I definitely have a love-hate thing with batteries. Orphan batteries lying on the floor is on the list that makes my head explode. So are toys that require the jaws of life to get to the battery compartment. It seems I can never remember which toys take how many and what kind of batteries.
Then it dawned on me after Hunter was born (I've been a parent for how long?), and I was trying to remember "How many for the swing? How many for the baby gym?". Take a Sharpie marker a write on the battery cover the number and size of battery (e.g. 4-C).
Makes is simple for even the 7-year-old to change out those batteries. Now if they'd just put the old ones in the recycling tub!