I used to have one of these battery packs for the Game Boy when I was younger. It had a handy clip on the back so that you could hook it onto your backpack, or (if you were style-unconscious) you could hook it to your hip and totally rock it like a fanny pack full of Ni-Cd batteries. The thing would last forever on a single charge. Of course, the Game Boy itself could last for a while with four AA batteries.
The folks over at the Victory Pointe brought one in as part of a "Thanks" for helping them fix up some equipment. I was more than gracious for the rest of the stuff, but I became especially interested when I saw this battery in the bottom of the box. It was like seeing an old friend.
Well, an old friend that I would soon operate on with a set of rusty screwdrivers.
The original batteries in the pack were not too impressive. Actually, there were four AA cells in a block, surrounded by an orangish-yellow plastic wrapper. After getting it unstuck from the inside of the Game Boy, I got to work by finding an RC car battery pack that had been sitting on my shelf for a while. I carefully cut its wrapper and exposed its cells. Each of these were significantly larger in both capacity and size. When I tried to close the shell back into place, it was about 1 centimeter off from having enough clearance. I could have just Dremeled more of the plastic out, but I didn't want to risk ruining the case and the esthetics. So instead, I took three batteries, lined them up in a row, then stacked the fourth cell onto the top of the others. In this config, the valley between two batteries snuggled the top battery in such a way that it gave me the clearance necessary for closing things up. It's like battery Tetris!
Soldering to battery cells always makes me a bit nervous, but things worked all right as they usually do. My usual go-to is using a piece of solder wick as a conductor between the cells. I will rough up the surface of the metal with a small emory board and stick 'em together. In this case though, I just roughed it up and soldered the wire directly to the cell. There is a bit of glue for insulation and stability purposes over the top of the solder as well.
After getting the batteries to fit, I took it back apart and I used high-temp hot glue to hold everything in place as well. I love hot glue. You can pretty much use the stuff anywhere!
The battery had a minimal charge when I first plugged it in. After a few hours though, it made it to about 5.1v, according to my multimeter. I am curious to see how long it lasts with these cells. Combined they are 1600mAh, which is nearly three times larger than the 600mAh cells that were in there in the first place. Because they are powering an old-school game boy, I estimate that this will be played by cockroaches after the apocalypse. Read the full post... about Image Gallery - Cannot stop the Battery!