If you put in a lithium coin type battery or anything else non-rechargeable
DO! NOT! FORGET! THE! DIODE!
If you do, the charging circuitry will make the battery explode. No kidding.
Better use a germanium diode or the voltage drop of a silicon one will make the battery unusuable long before it's empty.
Another alternative is to use a quality NiCd or NiMH battery with a measure of cabling so it gets out of harm's way.
