Battery Length of a PSP

Does anyone know? cause so when i go on my trip i know my game play limits b4 i gotta chargeBattery Length of a PSP
also please include the backlight alsoBattery Length of a PSP
Just buy an extra battery.
Well the phat has an average battery life of 5-7hrs and the slim has 7-9 hrs.
well, depends for phat or slim, if fully changed maybe around 7 hours with backlight on low, but please state which one u got
ive got phat (over a year old), use a bit of volume and either highest or second highest brightness and get 6:40 or so
if you play an dont stop you have an average of 4-6 hours
I have a slim and usually play on the lowest light setting, normally I get 6.5 hrs until 20% battery life so I imagine I could have hit 7-7.5 hrs. Im gonna buy a new battery near the holidays
I think my Phat only lasts about 4-5 hours. i have had it for almost 3 years now though.
I got one of the Final Fantasy PSP's last month. I'm only getting around 3 hours of solid gaming out of a full charge. It's really pissing me off. I wish I could get another battery that would last longer.
i usually keep it fully charged so idk
The Slim requires a ''phat'' battery to get the projected 7 to 9 hrs of play time. Without one it has even less battery than the phat. The phat gets around 5 to 6 fully charged.
My Slim usually lasts 6 to 8 Hours on a full charge, and thats not even letting it get down below 10% battery.