Having the blackened nubbin of a cold dead heart is SUCH an inconvenience this time of year.
When, lo! And Behold! I stumbled across this!
Power Wheels Single Battery Toddler 6 Volt Charger
The product description seems to indicate that one is not supposed to plug the Actual Toddler into the wall.
For use with certain 6-volt Power Wheels vehicles. This charger must only be used with a Power Wheels Toddler 6-volt lead acid battery (sold separately).
Well, so much for Truth in Advertising. It DOES say it's a "6 Volt Toddler Charger!" What was I supposed to think? Never mind, then.