I bought some 2300 mah Panasonic batteries with charger at Costco. They last an incredibly long time ! I have an old Garmin GPS12, it would eat AA alkaline batteries. These 2300's last ALL day. I snowmobile a lot. I turn the GPS on at lets say 8AM. I Never turn it off all day and use the light after dark. At 8 PM it is still going strong. AA alkalines couldn't handle this. The 2300's do...
They also last way longer than anything I tried in my digital camera, which eats alkalines in short order too.
Cheers
Danford1