Low or No Charging

[Christopher R.]

My 2268 (35 amp) Pirkle rebuilt generator worked fine with an aftermarket voltage regulator (VR) until I replaced that VR with a Delco one for judging. Now the ammeter shows a constant slight discharge at all electrical loads and at all engine speeds. I did polarize the system when I swapped VRs. While running, the ammeter shows a slight discharge. If I turn on the headlights, the ammeter will dip more into the "-" zone, but then recover and go back to showing the same slight discharge as before. Of course, I suspect the VR.

But before I replace the VR, I'd like to understand this condition more.

Has anybody heard of this condition? It seems that the generator is generating and the VR is regulating. Just that the VR is regulating incorrectly.

[John F.]

Re: Low or No Charging

I think the shop manual has a section on checking/setting a VR. Have never tried it myself. Some of the old electrical shops still mess with them.

[Duke W.]

Re: Low or No Charging

The old ammeters are not very accurate. They are really a voltmeter that uses the slight voltage difference at two points in the system as a surrogate for charge/discharge.

Use an accurate voltmeter to check system voltage at the battery posts with the engine idling. Start with no load and then add load such as headlights and blower motor. With minimum load, voltage should be between 13.5 and 14.5 volts. As load increases at idle it may drop below 13.5.

If system voltage is okay, the problem may be in the ammeter connection between the two reference voltage points - like too high resistance at the connections.

If system voltage is not okay, the regulator probably needs adjustment.

ST-12 should have an electrical schematic and regulator adjusting procedure as does the 1963 Corvette Shop Manual.

Duke

[Gary C.]

Re: Low or No Charging

Chris,

Would suspect the new voltage regulator "relay gaps" might need to be adjusted.

Regulator air gap information is in the back of the ST12 Corvette Service Guide.

Google link

http://www.42fordgpw.com/voltage.html

Have a Delco Remy Service Bulletin on adjusting regulators - send me your email address & I'll email it to you as it's too large of a file to post.


Gary
....

[John H.]

Re: Low or No Charging

The old ammeters are not very accurate. They are really a voltmeter that uses the slight voltage difference at two points in the system as a surrogate for charge/discharge.

Duke -

That's true for the midyears, but not for C1's; the C1's have a true ammeter that's directly in series between the battery and all the loads. That changed in 1963 to the dual-sensing galvanometer arrangement that was used until they went to voltmeters.

[Christopher R.]

Re: Low or No Charging

Thank you gentlemen for your advice. Thank you Gary for the Google link. I already have the Delco Service Bulletin. With that, the ST-12, and your link, I hope to be able to figure it out.