Voltage too high?


I recently installed a new voltage regulator on my 91 Dodge van. It is a solid state regulator and the second one I’ve tried. The alternator output is between 14.8 and 15.6 volts using a decent voltmeter and will hold steady slightly over 15 volts most of the time. This seems awfully high compared to the max of 14.4 volts the old one allowed. Is it too high? Can it be reduced someway? The first VR I used allowed surges over 18 V and I returned it immediately for the one I now have. Can I get an adjustable regulator and can I use one with the electronic ignition system and other computer controlled systems on the van?


try this site for information


The accuracy of any voltmeter is suspect if it has not been recently calibration checked against a standard traceable to NIST. There are companies that do this but it will cost more than you may care to pay. Google Instrument Calibration Service or similar wording.


I remember your first posting about this problem.

The output voltage should be no more than 15 volts. Preferably 14.8 volts as a maximum and 12.5 volts as a minimum.

There may be a problem with the second regulator also or possibly with the wiring between the regulator and the alternator. Have you checked the wiring between the two units for problems? I tend to think that regulator set point is off a little so getting another one may be in order. Can you tell me what the voltages are on the other leads to the alternator while it is running? It may help solve this trouble.

I don’t know of any adjustable regulator units available. Since the charging system is independent from the other electrical systems the only thing you need to be concerned about is the charging system is working in the correct voltage range and current capacity.


Thanks to everyone for their answers. I guess this exercise with my alternator and regulator might be for nothing since there are so many ifs to this project I will probably just go and have a rebuilt computer installed. Having had a bunch of problems with rebuilt things I have been reluctant to do so. And then there is the probllem of finding the right person or place to have the job done with confidence. After several experiences with Dodge mechanics who have just told me or wanted to do things that were so wrong even I could see them. Enough of that for now.

After reading several notes and articles about using a seperate regulator I installed mine using the positive feed from the existing blue wire in use and the existing green wire to serve as the “grounding” wire going to the regulator. That is when I had the high volt readings. Last night I read about NOT using the existing blue wire from the comp to the alt and ran a seperate new wire from the battery to the alt. The voltage holds steady at no more than 14.8, at IDLE or at HIGH RPM. I also bypassed the isolator just in case it was “disturbing” things. I will be getting a new isolator. By the way, the isolator is for the auxillary “house” battery of the camper van. Voltages taken on the hot wires connecting to the alternator are all within .5 or .6 volts. I would think this is reasonable with different resistances through the different wires and connections. Why the original blue wire (hot) makes a higher voltage output is beyond me. Maybe the route of the original positive feed through many connections the ignition switch and the computer makes the alternator charge more because the blue wire has a lower voltage.


It sounds like you have the problem licked Hambone. Good job. The voltage reading of 14.8v is great. I also think you are right on in your last sentence, in your last post. Since the voltage is lower on the blue wire than the battery voltage the regulator will try to get a higher voltage out of the alternator. This caused the error. The regulator needs to see what the battery voltage is directly, without any voltage drops in between.