my volts are jumping!

Reply Subscribe

Thread Tools

Search this Thread

Dec 14, 2009 | 09:38 PM

ericevil

Thread Starter

6th Gear

Joined: Dec 2009

Posts: 6

Likes: 0

my volts are jumping!

my volts are running at the regular then every now and then jumping to 17 and all electrical things die but motor still going. when it goes back down a few seconds later all comes back on. any ideas? has a new altenator and battery but maybe they are bad?

Dec 14, 2009 | 10:27 PM

72LS1Vette

Safety Car

Joined: Aug 2001

Posts: 4,883

Likes: 11

From: North Easton Mass

I wouldn't suspect the battery but the voltage regulator is certainly something to look at. If it is built into the alternator I would bring it back to wherever you bought it to have it re-tested or replaced. You shouldn't see more than ~14.5 volts from a correctly operating charging system. Depending on what electronics you have in the car you can do some damage from over-voltage.

Rick B.

Dec 14, 2009 | 10:35 PM

ericevil

Thread Starter

6th Gear

Joined: Dec 2009

Posts: 6

Likes: 0

cool...thats what I was thinking. I read some other info also and some people had a bad new battery and bad new alt. so I was going to replace the voltage regulator first.
Thanks for the help!

Dec 14, 2009 | 11:01 PM

oldsarge

Race Director

Joined: Aug 2007

Posts: 10,977

Likes: 19

From: Canboro Ontario

Quote:

Originally Posted by ericevil

cool...thats what I was thinking. I read some other info also and some people had a bad new battery and bad new alt. so I was going to replace the voltage regulator first.
Thanks for the help!

I don't recall seeing what year the car was, but as mentioned above some regulators are built into the alt. and some are separate. but it does appear to be a regulator problem of some sort.

Dec 14, 2009 | 11:04 PM

ericevil

Thread Starter

6th Gear

Joined: Dec 2009

Posts: 6

Likes: 0

sorry, Its a 78 so it's built in.

Dec 15, 2009 | 12:46 PM

Darrel1

Racer

Joined: Oct 2005

Posts: 457

Likes: 1

From: Royal Oak Michigan

I had a similar issue this last summer. Had the alternator checked and they said it was fine- I checked everything. I was then told that the alternator can be bad and the stand that they are checked on may not know it. I think I was told that the regulator and/or some diodes in the alternator go bad and that causes the jumping.

Anyways- I replaced the alternator and all is good

Darrel

Dec 15, 2009 | 05:20 PM

jersey68l36

Racer

Joined: Feb 2002

Posts: 378

Likes: 19

The fact that ericevil mentioned mentioned voltmeter and not ampmeter precluded that the alternator most likely had a built-in regulator. Think by '70 or or definitely by '71, GM was using built-in alternators.

Dec 15, 2009 | 07:42 PM

stellar

Racer

Joined: Feb 2009

Posts: 427

Likes: 49

From: Pgh. Pa.

The rest of elect should run faster or brighter if reg is the problem not quit working. You have a bad connection. Not sure of wiring for that car so check at power junction, possibly at starter post.