The manual doesn't specify a rechargeable battery. It just says a CR2032 Lithium battery. Unless all such batteries are rechargeable? I guess I'll find out since I just replaced the battery in mine and it's an Energizer CR2032, but it doesn't appear to say rechargeable anywhere on the packaging or the battery itself. I guess if it kills my calculator, it had a good run....

EDIT: The original battery that I took out of the calculator doesn't say rechargeable on it either.