Overcharging alternator and buzzing voltage regulator

[biscaynebirdie]

I keep blowing out flasher relays, oil pressure switches, and heater blower fuses in my truck, so I decided to check the voltage at the battery when at idle: 15-15.3 volts. The 1963 Chevrolet Truck Shop Manual says that 15 volts is the maximum voltage that should be had (generally, as I’m sure you all know, 12-14 is what is generally acceptable), so I have a feeling that this is probably why I keep ruining these various electrical components. I assumed it was time to purchase a new voltage regulator.

I drove down to O’Reilly and picked up a brand new regulator (made sure it was made in the USA) and decided to give it a try. With the key turned on, the generator light lit up as it should and went out when the engine started up. However, when I bumped up the RPMs just a little bit, the generator light turned on and a buzzing was heard coming from the voltage regulator. I checked the voltage while this was happening, and it was reading an astounding 16-17 volts and climbing! Not good... When I increased the RPMs a little bit more, the generator light turned off and the buzzing stopped (voltage returned to 15-15.3 volts). As I released the throttle, it buzzed again (generator light lit up as well) then stopped buzzing when at idle. I popped the cover off of the voltage regulator to check if I could see what was causing the buzz. It was, as I had assumed, the set of points that generally will be open before the engine starts and will close once running. I’ve included a picture of said points below (it’s circled in red, for ease of viewing).

I checked for good continuity in all wires in the area (voltage regulator, alternator, horn relay), as well as cleaned up all of the connectors (adding some good old dielectric grease, too). I made sure that the red wire that goes from the battery to the regulator was getting a full 12 volts, as well as checked for 12 volts on the brown wire with the key on and no volts with the key turned off. Hmm...

I’ve read that one possible culprit could be a bad diode in the alternator. Another culprit could be that my battery is at the end of its life. However, I’m not so sure about the latter since with the engine not running, the battery sends out a good 12.7-13.2 volts.

So... any ideas?

[biscaynebirdie]

This morning, I’ll try running a ground wire from the ground post on the alternator to the grounding screw at the regulator and see if it makes any difference. I currently have no wire connected to that post on my alternator (even though it should be grounded through the engine).

[biscaynebirdie]

Update: no change.

[AZKen]

I read you have an alternator with external voltage regulator. Not a generator. Either way..... Buy a Delco rebuilt 10si alternator and get rid of all that wiring, Delcotron alternator and voltage regulator. Hook up two wires and you are all fixed for about $50. Don't play around with old technology in this area.
Your battery will not last at 17+ volt charging. Free Ship May want to add This

[biscaynebirdie]

I’ve read that the one wire alternator is a major time saver. However, today I actually managed to get the original voltage regulator back in working order! 12.7 volts at idle, 13.5 volts around 1500 RPM, and goes about as high as 15 volts when I’m really giving it gas. Everything seems okay for now. If this doesn’t last, I’ll convert to the one wire alternator.

[AZKen]

I don't do one wire, just normal 2/3 wire. Hope all is good now. There is not much time savings in one wire really.

[James]

Originally Posted by AZKen

I don't do one wire, just normal 2/3 wire. Hope all is good now. There is not much time savings in one wire really.

I agree a one wire alternator is a bad choice. They can cause more problems than they're worth. Ideally the alternator should sense the voltage near the fuse block. This will minimize voltage fluctuation. Example of one wire alternator problems: Headlight going dim then back to normal when the turn signal flashes. Been there done that.

[James]

Originally Posted by biscaynebirdie

I’ve read that the one wire alternator is a major time saver. However, today I actually managed to get the original voltage regulator back in working order! 12.7 volts at idle, 13.5 volts around 1500 RPM, and goes about as high as 15 volts when I’m really giving it gas. Everything seems okay for now. If this doesn’t last, I’ll convert to the one wire alternator.

One thing that can make the voltage high is a bad connection(s). With the engine running. Take your volt meter and measure the voltage drop from the positive battery post (not the clamp) and the output stud on the alternator. You should see no more than 1/2 volt. Do the same thing on the battery negative post to the case of the alternator. You should see no more than 1/2 volt. In fact less voltage is better. I seen more alternator ground problems than anything else.

Let me know if you have a high reading (more than 1/2 volt) and on which circuit (positive or negative).

[Quigley]

I had the same problem with my 66 and put on two Delco voltage regulators and both made a buzzing sound and did not work. Bought a cheap electronic regulator from Car Quest problem solved and has worked perfectly ever since.

[biscaynebirdie]

Thank you all for your comments and advice! I’ve been spending a lot of time adjusting the contact gap and spring tension in that regulator, and I think that I have it at a point where it isn’t going to undercharge or overcharge my battery (even though I have no idea what in the **** I am doing). I went for a brief drive tonight and measured the voltage at idle once I got back. I had been running the heater blower, headlights, and turn signals during the drive but shut them off once I pulled into the driveway. At idle with no accessories on other than the running lights, my meter read 12.9 volts at the battery posts. Sound okay?

Originally Posted by James

I seen more alternator ground problems than anything else.

Funny you should mention it... I ended up running a ground wire directly from the ground post on the alternator to the ground screw on the regulator box. For some reason we hadn’t run one in the first place. Probably one reason it isn’t acting up as much.

I’ll follow your instructions and let you know what my results are. Probably going to be a day or two before I can get around to doing it.