They do that. There's a reason you're not allowed to put a lithium battery in your checked luggage on any sane airline: At least in the cabin, it is seen and can be addressed immediately. Personal opinion: It shouldn't even be in the overhead, though: You bring a L-Ion battery on a plane, you put it on your crotch.

It is a China L, but these rules are already in place because they know these things do happen often enough to bother to make rules about it.