So my mechanic told me my alternator was charging but not engugh at idle. It was 11.70 volts. He went through and checked all the wires, I swapped out the alternator and it still was at 11.70. He told me the regulator could be bad. I bought a new one from Vans Auto and installed it today. Now it's charging 12.50-12.80 at idle 600-650rpm. When you rev the engine up or drive it the Ammeter gauge goes from the middle to almost pegged to C like it's over charging. I tried it with the volt meter and it was at 13.40-13.88 with it revved up to about 1500-2000 rpm. So that seems right? But why is there so much movement of the ammeter gauge? It's an NOS ammeter Instruments Inc replaced my burned out one when they redid my gauges.
65 Ammeter now shows overcharge when accelerated
- Thread starter wh23g3g
- Start date
-
65PlumCrzy
Well-Known Member
your voltage regulator can put out upwards of 14.5 dcv at 2500 rpms. can you check at the back of the ammeter guage and see what its input is? Are you testing the DCVs at the battery or somewhere else?
2 Darts
A-body Addicted
I've seen something like that, too. Usually happened when the battery had been seriously discharged. I'd put mine on a trickle charger overnight. That would clear it up most times. If not, I'd put in a (known good) battery from one of the other cars and try it. Sometimes, I'd skip the second test and go trotting off for a new battery.
I've only had one voltage regulator fail in my life (GM), so I have no practical experience testing one. Those are the only two culprits I can think of besides the alternator.
I've only had one voltage regulator fail in my life (GM), so I have no practical experience testing one. Those are the only two culprits I can think of besides the alternator.
65PlumCrzy
Well-Known Member
Good call 2 Darts. A week battery will cause that problem as well. Causes the alternator to work a little harder than normal.
67Dart273
Well-Known Member
Here's the deal. "Running" battery voltage with the battery charged up, (and a good battery, meaning "nothing wrong" with it) should run no less than 13.5, no more than 14.5, and optimum is 13.8......14.2. This is measured AT the battery, warm.
As you add loads, like stereo, headlights, blower, AC, etc, that voltage will try and sag a bit as the alternator gets "topped out" trying to keep up, and of course, worse at low RPM
I would charge the battery and recheck. If it seems amiss, have the battery load tested. If you have a known good battery in another "rig" you can swap that in.
Post back with results
As you add loads, like stereo, headlights, blower, AC, etc, that voltage will try and sag a bit as the alternator gets "topped out" trying to keep up, and of course, worse at low RPM
I would charge the battery and recheck. If it seems amiss, have the battery load tested. If you have a known good battery in another "rig" you can swap that in.
Post back with results
nm9stheham
Well-Known Member
The normal ammeter indications will be C (charging) to some degree when the battery is discharged any amount, as noted. If you drive long enough, the C indication will gradually diminish as the battery charges.
So, the ammeter indications will vary for normal operation; that can be confusing. If you turn on the lights after having driven for a while and the battery is well charged, then it would also be normal for the ammeter to show a slight D (discharge) indication as the system 'settles in' to a lower operating voltage, and the battery discharges bit to reach that lower voltage.
So, the ammeter indications will vary for normal operation; that can be confusing. If you turn on the lights after having driven for a while and the battery is well charged, then it would also be normal for the ammeter to show a slight D (discharge) indication as the system 'settles in' to a lower operating voltage, and the battery discharges bit to reach that lower voltage.
I checked the battery before I swapped out the regulator and it was 12.06 volts. I was concerned the alternator was overcharging when I saw the ammeter fluctuate to c when I gave it even slight acceleration. Is the ammeter always suppose to be right in the middle?
nm9stheham
Well-Known Member
12.06v on the battery is seriously discharged (probably due the system not charging because of to the bad regulator); a good, well charged battery will read 12.6-12.7 volts, after it has been taken off the charger for a few hours, or you stop driving for a few hours, and check the voltage afterwards. Don't check the battery voltage right after driving or taking off a charger; it needs to 'rest' to reach a stable voltage.
With 12.06 volts on the battery, then it is either:
1. Heavily discharged and the ammeter swinging hard to C is normal as the alternator is pushing current into the discharged battery as fast as it can. You would expect the ammeter indication to start moving away from C and towards to middle more and more as you drive it more and more, IF the battery is basically good and was just discharged. After 30-60 minutes or so, it out to settle in near the center.
2. Or the battery is bad in a certain way (shorted or partly shorted cell) and won't hold a good charge. If you charge it overnight and then remove the charger, leave one terminal disconnected, and let it 'rest' for a few hours, and then measure the battery voltage, it should hold at around 12.6 volts. If it has dropped or is dropping after 'restring', then the battery has a bad cell.
The ammeter will only be in the middle if the car is off, or is running and the battery is fully charged. The ammeter is there to indicate current flowing in and out of the battery, not the current in the rest of the car. So if the battery is even partly discharged, then the ammeter will indicate in the C range to some degree depending on how discharged the battery is....
With 12.06 volts on the battery, then it is either:
1. Heavily discharged and the ammeter swinging hard to C is normal as the alternator is pushing current into the discharged battery as fast as it can. You would expect the ammeter indication to start moving away from C and towards to middle more and more as you drive it more and more, IF the battery is basically good and was just discharged. After 30-60 minutes or so, it out to settle in near the center.
2. Or the battery is bad in a certain way (shorted or partly shorted cell) and won't hold a good charge. If you charge it overnight and then remove the charger, leave one terminal disconnected, and let it 'rest' for a few hours, and then measure the battery voltage, it should hold at around 12.6 volts. If it has dropped or is dropping after 'restring', then the battery has a bad cell.
The ammeter will only be in the middle if the car is off, or is running and the battery is fully charged. The ammeter is there to indicate current flowing in and out of the battery, not the current in the rest of the car. So if the battery is even partly discharged, then the ammeter will indicate in the C range to some degree depending on how discharged the battery is....
moe7404
moe7404
after haveing drove a lot of the early chryslers with amp gauges. and now driving a dakota with a volt gauge i like the volt gauge much better. an AMP gauge only shows the AMPs being used. has nothing to do with the battery volts. IMHO
2 Darts
A-body Addicted
IIRC, the car is running off the battery until ~ 1100 rpm when the alternator is producing enough electricity to get involved. Power from an alternator remains relatively flat over the rpm range. A generator on the other hand produces more power the faster the armature is turned.
It amuses me when I hear someone say they left their car running to heat or cool the interior and to charge the battery. The fan is set on high and the car is idling. The voltage may look fine, but an ammeter would be pegged. Who puts an ammeter in a car in this era anyway?
It amuses me when I hear someone say they left their car running to heat or cool the interior and to charge the battery. The fan is set on high and the car is idling. The voltage may look fine, but an ammeter would be pegged. Who puts an ammeter in a car in this era anyway?
nm9stheham
Well-Known Member
Voltmeters are certainly less ambiguous; with an ammeter, you need to know what it will do under a variety of situations; it can give the same indication in more than one situation and mean different things.
I was over there today to some work on my 86 Reliant and I started the Valiant up and let it run the whole time I was working on it. The ammeter seemed to settle in the middle after probably 30 mins. So definitely if driving this car a good many miles away it maybe wise to bring an extra battery and of course fire extinguisher. I've heard about the ammeters melting because of all the current going through them. It was one reason I replaced the dash harness and engine/light harness. It was amazing that the tail lights, dome light didn't work but headlights did while all this was going on and the only thing I could find wrong was the headlight switch securing bezel was loose. I guess it grounds it? I thought it had something to do with my alternator. I tigthened the bezel up, tail lights and dome light come on. It's almost ready to take a drive out in the public streets now.
nm9stheham
Well-Known Member
If the ammeter settled back to near 0 after 30 minutes of running (idling?), then that sounds pretty normal for what was a fairly heavily discharged battery being charged up by the charging system. If you drive it for a while rather than just idling like you did, the charging system will put out more voltage than at idling, and it should go through another cycle of showing moderate to heavy charge and then settling back towards 0 as you drive more and more. Measure the battery voltage after a drive of 30 minutes and then resting as described and see if the battery is now closer to 12.6 v after resting. If that all works out, you have a good battery and charging system and no need to carry an extra battery.....why guess when you can test and know?
As for the headlights and the bezel, I would first suspect that you have a loose taillight circuit connection at the headlight switch and it got moved and made a connection when you tightened the bezel. The bezel does not ground anything not does it have anything to do with the taillights.
As for the headlights and the bezel, I would first suspect that you have a loose taillight circuit connection at the headlight switch and it got moved and made a connection when you tightened the bezel. The bezel does not ground anything not does it have anything to do with the taillights.
-
