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Follow the bouncing alternator gage needle

AR67GTX

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Tried searching for threads on this but turned up almost nothing under bouncing alternator gage, so having to post my own.

66 Satellite Hemi I just got started today after replacing all of the harness except the rear one, and a whole lot of other stuff. Standard round back alternator, professionally rebuilt and bought from a forum member. Old, black voltage regulator that I haven’t changed out. Haven’t done any voltage checks as I’ve been concentrating on getting the distributor positioned to where I can time it. I dragged the battery down pretty good before finally getting it to start and the gage was showing pretty much full charge but it was gradually coming down as it ran - all that looked perfectly normal. But then I started noticing twitches in the gage needle - always dropping towards the middle of the gage and then back to wher3 it was showing to be charging. No bounces to full scale - just fro mid-point charging position to middle of gage (no charge) and back. The bounces are random and will sometimes stop for a bit and then resume in random fashion.

Does any of that sound familiar. I will double check the mount screws and run a separate ground. Probably need to just find a solid state regulator to put in it?? Any other things to check?
 
from FCBO cantflip
3 easy tests.

Do all with the car running, turn on every thing electrical you can.

1- DMM on A/C volts. Test at the battery terminals... if you have more than .5 volts you have a diode issue.

2- DMM on D/C volts. Test with one lead on battery + and one lead on alternator B+... this is your voltage drop for the alternator to battery circuit... .5 volts or less is good.

3- DMM on D/C volts. Test with one lead on battery - and one on engine block and then the alternator case... this is your voltage drop for the ground... no more than >5 volts and lower is better. The difference between the drop to the engine block and the drop to the alternator will show if you are getting resistance from paint or corrosion where those parts bolt together (alt is case grounded to the block).


If you like, you can redo #3 while cranking... that would be the heaviest current on the ground... still no more than .5 volts and smaller is better.


 
If it's a factory guage, it's an ammeter. This shows "draw" not charging. I believe it works like this, If it's pointing to the right, there is a draw on the system but the alternator/regulator are keeping up with it. If it's pointing to the left, they are not keeping up w it. Take a multimeter set to DC and test at battery while running and you'll see the voltage being put out by the alternator/regulator.
 
Yes, should have been clearer - factory amperage gage.
 
I had the same problem on a 68' Hemi Road Runner that was using the original charging system, no modifications. I replaced the original mechanical style voltage regulator with a solid state one and fixed the problem.
 
I just ordered a solid state, original appearance one just to have as a backup. I’ll do some more checks next time I get it running.
 
non solid state voltage regulator - it regulates by going on/off, that causes the needle to bounce. Solid state voltage regulator should fix the problem
 
Just take the cover off of the mechanical regulator, and spray it with some electronics cleaner. I prefer Electro Wash px. But any electronics cleaner will work. Deoxit is another brand amplifier guys seem to like. It’s just sticking.
 
Yes clean the contacts in the regulator. And you know there are adjustments outlined in the service manual, right?

1969 Dodge Charger Coronet Dart book page 8-30

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Yes, but I hadn’t thought about cleaning it. May give that a shot as I have a can of Deox in the garage.
 
I cleaned the regulator with deox and once inside remembered I had it apart last year. It’s a mechanical unit and not exact to the originals in design inside so the FSM wasn’t of much help. The deox cleaning may have finished it off as it would seem to work fine for about 30 seconds after starting the car - showing about 14 volts at the battery. But then it would seemingly stop working, the amp meter gage drop to a slight discharge and the voltage at the battery would go to 12.6 volts. I did this 3 or 4 times with same results. Should have the solid state regulator in a few days so I’m just going to wait on it and hope it takes care of things. Thanks
 
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