Ok, that's a better indicator that the battery is not the fault. Good so far...
And something that can drain the battery overnight is almost always the regulator and/or alternator diodes. You could likely feel the alternator as being at least warm long after the engine has been running. This indicates some current flowing through the unit.
Leave the battery connected and disconnect the regulator to see if the drain stops.
Or quicker, test for power on the Orange field wire at the back of the alternator, OR up at the connector if you can access the backside while it's still connected.
You should see these readings that may have been discussed before:
1. Orange "F" wire should have zero voltage with the key OFF.
2. Yellow "A" wire should have full battery voltage al the time.
3. Green w/red "S" wire should have zero power with the key OFF, but battery voltage with the key ON.
If you find power on either the Green wire or the Orange wire with the key OFF, something is wrong with the wiring or the ignition switch.
If you find no power on the Green wire but have power at the Orange wire, the regulator is likely defective.
If you have now power on the Green wire, but power on the Orange wire with the wires disconnected from the regulator, likely the alternator is bad.
If you have time for the "long test" you can disconnect the regulator and wait overnight. If the battery still dies, your alternator is bad.
The only problem with the long test is that if you keep draining your new battery you're not doing it any good. If you start early and check it just a couple of hours later you can see that it's draining or not, but not so far down it hurts the battery.
Paul
