Battery light on.....
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
Originally Posted by MattyNJ
Just noticed my bat. light is going on when starting the truck. Also just noticed the tiny blue light for my Cobra alarm sys., blinks while armed, ( ive always thought it only did that for a minute then goes off).
Is the system (I have in my sig), supposed to blink all the time while armed? and could this be draining my batts? or is it just time for new batts? (35k miles)
Is the system (I have in my sig), supposed to blink all the time while armed? and could this be draining my batts? or is it just time for new batts? (35k miles)
If the answer to those questions is no, then you don't have a problem.
Senior User
Joined: Mar 2004
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the battery light indicates a malfunction in the charging system. read your owners manual. bench test your alternator at autozone and then buy a new one. make sure that the battery light is on when you bench test it. mine would go on and off. it tested fine with the light off but when it was on it failed. i think the regulator or something is sensitive to humidity or temperature. thats my guess anyway.
Senior User
Joined: Sep 2004
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From: Upstate NewYork
I had the same problem with my 04 F250, the light would stay on after the engine was started and would not go off until the rpms reached over 2500 then it would go off. but it kept poping on and off, did not trust it anymore so i installed a new one before it left me stranded plowing at 3am. From what i was told thay have a commen problem with the slip ring on the shaft which slips and caused low voltage. The batt. light is triggered by the charging voltage of the alt. it dose not monitor the batt. them self. It also dose not moitor amperage just voltage. I went with a 200 amp heavy duty alt. from http://www.alternatorparts.com due to the high electrical demand on my truck with, plowing and extra lights and other extral electrical equipmet. Great alt. exact fit, no problem with a few snow storms and a few months on it.
Senior User
Joined: Oct 2005
Posts: 465
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From: Nesconset NY
the slip ring wears out forming grooves down to the plastic base. At my shop we build 6g-200amp hd alternators with enhanced cooling for less then altparts, if you need contact me for more info.
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
Right. That is normal. At least, that's what mine has been doing since I bought it and I've not had any other issue concerning charging or starting.
As far as I know, if the light is off when the engine is running, there is no problem.
As far as I know, if the light is off when the engine is running, there is no problem.
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Lead Driver
Joined: Sep 2007
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From: Scio, OR
Since this thread started, I actually went out and started mine to see what it did, cause I've not paid that much attention before.
You're does exactly what mine does. When I turn on the key the battery light comes on and stays on. When I turn the key to start, it goes out briefly, comes on, and then goes out when the truck fires.
I really think this is normal. Are you experiencing any other symptoms? Slow crank or anything?
You're does exactly what mine does. When I turn on the key the battery light comes on and stays on. When I turn the key to start, it goes out briefly, comes on, and then goes out when the truck fires.
I really think this is normal. Are you experiencing any other symptoms? Slow crank or anything?
Senior User
Joined: Sep 2004
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From: Upstate NewYork
The batt. light will remain on when the key is on and the engine is not running and will go out when in engine is running pending you have a good alt. With the key on the alt. circuit is energized but no power is produced by the alt. so the light is on. As soon as the engine is started and reaches idle rpm the batt. light should go off. If it dose not then you have a faulty alt. It also acts as a test to make sure the batt. light is working and not blown out.
Senior User
Joined: Sep 2004
Posts: 432
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From: Upstate NewYork
Originally Posted by MattyNJ
the light goes on AS its starting, then goes off. So the question is, IS the altenator part of the "engine warranty" or is this NOT part of the engine!!!!
Lead Driver
Joined: Sep 2007
Posts: 8,180
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From: Scio, OR
Originally Posted by MattyNJ
yeah a very slight slow crank thats all....I was just wondering if the batts need replacement at 3yrs.
Thanks for telling me that though.
Thanks for telling me that though.
Where I am, it gets pretty cold. Below 20 degree's or so, mine cranks over pretty slow, but still starts up. When it's warm, it cranks over just fine. If that's your case, I don't think I'd worry about it.
It's kind of a matter of judgement and preference. If I had the cash, I'd stick a new set in mine just for peace of mind. But I don't so I'm not going to worry about it until next fall.
As for your alternator, it's obviously maintaining a proper charge. If it wasn't, you'd be putting a charger on it or jump starting it to get it going. I wouldn't worry about that at all.
Last edited by dchamberlain; Jan 28, 2008 at 12:11 PM.