Battery Light comes on when idling

ADU

MEMBER
MAZDA

Its been a couple of weeks since this problem started.
I see the battery light coming ON when Im idling at a traffic signal.
It happens only when I drive back home at night and doesnt happen in the morning.
I noticed that if I switch off the headlight when I am idling at the signal and use them only when the car is running, the battery light does NOT come on.
I have also tried using the radio for my entire ride to office and it doesnt cause the problem.
Both the alternator and the belt are just 1 year old.
The battery is 5 months old.

Could it be a short in the headlight circuitry or is it a problem with the battery?

Could you please suggest what could be the problem and how do I track the problem? Also, can I fix the problem, if so how can I do it?

3 Replies

BRUCE HUNT

MECHANIC
3,753 POSTS

You may not appreciate the answer but I highly doubt the alternator you got was properly rebuilt. I would take it to someplace and have it checked. The symptoms you describe point to the alternator.

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Monday, November 27th, 2006 AT 8:13 PM

ADU

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I do appreciate the response from you.
I got the car charging system checked at Pep Boys.
The report showed that the Battery was nearing its useful life and had to be replaced soon. I have replaced it.

It also gave a bar graph of the alternator performance and the details are as below
IDL no load : LOW (significantly below the min voltage)
IDL with load : LOW (way below the minimum voltage)
RUN no load : OK (Just above the minimum voltage)
RUN with load: LOW (Just below the minimum voltage)

My questions are:

1) From the above graph details would you be able to tell me if it is necessary to replace the entire Alternator, or is it some part in the alternator which needs to be replaced?

2) What are the possible reasons for the alternator going faulty?

3) Normally how long do alternators last?
Mine was an expensive one and I think it couldv been purchased from an authorised dealer from the previous owner.

Thanks again for the response Hunt.
Hope to hear from you again soon.

Thanks
adu

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Monday, December 4th, 2006 AT 5:09 PM

ADU

MEMBER
15 POSTS

I had the alternator replaced and the problem seems to be fixed now.

The problem was with the alternator.

Thanks a lot for the responses and cheers to Hunt.

Thanks,
Adu

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Wednesday, December 20th, 2006 AT 11:02 AM