Overcharging alternator and buzzing voltage regulator
 

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?

Re: Overcharging alternator and buzzing voltage regulator
 

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).

Re: Overcharging alternator and buzzing voltage regulator
 

Update: no change.

Re: Overcharging alternator and buzzing voltage regulator
 

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

Re: Overcharging alternator and buzzing voltage regulator
 

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.

Re: Overcharging alternator and buzzing voltage regulator
 

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.

Re: Overcharging alternator and buzzing voltage regulator
 

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.

Re: Overcharging alternator and buzzing voltage regulator
 

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).

Re: Overcharging alternator and buzzing voltage regulator
 

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.

Re: Overcharging alternator and buzzing voltage regulator
 

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?
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.

Re: Overcharging alternator and buzzing voltage regulator
 

I’m almost wondering if they have the wiring mixed up in those reproduction regulators... It’s the generator field contact point that is buzzing, but this contact shouldn’t buzz at all. It should simply open when the engine is off, and close when the engine is started. I would have tried experimenting with mixing the wires around, but didn’t want to deem it non-returnable if something burned up.

Re: Overcharging alternator and buzzing voltage regulator
 

So... I checked the voltage from the positive battery post to the alternator output stud:0.2 volts. No volts read on the negative end.

However, I’m currently letting the truck run at idle at operating temp with headlights, high beams, and heater blower running. The voltage is currently at 12.3 and falling slowly... So turns out I don’t have something adjusted right in the regulator.

What’s odd is that when I checked the voltage right after starting the engine, it was at 13.5 volts (12.7 volts before starting the engine). My dad is telling me that temperature is the cause of this, but it’s only 50 degrees outside. Shouldn’t the alternator be sending out at least 13.5 volts regardless of accessories and temperature?

I’m seriously considering converting to a 10-SI and calling it quits on this wild goose chase.

Re: Overcharging alternator and buzzing voltage regulator
 

I used this link from the Jolly Page to update to an alternator. The Mad Electrical has lots of information for the update and remote sensing.

http://6066gmcguy.com/charging.html

http://www.madelectrical.com/electri...hreewire.shtml

Re: Overcharging alternator and buzzing voltage regulator
 

Voltage drop is great.

With the engine idling and the headlights on high and blower running, your voltage is doing what it is suppose to do. If you was to raise your rpm the voltage will come back up. Just remember you are normally driving so the engine rpm is higher all the time and the voltage will be where it needs to be. If you have ever seen a amps curve for an alternator you will notice the higher the rpm the more amps output you will have. Proper voltage setting is with everything turn off with a fast idle (approx. 1000 rpm).

Installing a 10SI alternator will provide more amps at idle. Which is something I am planning on doing when I repair the under the dash air conditioner.

Re: Overcharging alternator and buzzing voltage regulator
 

I wasn’t aware of this. If the truck just stayed at idle all of the time, I suppose it wouldn’t really be a truck! :)

I checked the voltages at various RPMs today once I got home from work. This was done with no accessories running. Ambient temperature under the hood was 80F.

Idle: 12.9 volts
1500 RPM: 13.7-13.8 volts
2500 RPM: 14.7-14.8 volts

According to the 1963 Chevrolet Truck Shop Manual, this is right within specification.