flash drive, I was able to fit them both (barely) into the AA battery.

I then went to work on the cap of the USBattery.  The first step was to solder a little button battery to the top ring of the AA.  This sounds a lot easier than it really is.  You only have a tiny bit of the battery to solder to the metal ring, and if you apply too much solder to the battery, it will short out the battery.  After many failed attempts, and some dumb luck, my solder bound the battery and the ring together without any shorts (yay!).

All that was left was to add the tiny magnet into the case to hold the top into place, and also act as the conductor between the negative side of the battery and the AA casing.  This, like every other step in the process, was harder than it looked.  You have to line up the magnet so the right polarity is facing the bottom of the battery.  Unfortunately, the magnet did not want to face this way, and insisted on facing the opposite way.  So, I held it into place with a tiny set of pliers, and quickly covered it in 1 min epoxy.

I did some quick tests to make sure the flash drive was still in working order, and the battery would read 1.5v off of a multimeter (almost done).  The last step was to make a nice label.  I decided to make my label look as close to a Duracell battery as possible (mainly because it is pretty simple to duplicate).  I started up Photoshop, and went to work.  Using the Make template as a size guide, I took the actually Duracell logo, and cut and pasted the text to spell Datacell (clever).  I printed it out on some sticker paper I picked up at Office Depot (expensive!) and it fit perfectly.  In one final stroke of genius, I took some clear heat shrink tubing and covered the label to protect it, and give it a nice shine.

Overall, a frusterating project, with a great ending product.  Even though I never use the little flash drive, it is fun to show off to friends.  See some final product pictures below.