A drain that will run the battery down in a few days is big enough to power a 12 volt test light. Disconnect the ground cable and connect a test light between the cable and the battery post. If there's a drain, the light will burn. Start disconnecting fuses and/or circuits one at a time until the light goes out, then trace that circuit to see what's causing the drain. Leaky diodes in an alternator can cause this type of drain, and the alternator will still do a pretty good job of keeping the battery charged up.
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!