Check your /cache partition size. If the updates from Augen haven't modified it, then the size of /cache corresponds to your battery size. Don't ask why but after a survey of 15 people the results were the same for the two sizes.5MB = 2100 mAH20MB = 1500 mAHDon't ask me the command to check the partition sizes on your GT, I don't remember them. Linc should know though, or someone else on this forum.Also, it wouldn't help to use a cell phone battery. They are usually low power batteries and won't work without a combination of at least 4 of them (a parallel set of two sets of two batteries in series). The battery in my Samsung Eternity is a 3.4V/1300mAH battery and the phone requires a 3.4V/800mAH battery.To use my battery as an example, I would have to have 4 of them setup in a somewhat of an H shape (for visual help) and it would provide 6.8V/2600mAH. You get 6.8V by putting two in series. Then to get the 2600mAH, you take your two sets of 6.8V series batteries, and put them in parallel (connect their plus sides together and negative sides together) then insert them back into the GT as normal. You could buy a small transformer (about the size of a large marble) to trade off some of the current for more voltage. I'm not sure what the GT requires though for it's voltage minimum.Another idea would be to take the battery in there and just add another set of cells on (like cell phone batteries) to raise the overall power rating. You would just need to make sure the voltages all match up, then their mAH ratings would add together, giving you more time between charges.