I've been playing around with some different sized cells to build some physically smaller battery packs for my QCX-minis. I only use them about an hour or two at a time, so I don't need a massive power source. However, most store-bought (relatively cheap) LiFeP04 batteries start around 6Ah. So I began looking for small cells to build a custom pack or two.
I found some neat little LiFeP04 cells the same size at AA alkaline cells. Since the are 3.2V each but still fit anything that takes a AA, I had to have a talk with the family to make sure no one accidentally used the "purple" batteries! I also bought a universal charger that could charge them. The unit also charges NiMH, Li-Ion and NiCad batteries with the flip of a switch.
I bought a few balancing units and then complexly over engineered a battery pack. It worked, but it not practical. So, I ordered a case with a lid, power switch and power cord and simplified my life. Now I