6hrs nonstop play using speakers either game or movie set at 222mhz cpu speed, up to 8 hrs if u use a low voltage Headset, 4hrs if u set the CPU to the max of 333mhz
FYI: Sony actually lowered CPU speed to standard 222mhz just to say up to 6 hrs battery life but the new 3.50FW upgrade unlocsk it to 333mhz ergo seriously cutting down battery life, on another note custom FW allows psp owners to max the CPU to 333mhz via Devhook or the Recovery console
standard battery ng psp is 1800mAh but meron nabibili na 2200mAh(P3-P3.5k) that adds a whopping 30mins-1hr!!(note the sarcasm)