voltage drop???

today my voltmeter was reading 15 volts! i have stock electrial system, but i did add a longer battery post for my amp. but im when it is cold out it some times drops from 14.4v down to 12 when i am stopped at a stop light, then recharges again to 14.4 then somtimes moves and stays at 14.8-14.9 and rarely hits 15v..


whats the problem?? is it the alternator?

On CS-series alternators, 'normal' idle voltage can be as low as 12.5 volts, and in general, 15 volts is also within normal range... When you say you're stopped at a light, is this with a massive audio system running?

Brandon: If you added an amp, your electrical system is no longer 'stock.'

Many places (GM dealers, Goodyear, FIrestone and other auto centers, some auto parts stores) have equipment to test alternators. Probably the quickets thing to do is go to one and ask for test. You are hoping they will use a tester that can simulate heavy and variable loads, as well as poinpoint the problem, such as this one:

http://cgi.ebay.com/ebaymotors/Snap-On-Battery-Alternator-Load-Tester-YA271-USED_W0QQcmdZViewItemQQhashZitem19b90d81eaQQitemZ110478852586QQptZMotorsQ5fAutomotiveQ5fTools

...or larger. The tester should be set up to tell you if the output is sufficient, and should be able to test the diodes in teh regulator.

Albertj

When was it reading 15 volts? It will run higher after a cold start, when the most energy was used up. Did it stay there? Where is your voltmeter hooked up to?

I know its an old thread but, I can't start a new one for some odd reason. I'm in dire need of help! My engine to chassis negative post bold broke off into the chassis, and I can't for the life of me remove it! Is there another location that I could use or anyone have ANY ideas!?!? Thanks in advance.

It's a ground, you can use ANY part of the chassis. Replace the bolt, drill a hole right next to the broken one. It will ground the same.

LARRY70GS wrote:

It's a ground, you can use ANY part of the chassis.  Replace the bolt, drill a hole right next to the broken one.  It will ground the same.

Thank you that's exactly what I did.