I partially opened mine up to look at the battery. I could not get it all the way open because one of the flat flex cables seemed to be glued to the outer housing. However, inside it seems that there are two separate batteries, taped together, presumably wired in series. Each is most likely a 3.6volt, resulting in a total 7.2 volts for the tablet. So if a there was a popular cell phone, or digital camera, or similar device, that was relatively thin, rated at 3.6 or 3.7 volts and somewhere around 1500-2000mAh that would be great and probably work. The replacement process would be non-trivial, however.