I bought an adjustable voltage regulator because the originali thought was not working it homed out a 1.53 still getting volt Spikes and it Burt up my pertronix when I saw it hit 18v. 1.75 ohms is supposed to produce 13.75 volts. So even with the old regulator it is still spiking and I have a brand new battery. Any ideas why it won’t stay below 14v any throttle and it will hit 15.5 and up quick. Toasted my pertronix before I made it 5 miles. I picked car up from having it completely rewired. Bumper to bumper.
16volts plus.
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1WildRT
Well-Known Member
Is it a stock style alternator & separate regulator? If so pull the plug at the voltage regulator... Does it stop charging?
If not unplug the green wire at the alternator & see if it's charging...
If so, test the voltage at the blue wire in the regulator plug.... It should be the same as battery voltage, if it's low the alternator will over charge... Also test for resistance between the voltage regulator case and the negative battery post... Resistance there will also cause an over charge condition....
If not unplug the green wire at the alternator & see if it's charging...
If so, test the voltage at the blue wire in the regulator plug.... It should be the same as battery voltage, if it's low the alternator will over charge... Also test for resistance between the voltage regulator case and the negative battery post... Resistance there will also cause an over charge condition....
4spdragtop
Well-Known Member
Blue wire connection is open somewhere if going over 16 volts. Shy of 15 shouldn't fry anything...
Over the years this has been covered, & there's another thread where it's being addressed, there are multiple overcharging threads in the electrical & ignition on this.
It can also be the wires that are bolted to the gauge or the gauge itself. Put your hand on the back of the gauge. If they feel loose the plastic on the gauge/dash is melted away. Kim
MDchanic
Connoisseur d'Junque
So you paid someone to completely rewire your car, got it back, drove it 5 miles, and it was making an impossibly high voltage and burned up your Pertronix pickup?
Sounds like you don't need to troubleshoot this at all.
Sounds like whoever rewired your car needs to fix his mistakes and buy you another Pertronix.
– Eric
Do you think you could tell us what you are working on? Make, model, and year? Yeh, cuz, "it's important."
I have no idea what this means
"it homed out a 1.53"
"1.75 ohms is supposed to produce 13.75 volts."
And I agree, if you "picked it up after having it completely rewired" you probably ought to be talking to those guys.
WHAT ARE YOU WORKING ON? What is the alternator / regulator combination?
Is this rewired to mimic original wiring, or is this a completely different harness like a Painless "universal" thing?
The fact that you said the "stock" regulator produced less output indicates that the harness is allowing the VR to have control, IE that it is not "full fielding" to full output. This indicates the VR may be seeing a voltage drop. It may be as simple as a worn ignition switch.
A couple of things to get you started. The VR MUST be grounded to the same voltage potential as battery neg. MUST. This means, EG that the battery must be grounded well to the engine block for the starter, and at some point a good large gauge wire must be jumpered from either the battery or the engine to the car body.
Get a meter, turn the key to "run," engine stopped. Access as close as you can to the VR IGN terminal. Hook one meter probe to that and stab the other into the top of the POS battery post. Take a reading and post it. You want that reading as low as possible. Whatever that reads, "lets say" 1.5V, will ADD that to the nominal 14V setpoint of the VR. This means that a 1.5V drop will cause the system to produce 15.5 at the battery
Please answer the questions
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1WildRT
Well-Known Member
Well Stated....
71 demon. Replacement oem alternator. Yes a painless new wiring harness. He did a great job very clean solid connections. Every wire replaced. New fuse box two new circuit breakers. new autometer gauge set. The only ground I see to the vr is that it is bolted to the body. I have three vr’s one ohms out at 3.0, one is able to be adjusted and the lowest I can get it is to 1.67 ohms. The original vr ohms out at 1.50. The battery was relocated to trunk. There is a ground directly to head and a ground from there to fender. It is a solid half inch conductor. The ignition switch was replaced because the one in the steering column was definitely worn out. So new remote starter switch as well. It idles at 13.75 but any throttle brings it up to 15v but full throttle or even quarter throttle it will hit 16 and I shut it down now. At the battery I measured 14.1 volts at idle.
MDchanic
Connoisseur d'Junque
MDchanic
Connoisseur d'Junque
So it's not high resistance between the battery and the sense wire of the regulator.
The guy who wired it needs to fix it.
- Eric
The guy who wired it needs to fix it.
- Eric
Not sure "we know that?"
Thank you very much
Again, this could be as simple as a drop right in the ignition switch. Realize that the sensing for Mopars is in the IGN lead to the VR, as there is no separate sensing. Any drop at any point in the path from the battery, through the harness, connectors/ terminals, switch, and finally to the VR IGN terminal (including the ground circuit) will result in overcharge.
THERE IS A SMALL chance that you have a battery problem.
Go back to where I talked about VR drop
1...With key in "run" and engine stopped, you need to build an extension wire, and this can be small like 18, to go from the battery positive post right at the battery, clear up front to the VR. Hook one end of your meter to your extension wire. Hook the other end of your meter to the VR IGN terminal or as close as you can get, AKA the switch end of the ballast resistor if you are using one, or the blue field wire to the alternator. You will now be measuring the drop to the VR all the way from battery pos. to that point. You want to see as low a reading as possible, and again whatever that reads will be added to the VR set point. Make this reading WITHOUT disconnecting anything, such as the alternator field or VR
If that reading is reasonable, "let's say" .3V or so, I would try to temp swap in a known good battery, and or try yet another STOCK VR.
You can also measure drop in the ground circuit. This would also require an extension wire for your meter. Clamp your extension wire direct to the neg terminal of the battery. This is harder with a system acting up.
Now with engine running at fast idle, and you are going to have to regulate this so the system is not running more than say, 15V, Connect your meter to the extension wire to neg battery, and then stab the other probe hard into the VR mounting flange. The reading you'd like to see is very low, zero volts. would be perfect This will show whether with charging current in the system, that the VR actually has a good ground path to the battery neg.
Basically, you want to make this test first with any accessories such as headlights, heater, etc off, and again with these loads activated.
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Thread moved to Electrical and Ignition forum. 
What is the wiring path to the say, accessory buss and ignition switch from the battery, since it is trunk mounted? Is that tapped off the starter, or maybe, a too small wire clear to the rear, or what?
Is it a newly constructed car with fresh paint? Regulators need a "GOOD" ground to the firewall and a bad ground or one with too much resistance will cause overcharging. A sheet metal screw in a freshly painted hole is not a good ground.
I will check on that not sure.
The paint was sanded off on both bolt holes. I am run a ground wire to the be from the ground to the head? I will do the other tests as best as I understand them. For a bodies only got me this far. Except for the wiring that was out of my league. It took him 5 weeks I think this was why he was hesitant to let it go back to me.
I wanted a good ground and a solid mounting for the ECU on my 64 so I used a couple of Nutserts.
You probably got a good ground. A temporary jumper to the block wouldn't hurt just to make sure.
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Also, checking a voltage regulator with a multimeter is not likely to get conclusive results. The measurement will depend more on a couple internal design features and not very much on the alternator's set point. You can check a voltage regulator with an adjustable voltage power supply and a test light.
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