Buy a pack of Eneloop's. My Garmin takes two AA's so the $7.99 to $11.99 depending on where you buy them 4 pack of Sanyo Eneloop's gives me one set in the gps and one spare set. I tend to turn mine on and drop it in a poclet when we go any place and let it log. SO I just swap the batteries on a friday night before the weekend's travels and drop the somewhat used set in the charger and pull them out Sat morning before we leave.