[304065]

John,

The fact that your Optima is 7 years old does raise a question for me. I don't have any experience with them that old, but know that a lead-acid would be dead well before that time. That said, hammer it on the 50 amp setting for a few minutes(with it out of the car, please) then stop charging, let it rest for a bit, and measure the open-circuit voltage. Optimas often won't take a charge unless you do this.

So your testing suggests that it's NOT the regulator, and the fact that you've got fairly new brushes in there is encouraging also. Did you clean the corrosion off the D+61, DF and D- in all the important locations?

* Back of alternator
* Pins #11, 12 and 13 in the 14-pin connector, both the female (engine) side and the male (console) side)
* Ditto where the wires enter the chassis through the second 14-pin under the console. This is an unseen haven for moisture and debris, precursor to the crumbly green stuff.
* Bulb holder contacts at rear of oil pressure gauge.

It doesn't happen very often, but remember that there should be TWO paths back to the battery for current flowing out of B+ -- one through the fat red wire to the starter and then through the welding cable to the battery, and the other through the D+/61 (well, there's also a B+ through the engine harness for the defroster, but that's not your problem). The path through the starter is big conductors with lots of surface area and TWO junctions before the battery clamp. The other has SIX before you get to the battery.

That's a long-winded way of saying I think you have a high resistance in the blue wire circuit somewhere. Easy enough to measure from the battery to the D+ on the back of the alternator. I can get my alternator out in 15 minutes, don't forget to disconnect the battery.

Good luck!