Charging Question

[Wayne P.]

I was told that you could disconnect the negative cable while the car is running and it would not stop. I have one of those quick disconnects on the negative terminal I undid it and the engine stopped. Does this mean I am only running off my battery ? I apologize if this is a novice question.
Thanks

[Clark K.]

Re: Charging Question

Yes, it could mean that when the engine is running, that it is drawing power for the ignition system from the battery, only. What I would suspect is that your alternator is not performing enough to keep the ignition system operating when you disconnect the battery temporarily. -Clark

[William C.]

Re: Charging Question

With the battery connected and a reasonable idle, check the voltage at the battery using a high idle engine speed. Should read 13-13.5 volts or so or the charging system may need attention.

[Dick W.]

Re: Charging Question

I was told that you could disconnect the negative cable while the car is running and it would not stop. I have one of those quick disconnects on the negative terminal I undid it and the engine stopped. Does this mean I am only running off my battery ? I apologize if this is a novice question.
Thanks

If your car has an alternator, under NO circumstances would I remove a battery cable while it is running. It is possible to blow the diodes, or if it has an electronic regulator, the regulator. Does not happen all the time, but the possibility is there.

[Wayne P.]

Re: Charging Question

Thanks for the responses I will check voltage at the battery first . My fear was that I would be running the battery down over a longer trip. alternator next then regulator ?

[Terry M.]

Re: Charging Question

Thanks for the responses I will check voltage at the battery first . My fear was that I would be running the battery down over a longer trip. alternator next then regulator ?

Wayne, replacing parts as a troubleshooting method can get expensive. Why not diagnose the problem and only replace what is bad? Any shop (and it doesn't have to be a Corvette shop) worth being in business should have the tools to troubleshoot the charging system and determine what, if anything is wrong. The standard for the industry is a Sun VAT (Volt Amps Tester) 90. Any number from 40 on up will do the job, and other manufacturers make similar machines. Any of these machines in the hands of even a moron can determine if the problem is the battery, or alternator. It will take someone a grade or two above a moron the figure out if it is the voltage regulator -- and you will be handicapped by the fact that most shop employees have never seen a voltage regulator in their life, much less tried to diagnose one. For that you will need someone with gray whiskers.

If you are really desperate and can't find any shop that will test your charging system on the car you can remove the battery and have it tested at your FLAPS (Friendly Local Auto Parts Store). If that fails to find an issue, remove the alternator and take it there. You might ask on one of these trips if they can check the voltage regulator. Their equipment may not be able to do that. Most FLAPS will do these tests for free. They get their money from selling you repair parts.

Test before replacing.

[Domenic T.]

Re: Charging Question

Dick,
That's what I was told also but I have done that for years (removing the cables) without a problem as the diods are hefty in the alt.

That was the way at the dealership also, but they wouldn't mind selling a alt either.

I also used to run a alt with a wisconsin gas engine to run tools way back and I could run brush motors with no problems for long periods of time.

The alt shop that told me not to do that was trying tobow out of a bad rebuild.

I agree that the other way is a better way but I have driven miles with a battery that tested open and made it home, put another batt in and worked fine.

DOM

If your car has an alternator, under NO circumstances would I remove a battery cable while it is running. It is possible to blow the diodes, or if it has an electronic regulator, the regulator. Does not happen all the time, but the possibility is there.