I put a rechargeable battery through the wash and was wondering whether it's safe to charge anymore or not.

Let it dry completely, and try it. I don’t think it can hurt anything. Either it will charge, or it won’t.

Well I assumed that I should let it dry cuz water + electricity = bad.

ehh… I’d be worried. Water in the components can short the battery and cause it to send a short through either your charger or device. And, if water got in (which likely happened in the wash), stuff can get back out, and battery acid can be rather nasty. I’d suggest being very careful if you want to use it.

and rechargeable batteries aren’t that expensive, are they? NiMH, i assume? If they’re not too expensive I’d definitely suggest a new one.

I supposed I’ll throw it out.