Battery won’t charge

[Dan B]

1969 coronet 318. Pertronix ignitor 3, pertronix coil, two field alternator, 71 style voltage regulator, the alternator won’t charge.
I have 14.2 at alternator stud. VR case has good ground (measured case to neg terminal and it is .01 ohms)
The VR is brand new. Alt is brand new.
At about 2300 rpms I have 14.4 volts at alternator, at VR plugs, going into Bh connector. Coming out of bh connector and at battery I’m only between 12.5-12.7. Could this be my ammeter guage is bad?
I can’t figure it out please help.

 

[Don Frelier]

You are down to the wiring, gauge and bulkhead.
If you can get to the ammeter check both sides there with a voltmeter.
If you have the same results your ammeter is open circuit.
You are close.
If the meter is open a temporary fix would be a jumper with 8 guage wire, I prefer stranded copper.
Good luck with it.

 

[Nacho-RT74]

If the ammeter was open the car wouldn't start. The ignition circuit is AFTER the ammeter coming from batt.

what kind of reading do you have on ammeter ?

Check bulkhead conectors. They can get voltage but not amperage due a poor contact. Amperage is what charges the battery.

Since the starter motor is directly feeded from battery, the ignition switch can still trigger the starter relay with a poor load path and start up the engine with a poor contact. But recharge the batt is a bit harder.

Sure the ammeter is also something to check. After all these years of bad use and abuse, the internal shunt can get stretched so the studs which are pressed in beging to get loose.

 

[Dan B]

You are down to the wiring, gauge and bulkhead.
If you can get to the ammeter check both sides there with a voltmeter.
If you have the same results your ammeter is open circuit.
You are close.
If the meter is open a temporary fix would be a jumper with 8 guage wire, I prefer stranded copper.
Good luck with it.

Ok so 14.6 on one side and 12.78 on the other side. Guess my guage is bad

 

[Don Frelier]

If the ammeter was open the car wouldn't start. The ignition circuit is AFTER the ammeter coming from batt.

Correct, didn't think of that one.
But the reading difference sure seems like it's not passing enough current to raise the battery voltage.
I would try and remove, clean and tighten the connections.
If that doesn't work try the jumper.
Sure seems like the problem is at the ammeter.

 

[Nacho-RT74]

If the ammeter studs are loosen inside can still be fixed. Will post about this on a later reply. There is a thread around about the welding job of these studs to the internal shunt.

The Ammeter is a gauge hard to beat, but when is required, needs a good mantenience service being serious.

 

[Dan B]

It’s the ammeter I bypassed to test and with gauge Bypassed I have 14.62 V at the battery.
Thanks guys for the help.

 

[Don Frelier]

Excellent.
I don't charge on Mother's Day so you're in luck.
Have a good one.

 

[Dan B]

Excellent.
I don't charge on Mother's Day so you're in luck.
Have a good one.

Appreciate it man. Cruise on

 

[Nacho-RT74]

It’s the ammeter I bypassed to test and with gauge Bypassed I have 14.62 V at the battery.
Thanks guys for the help.

where you bypassed it ? if at engine bay, still the bulkhead conectors are in the game.


here is a way to rebuilt ammeters. Sometimes the pics on this thread doesn't come up, but basically what they make is weld the studs to the shunt

https://www.dodgetalk.com/threads/bullet-proof-your-ammeter-a-how-to.252130/

I fixed a 70 charger ammeter just adding a small ammount of lead between studs and shunt with a 45 watts soldering gun. After a nice alt upgrade the ammeter won't be a problem anymore since barelly will get charge or discharge reading. This is the major failure on Mopar Charging system, the poor charge capacity at low speeds causing a constant battery drain which the alt tries to get back when revving up. Is an unnecesary stress added to the system which is solved when you have a nice alternator able to source around at least 45 amps at the lower speed as posible ( iddling ). Some stock alst barelly are able to source this at high speed and maybe 25 iddling.

Then a parallel path between alternator and ammeter black end and you'll be pretty much safe with it

 

[Dan B]

Thanks for the info Nacho-RT74 I will tackle this at some point.