We’ve been doing a bunch of battery testing lately, and I have some very promising results to share with you guys. I have 2 main options to recommend, but if you want details of other tests, you can head over to this forum post to get them (http://forum.freeplaytech.com/thread-4418.html).
Our test setup was a Game Pie Advance (GPA) v1 PCB modified to use the Adafruit PowerBoost 1000c circuit. This setup charges the batteries and boosts them up to 5v to power the Pi. We boot up the GPA, select a GBA ROM, and let it sit (full volume) in attract mode until the GPA dies. I think it’s actually fairly real-world, as it’s running the GBA emulator the entire time.
The first recommendation is the Sanyo UR14500 cells. The best part of these batteries is that they will fit right into your Game Pie Advance’s AA compartment. We would be using the cells in parallel, so you’ll have to do a little tweak to get them to work, but we have that planned out already. When the boards are ready, we’ll show you how to do that. You can get cheap 14500 cells (which we had been using previously). On eBay you can find them marked 2300mAh or 2500mAh, but it’s a lie. The cheap ones would last about 1.5 hours. These UR14500 are rated at 840mAh (which is likely true) and 2 of them in parallel ran for almost 3.5 hours. If you want to do the least amount of shell modding and you like the ability to easily swap batteries, I think this is the solution for you.
If you don’t care about switching batteries on the go, and modding the shell isn’t an issue for you, you may want to consider these “1200mAh Li-po” batteries we found on eBay. I have not tried modifying a shell to fit these, yet, but (as shown in the photos) it should be a pretty close fit. I think you can stack 2 of them if you cut out most of the AA compartment. The battery’s width and length should fit. Stacking 2 of them will be a bit snug, so the height may not work (but I think it will). In testing, 2 of these cells in parallel lasted a whopping 5 hours and 10 minutes.
When we get some of the new PCBs in and assembled, I plan to test a stack of 2 of the 1200mAh flat pack cells. Speaking of getting PCBs in, we were informed that the new design should be shipping today. If that’s true, I would expect to receive them in 7-10 days. We have the other parts that we expect to need already here, as a shipment of parts just arrived today.
I would say that puts us at assembling a small set of test boards in about 10 days from now (if all goes well). If they work fine (which will take a few days to determine), then we can start building up units for you guys. If they don’t, then we need to (ideally) find a way to modify the circuit without building a new PCB. We already built in some fallback plans for that sort of thing, but we won’t speculate further until we can test.
Things are looking good. Have a Happy Holiday Season and a Merry Christmas (if that’s your thing)!