Ammeter stays at +20

[66FBCharger]

This question is about my '69 R/T. It has an electronic voltage regulator.
I got the car running (after an ignition problem) a few weeks ago. I charged up the battery since it sat all winter. I took my daughter to the prom in the car with no issues. I drove the car to work today and the ammeter reads +20. I figured it would go down to almost 0 after driving a little bit. I drove the ~25 miles to work. The ammeter is still at +20.
So, now I am at work with limited supplies. I did find a new electronic regulator in the car that I had packed for last years trip to Carlisle. What are the odds it is the regulator?
I checked all the wiring and it is all connected and no wires are pinched, broken or grounded out. If I put the headlights on it drops down to ~+10.
I'm going to swap the regulator in the parking lot before going home. What kind of damage could I cause driving with the car at +20 if the regulator doesn't fix the problem?

[Pete in NH]

Hi,

It could be the regulator or a few other things. A poor regulator ground or some type of voltage drop in the wiring system between the battery and regulator. The next step should be to put a voltmeter across the battery and see what the actual charging voltage is. You should see something between 13.8 and 14.5 or so volts.

There is also the possibility the battery has a bad cell in it. The voltage measurement should tell the story. If the voltage range is normal and the battery constantly charges at a high rate over an extended time, it likely has a bad cell.

In any event , I would not drive the car too much until you find out what is going on or you risk damaging a good battery or burning out a lot of lamps.

[66FBCharger]

Hi Pete,
Thanks for the reply.
Like I said, I am at work around 25 miles from home. I will try to see if I can find someone who has a voltmeter I can use. I'll check the charging voltage, then change the regulator and check for voltage drop between the battery and regulator.
Is there a definitive way to determine if you have a bad cell in the battery?
So, I can burn bulbs out from the higher charge rate? I have LEDs. Are those as prone to burning out as an incandescent bulb?

[66FBCharger]

So I went out to check the car out at lunch. With the car running I got 12.9V at the battery. I pulled a lead off the battery with the car not running and got 12.2v. I decided to change the battery because it was from 2005. I went to NAPA and got the correct Group 27 battery. I installed it and checked the charging. I was getting ~14.2V and the ammeter was dropping from +20 down towards zero. So the problem appears to be fixed.
The only issue I ran into is the battery hold down j hooks are about an inch too short. I'm guessing they are not the correct ones for the car. Are the j hooks the same whether it is a Group 24 or Group 27?

[71 SE3834V]

.... I decided to change the battery because it was from 2005.

Guess you got your money out of that one. My wife's '02 Dakota went 13 Michigan yrs on the original battery.

Does the battery have a tray on the bottom that comes off? Many aftermarket batteries have this to accommodate different vehicles. I had to remove the tray for the battery I put in the '71.

[myk]

So I went out to check the car out at lunch. With the car running I got 12.9V at the battery. I pulled a lead off the battery with the car not running and got 12.2v. I decided to change the battery because it was from 2005. I went to NAPA and got the correct Group 27 battery. I installed it and checked the charging. I was getting ~14.2V and the ammeter was dropping from +20 down towards zero. So the problem appears to be fixed.
The only issue I ran into is the battery hold down j hooks are about an inch too short. I'm guessing they are not the correct ones for the car. Are the j hooks the same whether it is a Group 24 or Group 27?

The J hooks I got in a Mopar battery tray kit are too long; I was worried they might punch through the hood...

[Nacho-RT74]

Do you have some added accesory sourced from the batt?

[66FBCharger]

Do you have some added accesory sourced from the batt?

No. Everything is stock even the AM radio.