Originally Posted by madpogue

CR2032 isn't exactly a "special" battery. They're in tens of millions of car remotes, etc. Almost literally a dime a dozen. OTOH, they are disposable. At least with C or AA/AAA, you can buy NiMH rechargeables. Only downside is the size; hidden in the tank, they take up precious space that would otherwise hold dilithium crystals.