16.4 volts at the battery

[shadango]

Ok, here are my results....testing at 1400-1500 rpms, high beams on, heater blower on full, interior dome light on (I didnt turn on the stereo or wipers)

A- Battery voltage. Positive test lead on the positive battery POST (not the battery wire terminal). Negative test lead to the negative battery POST (not the wire terminal. Write down the voltage reading as A.

15.8

B- Alternator output ground side voltage drop: Connect the negative test lead to a clean bare metal spot on the alternator housing. Connect the positive test lead to the Negative battery post, (not the battery wire terminal). Write down the reading as B.

.026 volts on the rear half of the case,  .018 volts on the front half of the case

C- Alternator output positive side voltage drop: Connect the positive test lead to the output (+) terminal on the alternator, attach the negative test lead to the battery Positive Post. Write down this reading as C.

.45 volts average .... .42 to .50  fluctuations

So, going by what the guy in the video said (want no more than .5 volts in C and no more than .2 volts in B)  I am doing ok so far ,, yes?

[734406pk]

Ok so far:

A- 15.8 volts= You are over charging.
B- 0.018-0.026 ground side voltage drop= excellent! You have a clean ground path from the alternator to the battery.
C- .42-.50 Output side voltage drop= On the high side! Do you have an ammeter bypass installed btw? It's not causing your overcharging issue, but we should clean that up after the overcharge.

To continue:
Start the engine and turn on all accessories as before and set idle speed to 1200-1500 rpm

D- VR case voltage drop. Negative test lead to battery negative post. Positive test lead to the metal CASE (not an attaching bolt) of the VR. You may need to scratch a tiny bit of paint off the case to get a reading. Write down this reading as D.

E- Alternator F+ voltage drop. Positive test lead to the positive battery post, negative test lead to the BLUE alternator field wire terminal. Try to slip the test lead probe inside of the slip on connector for a good reading. Write down the reading as E.

F- VR sensing lead voltage drop. Now use your pin through the blue wire at the VR. Connect the negative test lead to the pin. Connect the positive test lead to the battery positive post. Write down this reading as F.

You can shut down the car now.

I suspect that the cause of the overcharging will be within these three test points. Post your readings or any questions when you can. Good luck and work safe!

[734406pk]

The only thing I would add to this is that IF you get a large voltage drop when reading to either of the battery posts, the first thing to check is the battery cable to battery post connections...

they always seem to 'corrode' first, and ground post faster than positive post... (it will build up an oxidized layer between the inside connector surfaces and post surfaces). Use a battery terminal cleaner/wire brush to remove the corrosion, and apply some dielectric grease to the connectors when re-attaching them, to help prevent buildup in the future.

  The alternator positive output voltage drop is on the high side. Corrosion at the battery terminal could easily be the cause. We will test it later. The overcharging is the main issue at the moment.

[shadango]

The alternator positive output voltage drop is on the high side. Corrosion at the battery terminal could easily be the cause. We will test it later. The overcharging is the main issue at the moment.

I just cleaned the posts and connections a week ago or so when I revived this thread.

[734406pk]

I just cleaned the posts and connections a week ago or so when I revived this thread.

Ok. Do you have an ammeter bypass installed?

[shadango]

Ok. Do you have an ammeter bypass installed?

Yes -- did that many many moons ago.

[734406pk]

Yes -- did that many many moons ago.

OK I though so. There is some minor resistance on the alternator positive output side for some reason, we'll get to that later.

[shadango]

OK I though so. There is some minor resistance on the alternator positive output side for some reason, we'll get to that later.

Ok cool.....

As an aside, and maybe I should do this in a separate thread or maybe not....

We were at a car show 3 hours from home over the weekend....car was fine all the way there.  parked and it sat for 9 hours or so.  Started it up and the dash fuel and temp gauges legged to the right.  The aftermarket temp gauge showed normal and of course the car was cold.

Shut it off for a minute, restarted, and it was fine for a little bit then pegged again....drove a ways like that til we took a break, shut it down....next start up it was fine the rest of the way home.

I think I recall this happening once very early in my ownership of the fish.......some 7+ years ago.

The voltmeter gauge still showed the normal high charging status while it was happening.

[734406pk]

Ok cool.....

As an aside, and maybe I should do this in a separate thread or maybe not....

We were at a car show 3 hours from home over the weekend....car was fine all the way there.  parked and it sat for 9 hours or so.  Started it up and the dash fuel and temp gauges legged to the right.  The aftermarket temp gauge showed normal and of course the car was cold.

Shut it off for a minute, restarted, and it was fine for a little bit then pegged again....drove a ways like that til we took a break, shut it down....next start up it was fine the rest of the way home.

I think I recall this happening once very early in my ownership of the fish.......some 7+ years ago.

The voltmeter gauge still showed the normal high charging status while it was happening.

That's a symptom of a bad ground or faulty voltage limiter. I would run an extra ground wire from the dash frame to the car body. The dash lights ground through the dash frame.

[xtopfuel]

 
should he clean and lube the bulkhead

[shadango]

should he clean and lube the bulkhead

Afraid to even TOUCH the bulkhead....what a hornets nest if I screw something up....LOL

[shadango]

That's a symptom of a bad ground or faulty voltage limiter. I would run an extra ground wire from the dash frame to the car body. The dash lights ground through the dash frame.

I am gonna get in there and pull the switch panel and see if the ground is OK....My wipers dont park all the way down and I know the ground at the switch is the first thing to check, so I will be in there anyways.....

I already ran a second ground wire as you suggested, a while back.  Will check that as well.

[xtopfuel]

I had several same issues on my 72 and yes scary removing bulk head but came right off, cleaned with electric cleaner CRC then loads of dialectic lube and all fixed including wipers parking

[shadango]

I had several same issues on my 72 and yes scary removing bulk head but came right off, cleaned with electric cleaner CRC then loads of dialectic lube and all fixed including wipers parking

Did you do just the engine side or the inside side as well?

[734406pk]

Afraid to even TOUCH the bulkhead....what a hornets nest if I screw something up....LOL

Is the dash harness/bulkhead connector the original?