dcamick

As my electrical Charging issue continues on my 65 327 non AC non PB Coupe, I am looking for help with my planned final efforts.............

Recapping what I have done, starting with why I initiated the repair....

Symptom: Charging to 16.5 volts at the battery gauge and battery posts while running at just around idle.

1) Replaced old Regulator and a New ACDelco battery: Resulted in a No Charging issue. Battery Gauge are slightly charging and discharging when increasing RPM's and turning on lights and fans. Battery was only charging max to 12.9 volts, running.
2) Replaced new Regulator with replacement new inexpensive regulator: No change from step #1
3) Tested Alternator: Local Part Store tested Good
4) Questioned first Alternator test results: went to a Reputable Auto Generator Shop test results good. He performed a few different tests on his bench tester.
5) Pulled engine wiring harness. Inspected firewall connector which looked actually perfect. all connector pins were clean and tight.
6) Cleaned all connections, grounds, ground wire from Horn relay to Regulator housing was replaced.
7) Replaced engine (right side) harness purchased from Lectric Limited. Perfect fit. Snapped very well onto the firewall connector no issues. Everything connected to the new harness is working perfectly.....Except the charging system????
NOTE: Old harness was completely repaired at both ends (Firewall and Horn Relay). Starter connections were not seemingly repaired
8) Replaced Horn Relay in the process of replacing the harness just because..............
9) Replaced both - and + battery cables when reattaching new harness connectors at the starter solenoid (cleaned all grounds and hot connections)
10) NO CHANGE in voltage output to the battery. When running and increasing from Idle, 12.7 volts to 13 volts max.
Note: So what I am seeing from the Battery Gauge is consistence to my meter reading at the battery posts

Now, being a novice at this process, but fairly good mechanically, I am determined to finish this! I'm back to the Alternator and Regulator.

Is there a chance that I'm getting a false test result from the Alternator testing? (2 Tests) By the way, I have a 42 amp replacement Alternator on its way........
Is there a chance that 2 Regulators purchased are faulty?
Should I put the Old regulator back on to replicate the High Voltage issue that started this process?

I am setting the stage for a lot of comments, which will be appreciated. But I am going to replace the Alternator, regardless...It should be here in a few days......

Thanks all........I know that is a lot to take in............With my IBM (Inclusion Body Myositis) condition, I'm looking to take a few long drives this spring and summer....

I am hoping to NOT have to go under the dash to the fuse box side of the FW connector.. By the way I checked the fuses which all look good.

Old Harness picture attached for your viewing pleasure.........


Dcamick

65GGvert

Never heard of a 37 VOLT alternator.

dcamick

Sorry 65GGvert.............

"42 amp"

Tiger Joe

did the genny shop confirm the alternator is actually sending the signal to the VR? forget what they call it, the sensing wire maybe?

sounds dumb but I bought a 68 and it came with the original alternator on the floor, guy said he had it rebuilt and it never worked. would bench test fine at the shop, but install on car and nada. I tried installing and same thing, so my local shop actually opened it up- the nuts had been left off the wires internally so while the alternator was pumping out juice, it was never sending the signal to the regulator to turn on

R66

I have never really thought about the charging system when it is 'not'' in need of repair. If the battery is new and has about 12.8 vdc normal charged voltage, will the regulator be calling for any charge?
This brings the question of load during testing - did you have the lights and heater fan on when taking the measurements at the battery?
Back before the VOM became cheap, mechanics would remove the positive battery cable while the engine was running to see if the alternator was charging.
Also, the rear bearing cap on the alternator is slightly magnetized when the alternator is charging.
If everything tests good, did you make sure you have a fresh battery in your VOM test meter?
No charge from an otherwise good system is probably due to an open circuit in the sensing circuit or the charging circuit. Maybe 65GGVert can tell you how to shunt the alternator to force it to charge during which time you can check the voltage at the battery. Or, you can follow the troubleshooting in the GM maintenance manual. This should identify whether the problem is in the charging system or sensing system that drives the regulator.
A temporary conductor from the horn relay to the battery should help elimate an open circuit on the charging side.

GordonR

Its not too difficult to identify the issue on your car. There is a white wire (stator output). when operating correctly will be half the output voltage of B+ on the alternator. Its an input to the voltage regulator. The blue wire is field control. The higher the voltage input from the voltage regulator into the alternator the higher the output on B+. So if the alternator is working your stator voltage should be 6.5 volts. Field voltage should be at least 9-10 volts when output is at your voltage. Also if your battery is not totally charged (static volts @12.6 for at least five minutes with no charger attached) the additional current the battery demands will make an alternator appear week or bad.

dcamick

You are totally correct......Thank you for the conversation.... 2(two) New faulty VR's.......Threw me off...Big time!!! I will be returning the Ordered Alternator after final testing of the Standard Voltage Regulator just ordered......... I will be in touch concerning VR modification at your shop.........Gordon, Thank you!!

plaidside

That was a very popular amperage unit back in the 60's when they first came out with alternators.
https://www.ebay.com/sch/i.html?_fro...agm+alternator

dcamick, I wrote an article on theory and testing of these systems. If you would like a copy send me you email address.
Joe

65GGvert

37 volts was a popular alternator?

stellar

Unplug and test for power at #3 regulator terminal wire. It should be hot with battery voltage at all times key on or off. Good possibility that is the problem

Frankie the Fink

Removing a battery cable to see if the car still runs was common in the 60s but its a bit of a false test (and inadvisable on modern computer controlled cars), the charging system requires the battery resistance as "ballast" to operate properly.

As to the alternator and V/R charging even if the battery is topped off voltage-wise, there are a lot of misconceptions about that; this blurb is from the Mad Electric technical archves:

dcamick

Final Post on this Thread:

Confirmed: 2(TWO) faulty Voltage regulators purchased from different Corvette Parts Suppliers.........Standard Brand Voltage Regulator (solid state) purchased on Amazon worked perfectly........

Thanks all!!!

Vetterodder

Double check the grounding of the regulator. My `65 was charging almost 16 volts, killing the battery and alternator. When I ran a jumper ground wire between the frame and the regulator voltage dropped to 13.5 at idle. I found that the ground wire to the regulator was broken inside it's insulation near where it connected to the regulator.