Are you talking about GameBoy Pocket? Cause the battery life on that is over 20 hours. As for GBA and GBA:SP, well GBA is about 20 hours as well and the GBA:SP is just under 20 hours. I actually went as long as I could without recharging my GBA:SP, just to see how long the battery would last. It was almost 18 hours. (I didn't play for 18 hours straight, I did this over a couple of days.) Hope this helps
(4 to 6 hours?! Dude, stop using ghetto batteries,LOL)