thought i'd share, i have 4 canon LP-E12 batterys, with the clear plastic end cap that they come with i put a piece of loose card inside it, on one side it is fluorescent red and white on the other, when i swap out a flat one i flip the card over so i know which one is flat, i also dated and numbered them 1-4 so i can rotate them each time so i not constantly recharging just one or two. just a little tip