dim light quiz

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03-12-2004, 05:06 PM
BennyM

dim light quiz

Lights in dash dim slightly when ignition turned off. Does this signify:

A. Bad alternator or voltage regulator?
B. Worn/dirty brushes?
C. Bad Battery?
D. Normal operation?
E. None of the above?

Sorry-- midterms week.

Thanks,
BennyM
03-12-2004, 05:16 PM
632 Regal

D

Quote:

Originally Posted by BennyM

Lights in dash dim slightly when ignition turned off. Does this signify:

A. Bad alternator or voltage regulator?
B. Worn/dirty brushes?
C. Bad Battery?
D. Normal operation?
E. None of the above?

Sorry-- midterms week.

Thanks,
BennyM
03-12-2004, 06:09 PM
Mr Project

I agree with D.

Battery output voltage is 12.6 (?) at best, alternator output voltage is 13.3-14.4, so of course the lights will be slightly brighter when running off alternator output vs. battery output.
03-12-2004, 06:35 PM
Paul in NZ

prolly normal but perhaps an indiacation

that the battery is getting old...a fully charged "12v" lead acid battery can be as high as 14v......
03-12-2004, 07:05 PM
Javier

Some times battery is OK but ...

there is poor connection on charging system or battery (+ or -). If severe, lights dim out also when running idle and go back to normal when revving up.
03-12-2004, 07:56 PM
BennyM

Battery less than 1 yr old. lights brighten w/ gas

Quote:

Originally Posted by Javier

there is poor connection on charging system or battery (+ or -). If severe, lights dim out also when running idle and go back to normal when revving up.

Yes, it does this sometimes. If I rev the engine, the headlights will get slightly brighter for a moment. They don't dim out. This is simply a bad connection?
03-12-2004, 07:58 PM
BennyM

makes sense

nt
03-13-2004, 10:38 AM
Jon K

The battery only holds a 14v charge when the alternator is feeding it... otherwise, the battery should hold 12.0 +-.5 volts when on its own... but that's rare. Even new batteries hold just below 12.0. Unlock your OBC and see what I mean. If I do Test 9 on OBC with car in Pos. 2, i get 11.98v which will slowly drop (with radio on, subs, etc) to about 11.4 until I turn it off. Even when running the car, my alternator makes abour 12.94v until i blip the throttle and then it will jump to like 13.86 - 14.09. I know these numbers by heart ever since I had alternator woes.
03-13-2004, 05:58 PM
BennyM

Done that trick b4. smilar numbers.

Quote:

Originally Posted by Jon K

The battery only holds a 14v charge when the alternator is feeding it... otherwise, the battery should hold 12.0 +-.5 volts when on its own... but that's rare. Even new batteries hold just below 12.0. Unlock your OBC and see what I mean. If I do Test 9 on OBC with car in Pos. 2, i get 11.98v which will slowly drop (with radio on, subs, etc) to about 11.4 until I turn it off. Even when running the car, my alternator makes abour 12.94v until i blip the throttle and then it will jump to like 13.86 - 14.09. I know these numbers by heart ever since I had alternator woes.

I am not super worried about it. My OBC gives me almost the same numbers. Just out of curiosity, where in the line is this measurement coming from? The battery terminals? Alternator? Some arbitrary grounding?