I came on to ask a similar question, take it by responses to yours, zero, that we are on our own here...
My 87 decided to discharge battery when not in use, so I unhook it when she sits, a hassle, until I get a chance to figure out what the common things that go wrong when the key is off and a battery drain, seems to charge well when running. Took out a brand new Gel battery on me.. garden tractor battery strapped to rear grab bar for now, looks ghetto...