So you have a battery that keeps going dead. You have checked all the connections and the cables. They are clean and in good condition. You have replaced the battery or tested it, and it is o.k. and it’s full of water.
You’ve gone on to check or replace the alternator. It charges over 13.5 D/C volts even with a load on it. The A/C ripple is less than a volt (Put a test lead from a volt meter on the positive terminal and the main power output on the back of the alternator, switch the volt meter to A/C. ) If the alternator and the battery are both o.k., and the cables are in good condition, you most likely have a draw. A draw occurs anytime something that should turn of, doesn’t.