71 duster overcharging

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squeek360

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Having an overcharging problem, here's what I know so far.....

fast idle, nearly 16v
reg idle, 14.3ish v (lights on)
disconnect v reg, 12.5ish v
reconnect v reg and disconnect green wire @ field 12.5ish v
any above idle rpm sends it straight up toward 18v and pegs the gauge.
all readings above done with dvom to verify gauge operation

all grounds solid to v reg etc.
no shorts to ground in green output wire
just to be doubly sure, overlayed new wire from v reg to alt to bypass green wire, no change in overcharge condition

swapped in different alternator, no change
swapped a few v regs, no change
installed relay in system tapped into the blue wire and fed from the b+ of the starter relay, no change

getting good near battery voltage at blue wire of reg

more info.... have done amp meter to volt meter conversion with bypass from alt b+ to starter relay
as well, I did the bulkhead connector bypas on that cicuit
also, I have completely replaced my stock gauge cluster with autometer gauges so nothing in there is stock any more
I currently have the pin connector that use to feed the factory printed circuit cluster tapped up and isolated under the dash, and tapped into the harness down below for signal bulbs...

wondering if not having a "voltage limiter" in the system any more due to the replacement of the printed circuit cluster could have anything to do with this?

also, in my research, it seems I should have a dual balast resistor? this car only has wiring for a single, though I placed a dual there with only one side wired up, should I be duplicating the wiring diagram to add the "compensating resistor" into the system? and could this be the problem?

please help, thanx in advance, this is driving me nuts, and I wanna be out there cruising, not fearing my battery will explode aaagghhhh!!! lol
 
the last time i ran into a problem like this on a 71, someone replaced the alt with a double feild wiring, and put a single feild alt on. so what was happenening, it was internally grounding, cause too much charge. i forget the full scope of it, but in my profile there is a thread on it.
 
lol 73'
and I'll have to check that out 'plot


well this is interesting, I had 3 or 4 more voltage regulators lying around, so on a whim I figured I'd just swap them all 1 by 1 to see if I just had a bunch of dead ones... so, I swap in the first 2, no change.... start vehicle, it hits 14v on the gauge, hold this for a hot second, then continues to climb up and peg the gauge...... swap in the 3rd, start car, holds 12.6'ish firm, then I begin to hear a whining noise that I initially perceived as alternator whine, so I go to shut off the car; however, the car wont shut off with the key..... and I had to jump out and disconnect the v regulator at which point the car died :wack:
 
so, I plug back in the original v reg after this happened.... fired up the car, and now noticed that the whining noise (now only a very minimal hard to hear noise that only increases in pitch as the volts rise). I was able to determine that this noise was actually coming from the heater motor.... pulled the fuse for the heater motor, and the noise disappeared, and the behavior of the overcharging seems to have changed and is slightly lower at idle; however, it still pegs the gauge with rpm increase.
 
alright, I went back out there to do some more testing.....(now with the heater fuse removed)..... figured, the first thing I'd do, is remove the relay I wired in as a result of reading things on the internet lol... in the post I was reading, which was on a mopar muscle magazine forum.... and the tech guy said that another thing you can do to stabilize the charging system, is to tap into the blue signal wire at the v reg with a relay, then proceeded to say hook, pin this, to x wire, etc. so I followed these instructions..... so when I went back out for retesting, I had this thought that "hrrrm, if I recall correctly, when researching relays, it seems the way this guy had me wire this, the input/output designation may indeed be back wards", so I figured i'd check this out.... well, I check the blue wire, I have no voltage with the key on, the green, I have 12, so I check resistances in all the wires including the relay, and all is well....... so, I figure the relay is feeding the circuit backwards... which ultimately led to me detecting the heater as a problem..... so, I pull off the relay wires tapped into the blue wire, reconnect the blue wire with it's original wire, start the car..... and woo hoo........ my issue is gone and everything is operating wonderfully.... well, except the heater lol

but yes, now I have to figure out what is up with the heater circuit causing this issue, stay "tuned" :happy1:
 
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