Voltage regulator output

[Lawrence S.]

What should voltage regulator output be from the VR when the engine is spinning 3000 rpms. 67 L-36, no lights on, non a/c car.

What is the safe maximum output from a original style VR?

Thanks

Lawrence

[Richard M.]

Re: Voltage regulator output

I'd say anything over 14 volts could compromise your electrics. Especially if you have any Digital accessories like non-stock radio, CD player, Ipod, etc.

What are you reading? 13 to 13.8 is what I like to see when the alternator is spinning, all based on battery static voltage.

Rich

[Lawrence S.]

Re: Voltage regulator output

I have several readings that I have taken with three different VR's
Wells VR from Auto Zone, non point style
14.49 volts at 1700 RPM
14.14 volts at 1,000 RPM
Both above with a cold to warm engine

Hot engine
14.19 volts at 1000 rpm

cold engine

14.5 volts at 1100 rpm

New Delco Remy style with points style
15.54 volts at 1500 RPM
13.5 volts at 600 RPM
15.3 volts at 850 RPM

Original Delco Remy VR that came with the car when new
14.45 volts at 1000 RPM
13.45 volts at 500 RPM
14.25 volts at 650 RPM

16.5 volts at 3500 RPM while sitting in the drive way

I did not get any readings at 3500 RPM with the other two VR's.

I have been running the new Delco Remy point style with no problems. I wanted to run the original so I decided to do these tests. I wanted to compare the non point style parts store VR also so I took those readings.

Thoughts?

[Richard M.]

Re: Voltage regulator output

Lawrence, Some of those seem very high to me, in particular the 16.5 v using the original DR unit. Where are you probing? If directly at the alternator, they'll be high there as it's before any voltage drops through the electrical system to the loads. Did you also measure at the battery post, and inside the cabin?

edit......I wonder if your alternator has a problem. What is it's spec?

Rich

[Lawrence S.]

Re: Voltage regulator output

All readings at the battery post.

The alternator has been freshly rebuilt...not saying it is perfect but that is the case. I bought it from a vendor...can't recall his name at Kissimmee in 2012.

I agree the 16.5 volts seems high too. I may just flip out to the newer DR points style.

[Dan D.]

Re: Voltage regulator output

Battery voltage should be at or near 14.4V with a fully charged battery and the alternator spinning. If you are reading 13.x volts it could be the battery is not fully charged and is still absorbing current. Measure it again after the batt has had time to charge up. If it does not come up any more then the regulator has failed and the battery will never see full charge, and will have low cranking reserve.

Battery voltage will drop to around 12.6v when the engine is shut off.

16.5v is way too high and will cook the battery and may damage digital electronics, Definitely will blow out Halogen lamps in short order. The regular has failed.

-Dan-

[Michael H.]

Re: Voltage regulator output

I adjusted mine to 14.2 volts and I've had not problems at all for the last 5 years.

Mike

[Gene M.]

Re: Voltage regulator output

For normal driving I would use the solid state unit. On the show field the original is my choice. I have run into points type regulators that will just not set up correctly at anything over 2000 RPM. Always too high voltage output. I gave up on them.

I need to have Dan Dillingham check them out..........!

[Duke W.]

Re: Voltage regulator output

What should voltage regulator output be from the VR when the engine is spinning 3000 rpms. 67 L-36, no lights on, non a/c car.

What is the safe maximum output from a original style VR?

Thanks

Lawrence

You didn't say what type of regulator your car has. If it's the base OE mechanical type there is an adjustment procedure in the CSM. The proper range is 13.5-14.5 volts, hot, and the regulator should maintain this range at most loads at any engine RPM.

The one exeption is that voltage may drop below this range at idle with a very heavy electrical load, and one thing that places a very high load on the alternator is a signficantly discharged battery.

I usually measure system voltage at the battery posts. A fully charged battery should measure about 12.6v at 80 degrees F and the above stated range with the engine running at any speed and load other than the exception stated.

System voltage greater than fully charged battery voltage is what charges and keeps the battery fully charged while the engine is running, but excess charging voltage can cause the electrolyte to spill out of the cell vents, excess hydrogen production, which can cause an explosion, and eventually "cook" the battery. So excess charging voltage should be tended to immediately!

Duke

[Richard M.]

Re: Voltage regulator output

You didn't say what type of regulator your car has.

Duke

Duke, You missed his post #3. He tried every type. Highest reading is 16.5v with his original unit. Way too much.

I agree, it could cook the battery, and more. Happened to my '59 years ago when the regulator points stuck closed. Fried the armature in the generator and the generator harness.

[Duke W.]

Re: Voltage regulator output

In that era I believe a transistor regulator was included on some models based on options, but he didn't state if the one that was on the car was mechanical or transistor.

Most solid state regulators cannot be adjusted, but the OE mechanical type can, and I assume that a current mechanical type can be adjusted, too.

Duke

[Richard M.]

Re: Voltage regulator output

IIRC, my '64 Shop Manual may have reference to a solid state VR, or maybe it was the '67 Manual, I forget.

[Lawrence S.]

Re: Voltage regulator output

I have the standard ignition VR in the car. I took it out and put back in the repo mechanical type that I have been using for months with no trouble. I will check the high rpm voltage though so I have that reading.

Previously, I had read the section in the CSM about adjusting the VR. Seems complicated? I need to take a closer look at this. I would like to learn to do this.

Thanks guys,

Lawrence

[Richard M.]

Re: Voltage regulator output

Lawrence, I just checked the Voltage Setting spec for the VR, and according to the ST-34 1964 CSM, it's 13.5v to 14.4v @ 125* F. I'd set it at 13.8v.

BTW, the '64 offered the solid state VR and the mechanical double contact VR. I'm uncertain what determined which type was used for what application in Corvettes. The '67 CSM mentions the double contact type(non SS) with the 63 amp alternator when used with Air Conditioning.

However, they both contain adjustable output voltage.

'64 Mechanical:
P3090002.jpg

'64 Solid State:
P3090001.jpg

My '67 CSM shows pics of the SS type, but I've never seen this type on a Corvette.

P1010003.jpg P1010004.jpg