Kevin

To see if you have a blown diode. Get your voltage meter and set it to A/C voltage and measure/read the voltage at the battery. Better yet at the main jump lead in engine bay.
You will see some A/C leakage but if you see .6 volts and above you have a blown diode. Typically if bad you will see 1.0 plus A/C volts or greater.. A/C current will wreck havic on our electronics..

theprf

Check the engine ground strap.
Sounds like the alternator is putting out good voltage, and the drop is from the alt to the battery.
If you have long enough test leads, with the engine running, probe battery "-" to a metal part ON THE ENGINE like the power steering reservoir.
Then battery "+" to the engine "+" jump terminal.
If the voltage is over 0.3 to 0.4 there is a cable issue somewhere.

s65e90

Why does every thread on this site turn into a novella ? This sounds fixed. If you're looking at the dash gauge, remember, it's not pint point accurate and it's designed to have a range, meaning you may not see the most tiniest of movements so it's not always jumping around, so it's more of just a reference. I would trust the Durametric more for an accurate reading. Again, clean all contacts, and drive the car. If it was dead, low, it needs a good long ride to really get everything back to normal. Idling the car for a few minutes won't do it.

Also, as stated prior, you do see a voltage drop on these cars, cause the battery is in front, but you're running a cable to the back and measuring from that point, so a drop is seen from front to back. If it starts healthy and not straining to crank. drive it. Keep a jump pack handy just in case, but new battery and new voltage regulator you should be good to go.

(P.S. a good old school shop who rebuilds will check the alternator properly under load for free).

911mhawk

I rekindled the thread last night after my battery died, appreciate all the responses, thank you.
Have a new Bosch regulator in hand and my battery was on the charger all last night so this afternoon I'll see what tests out before pulling the alternator,
My office is close to an old school rebuilder that can test tomorrow before re-install to confirm diodes are not the issue if that becomes necessary.

spooltime

To close the loop on this thread, today I installed a a correct version re-manufactured Bosch alternator and doing so resolved the low charging voltage issue my car was experiencing. Before going this route, I replaced the voltage regulator and did numerous voltage drop measurements - and couldn't find issues with the engine ground, nor did the new regulator improve the voltage output. That left the original alternator as the main suspect in causing the problem, which it was. The alternator probably had some faulty diodes and wasn't providing full voltage output. I'm now getting a nice and steady 13.7V across the battery terminals with the engine running instead of the 12.1V I was getting prior to replacing the alternator. The other positive was the benefit of a learning curve. It took me about 4 hours when I did the alternator R&R the first time to replace the voltage regulator. This time, knowing what I was doing, I knocked out the R&R in under 2 hours.

I'm debating on whether it makes sense to have the old alternator rebuilt by a local shop so I have a fresh spare should the need ever arise, or whether to send it back for my $80 core charge. Anyone kept their old one and had it rebuilt for future use?

Dock

I'd send it back.

Carlo_Carrera

Send it back, collect $80.