Changing batteries

[UTVAK315]

Hey, I was pretty impressed with airz mod with the nesp in the game cartridge so I decided to make one for myself, hopefully with a few additions though. one of which being I wanted to extend its gameplay on a full charge by changing its 5v 1000mah batt to a 5v 2200mah batt meant for 1st and 2nd gen ipods. Im just not entirely sure if that would work as far as charging it through the player and playing properly without any sort of heat issues. Any ideas would be great.