Alternator overcharging, not the regulator!, Have tried 4 regulators and still over. Options

[ken914]

My alternator keeps kicking out 16 volts! I have tried 4 regulators, I have checked the output in multiple locations and with multiple volt meters to confirm. It is definately putting out too much juice, but I don't know what to check next. The car is a '70 /6 wiht a 3.0SC. Regulator is on the panel. I don't think it is an alternator with the internal regulator, but other than having a regulator on the panel I don't know how I would know.

Any ideas of what to do to fix this?

Thanks for any help!

[J P Stein]

I had a similar problem once with my externally
regulated alternator......only I was getting 17.5 V at the battery.
That will hose up an Optima.

My D- wire connection (a splice that I had done actually) failed.
The 80SCs alternator have an internal regulator, IIRC....tho it's been some time since I've rooted around in an SC wiring diagram. What you have....God knows. I'd check your continuity and eliminate the wiring. Next, figure out WTF is in there. If it is an internal reg., its magic smoke may be missing.

[ken914]

Thanks for the hints JP. I am thinking of just punting and putting in a new alternator with an internal regulator...

[john rogers]

You didn't say what engine it is but if it is a new alt it could be the one for camper VW busses which require a different wire harness than the regular 914 harness. They have a much higher output and will cook a stock regulator and batt combo.

[plas76targa]

Ken,

I had the same problem with my stock 72 1.7 liter. Tested several Voltage Regulators, and still cranking high voltage. I checked and cleaned as many grounding locations as possible. Finally tried a new relay board and problem gone. Your problem may be different with the SC engine, but be sure to check all grounds too.

Good luck!

[lapuwali]

It pretty much has to be the regulator or the wiring to it. Any alternator will naturally put out increasing voltage as it speeds up. It's the regulator's job to prevent this from happening. Just swapping out regulators doesn't fix any wiring problems, so examine the wiring carefully between the regulator and the alternator.

[davep]

I recall someone had a problem with an alternator in a six. Same problem would also apply to a 914/4. Problem was a that a fanatic owner had cleaned and painted all of the aluminum in the area. The paint acted as an insulator and destroyed the ground circuit.

Note: the fan housing on the /4 and /6 are integral parts of the ground circuit!

[ken914]

Thanks everybody for the direction.

The regulators have three wires, what do the three wires do. I am assuming one is a ground, one is the positive side of the charging circuit and the third is a variable output to control to the alternator?

Understanding how it works will help me debug the problem.

[brp914]

been a few years, but I'll try to recollect amperes law:

when a coil of wire moves past a magnet a voltage will be generated on the wire. the faster the coil moves, and the stronger the magnet, the more voltage. this is how a generator works, and why generators are not used in cars. you can also make a magnet by wrapping a wire around a ferromagnetic core and applying a voltage to it. the more voltage you put on this coil, the stronger the magnet will become. this is the 3rd wire you refer to and is known as the "field". by modulating the voltage of field, you can account for the varying speed of the moving coil, thereby keeping its output voltage constant. the field voltage should be changing with engine speed. sorry if this too trivial for all you EE's