Try disconnecting the big "charge" lead at the back of the alternator and leaving the rest of the system intact. It's possible there's a leaky diode in the alternator that's putting a constant drain on the battery. Be sure to fully charge the battery first- - - -it should have a specific gravity of 1.265 and/or an open circuit terminal voltage of 6.3 volts or more. Anything less and you'll need to do more charging or replace the battery.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!