Hacking a cell phone battery to fit an MP3 player

Okay, first let me say the title is a little misleading. We're not so much fitting a cell phone battery into an MP3 player as attaching it as a replacement. With that cleared up, on to the goods.

So, I'm visiting with my friends Josh and James one night. Josh pulls out an old Creative Nomad Jukebox 2 MP3 player. The battery doesn't charge anymore, the bios is somewhat buggy, but it does have 10GBs of space. We looked for a replacement battery, which cost around $50. Frankly, that's more then the MP3 player is worth. But Josh did have an old LG cell phone that was broke, that just happened to have the same voltage specs as the Creative battery. Since we were looking at trying to fit a square peg in a round hole, we took the following approach:

Step 1: Assemble all the parts. We've already dissembled the Nomad Jukebox 2 and the LG cell phone (at least what's left of it).

Step 1 - All the gear

Step 2: Create the power connector. We decided that we were going to use the back plane from the cell phone so that we can clip the battery in. We then cut the LG's circuit board for the power clip section, and soldered on a couple wires.

Step 2 - Create the power connector

Step 3: Create the battery pack. We screwed our power connector back into the cell phone back plane, and ran the wires through where the antenna used to be.

Step 3 - Create the battery pack

Step 4: Test our battery pack. We first had to figure out which wire was positive/negative. After we discovered this (with a little smoke no less), we then soldered on our wires to the MP3 player, and powered it up. Sure enough, it actually worked.

Step 4 - Testing our battery pack

Step 5: Assemble. The final product. We screwed the back plane of the battery pack to the back of the Nomad Jukebox 2, and used some heat shrink wrap around our wires. It came out pretty well.

Step 5 - Assembled - Back Step 5 - Assembled - Side Step 5 - Assembled - Front

Step 6: Rock on. Josh showing off the creation. You can charge the battery through the standard AC charger, and you can keep rocking for hours.

Step 6 - Rock on Josh

This little hack wasn't all that hard to do; the key was that the cell phone battery was 3.7V, just like the original that came with the Nomad 2. Total time spent on this project was around two hours. Most of that time was looking for the soldering iron.