Generator charging Volts low

Recently checked the generator output on my 62 car and found it to be only 12.6 at best
Tried two different regulators that I have and both are the same…what are the options?

At what engine rpms are you checking your volts? If they’re up above 1000 then it could be internal to the genny - given you’ve tried another regulator. My '62 with genny shows battery volts on the meter until +1000rpm, then it kicks in.

To test the generator, disconnect the two wires and use another wire to connect the two generator terminals together. Connect a DC voltmeter between the terminals and ground and slowly increase the engine RPMs while watching the voltmeter. This test will show you what voltage the generator is capable of.

Thats easy enough…what if it only produces 13v?

Upon further inspection i found the following
Charge at idle…12.7v at 1500…13.6v battery stand alone 12.6v
Battery is 3 1/2 years old
13.6 v is good but not great

suggestions ??

When wired as I described the generator should produce 15V at 1500 RPMs. If it never gets above 13 V then there is a problem, most likely brushes.

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Ill rig up some wiring for that thanks

Pete, if you are getting 13.6 volts at 1500 rpm’s with the voltage regulator properly connected, your system is probably okay. Usually about 13.5 to 14.5 volts is normal. Are you having a problem with your charging system? If you simply do not like it being on the “low” part of the range, I would first suggest you get used to it. If you really do not like it, you could adjust the voltage regulator, but I would discourage that. If you are having charging problems then you can continue troubleshooting.

I rigged up the shunt and got 16.5 V at the gen terminals…it seems fine…how do i get that to the batt?

You do not want 16.5 volts at the battery, you want 13.5 to 14.5 at the battery and I thought you said you have it, or was the 13.5 not at the battery?
And as I said, if you really want closer to 14.5 volts at the battery, you can take off the cover of the voltage regulator and adjust it. The procedure should be in the manual.
I asked if you have a charging problem. If you do not, I would let well enough alone. If you still want to adjust, go ahead, it is not hard.

Ive got 13.6 v at the battery…Ill leave well enough alone and replace the battery thanks all

16.5 V is way too much for a normal lead battery.
As said by Tom, for a normal lead battery, you should not go over 14.5 V.

Only silver calcium lead batteries can support around 15 V and that is the max still safe in the long term.
They were specifically designed by Varta at the time for the Jaguar XJ X350 which required a higher voltage for their electronic system.

Have you checked the GEN output with a load on the system, that is headlights or blower motor on? Also, to be more thorough, have the battery load tested. Just don’t assume it’'s bad after 3.5 years.

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Swapping the generator with an alternator is probably the best upgrade for a 3.8 S1.
I did that.
There are look alike generators that keep the same look in the engine bay and you can swap polarity to negative ground at the same time.

There appears to be an AI bot posting.

If so, I’m really curious how you come up with a Rockpals 2000W generator as a suggestion to replace the automotive generator. Really? One of these? C’mon……

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That generator puts out 12 V but only at 8 Amps, so it would probably not be enough for an E-Type. Also, I would need to have all the windows open in my 2+2 in order to be able to breathe, and I wouldn’t be able to hear the stereo. But I like the Carmin Red and Anthracite color combination.

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Clearly Jeff, it’s just a matter of making up a few brackets and maybe having to do a little bodywork on the bonnet. Cmon, let’s think outside of the box a little. :wink::joy:



Maybe add A/C at the same time?


I see the AI Bot has been removed.


Generally the charge system supplies 1volt over battery voltage and as the battery voltage rises so does the charge voltage till the regulator gets in the act and maintains something around 13.8-14.5. Health systems seem to run 14-14.2 depending on temperature and battery age in my experience