So will Bluetooth and IR. I leave Bluetooth off and Beam Receive off except when I need them. Makes a significant difference to battery life. I also run with the screen brightness right at the bottom unless I need to use it in bright sunlight.
I use my car charger on my jumpstart battery. That is reserve power for days. There is no reason for abusing your lithium battery. Never store it in a hot car, drain it too low and never charge immediately when the battery is low.
Th-55 U, T/X, TG-50, Handspring Deluxe (3) and PSP user.