Reader, [Fox9p3400], opened up an Xbox 360 controller battery pack so we could all see what goes into one. It contains two Sanyo 2100mAh NiMH AA rechargeables (Model HR-3U 1.2V). In addition to that, there is an Atmel microcontroller (not pictured) and the copper temperature probe you can see above. He has more pictures on Photobucket.
Adding extra battery capacity to hybrids is becoming pretty common, but this one is better than the average lead acid trunk fest. The pack was built from three prius NiMH packs picked up from salvage yards. These batteries can’t simply be bolted together, but with some research and effort you can save some nickel from the junk yards and cut your fuel bill.
