I have a 71 Dart, replaced voltage regulator still discharging, alternator seems to check good. What else?
Step 1: Get a test light (circuit tester) Step 2: Disconnect the negative battery cable Step 3: Connect the test light between the cable end and the battery post, if it lights up, there is a system drain Step 4: Remove fuses one at a time, if the light goes out on a particular fuse, there is the circuit that the power drain is on. You will have to hunt it down from there.
I would recheck the alternator after it has ran for a while and warm, I have come acrossed that problem before and found out the windings in the alternator on the fields would get hot and stop charging and after cooling down it would charge, a rule of thumb as they call it when you change voltage regulator you change alternator on those old chrysler/ dodge products
