I recently noticed my stock amp meter pegs to charge with acceleration. When I let off the gas is comes down to neutral but as soon as I accelerate it revs past the charge position. It is a bone stock 1963 Chrysler 300 with a 383. Any help is appreciated.

Sounds like the reg is either losing ground or bad.Does it still have the points type reg?Ig it does replace it with the new solid state that looks like stock.On them I like to replace the brushes also as its an easy job.Rocky

the reg is fried (its full fielding) & this high voltage will fry things in short order. do NOT drive it. get a replacement ASAP & most parts house replacements are electronic (which is far better than the problematic OE electromechanical type which have the wire wound resistors on the bottom side).

yes. It still has the points...Excuse my ignorance but am I replacing the voltage regulator?

yes

Your fine bro, the OE reg is a "points" type that Rocky was referring to which is the electromechanical type. get a new reg at your parts house, make sure the base is grounded well when you install it & you'll be good to go. EDIT just make sure the parts house reg they pull does not have the wire wound resistors on the bottom which highly likely it will not.

Not sure how you guys can jump to that conclusion.
One likely common regardless of the cause is that the battery is low. Then when the alternator output increases with rpm, the battery sucks all the juice it can get. That's why you see the ammeter indicating high charge.

First - Slowly charge the battery on a charger to reduce the chance of overloading the charge circuits wires and connectors.


Possibilty 1. Battery is not getting charged at low rpm because the output is weak. This could be one bad diode and thats why with increasing rpm the alternator output increases.

Possibility 2. Battery not getting charged at low rpm because the alternator's field is not getting enough power at low rpm.

A loose or oxidized connection in the field circuit is a possibility too. This includes the internal ground that completes the field circuit.


Test if providing field power causes the alternator to produce power at warmed up idle or a little above. That is jump a wire from regulator in to regulator out and bring the rpm to 700 or so.

The original regulator is points style. Easy to open up and see if the points are sticking, dirty or burned. For the first two, clean up with a piece of paper or fine abrasive like crocus cloth.

Shopmanual will have all the details of adjusting.
Chrysler Tech series may be useful as well.
http://www.imperialclub.org/Repair/Lit/Master/index.htm
Look at #169 for example to see the voltage reg

^^^ Agreed, it ain't 100% (but is real close).

Posibility 3. Loosen connections on the charging system, i.e bulkhead conector began to melt and lost the good conection.

A full fielded alt will give max output ( according with RPMs ), but not a discharge reading

99 % of the times its the reg.Most points types I had went no charge But many went full charge.Unless the battery was run way down it should charge for a bit then go down.Had quite a few that lost ground because the screws lossened from age and time.Rocky

The regulator is not expensive and easy to change. Try it.
I see a similar issue with my Roadrunner, evening car shows extended idling, dim headlights, the old alternators didn't put much power out a low speeds and can draw the battery down.
it may charge at full capacity at higher speeds for some time to bring the battery back to full charge.
been that way since the cars were new.
Completely different than modern cars, that have capacity at idle to keep up with all the draw.

Back in June, I went out early on a Sunday morning to fire up the Challenger to head off to an event,,,,Mopar Alley annual car show.

Got the dreaded click, click telling me that either the starter had failed or more likely a dead battery. Turned on headlites, nothing, nada.

Hooked up battery charger for 1/2 hour,,,tried to start again. Still nothing. Tried to jump from another battery. No go.

Then remembered emergency lithium battery pack in the trunk. Hooked it up, engine fired right off and I was on my way. These things are amazing. Recommended for everyone to carry.

Car battery still almost dead,,,likely from dome light on for a few days,,,tested under 11 volts.

Driving on the way to the event, amp meter is pegged at full charge, now I am worried that I am going to burn up the alternator best case, or worst burn up the car because of excessively long period of alt current passing thru amp gauge.

Nevertheless, important show so we soldiered on. After about 15 miles was relieved to note that pegged amp gauge was slowly returning to normal center, which by the time of reaching event site it had finally done.

This goes along with what others have posted on the behavior of the amp gauge is that possibly a pegged gauge is just illustrating that the alternator is doing its job.

A pegged gauge could possibly be showing a defective battery that is not properly signaling back to the regulator that it has reached full charge,,,all the alternator's current is basically going off into a black hole.

Likely an electronics type engineer can set me straighten this if my theory on this is unreasonable.

Likely easier to just replace a low cost regulator as an initial step as others have suggested, rather than sorting this all out

I replaced the voltage regulator and the problem appears to be solved. No pegging with multiple revs in the garage. The battery is acting a bit weak upon initial start but I have it on a battery tender. Let's see if that helps... Thanks for the help moparts family...

the reg?

Sxrxnr. I agree with everything you wrote. Good real life example.



The alternator should not burn up. It may run warmer because its providing closer to its max output for the given rpm for extended period of time. But stock units have adequate cooling for their original internals. Nothing to write home about but nothing to worry about either.

You are correct to be somewhat concerned about wiring of the the charge circuit if it is pegged. From the main junction to the battery there are several connectors and the wires themselves are not particularly heavy. The wires are protected to some degree by the fusible link. The old connections are potentially the most vulnerable to developing resistance; oxidation or loose terminals.

If the ammeter peggs to charge, best move is to shut down. Pegged indicates its (current) is above the design limits for the circuit even if everything is in good shape. Letting the battery cool down (especially with an AGM battery) helps it recharge.
If the meter showing charge, but less than pegged, run at low rpm and or turn on headlights. If the meter doesn't come down over time then the VR is still calling for recharge because the battery is not taking the charge or is really low. Shut down, let the battery cool.

If the ammeter pegs to discharge, shut down asap. The battery can provide a couple of hundred amps if asked. The fusible link should deny it, but if its asked for just 50 or 100 amps it might be not open before something in circuit - usually a connection melts open.

Nacho's diagrams of the Charging Circuit make it easier to see the connections. no pun intended..

Excellent analysis, answers concerns/questions that I and likely others have had,,,,particularly potential risks associated with over loaded circuitry of under dash wiring.