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battery warning light on start up

VPRob

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Hi All, recently my battery warning light has been coming on at the beginning of some trips and a few times during driving. When it does it also stops my CD/radio. Motor seems to crank strongly enough and lights are fine.
Does this mean my alternator is not charging while the light is on? Could it be that it just needs new brushes?
 

hi_ryder

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rambunctious

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Seeing as it also stops your CD/Radio I would be checking the earth wire from the battery to body of the car, it's a black small wire coming from the battery and screwed to the body panelling usually close to the battery.

Make sure it has a good connection to the body even if you have to remove the screw and scratch the metal where it touches the panel.
 

Alloytec

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You dont have brushes on your voltage regulator :\

Check the output of the alternator @ the back of it with the car running. should be upwards of 13volts.
 

Muke

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My first thing would be to grab a multimeter and check the voltages like Alloytec said. (If you don't have one they're pretty damn cheap & very handy). Can also check voltages across the battery and earth too, but I doubt that's the problem. Had issues with my earth wire, and the main problem was starting it. I could use jumper leads to make an earth to the block to start it, then it'd run. But it'd sometimes just stop when slowing right down (like entering servo/roundabout).
 

VPRob

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thanks guys
will follow up on those suggestions. I do have a multimeter just been too lazy to take it out to the carport. I presume there are brushes in the alternator and this is what ryder is referring to. Sounds like a quick fix but check earth connections first.
 

Jxfwsf

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can also mean the regulator is faulty, recently replaced the brushes on mine (fixed the issue of the alternator not working at all).
Now occasionally the charge light illuminated while driving so i rechecked all the wiring and handy work, noticed a strong smell of a battery over charging so grabbed the dmm and started driving around with that in the passenger seat..... the alternator was pumping out 17 volts occasionally.... was a bugger to catch and measure cause it'd only come on sometimes and wouldn't stay on long enough to diagnose properly, another reg and it's fine now.
 

DAKSTER

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You dont have brushes on your voltage regulator :\

Check the output of the alternator @ the back of it with the car running. should be upwards of 13volts.

If he doesnt have brushes on his voltage regulator that would be a problem lol... the brushes come out of the back of the regulator. +1 to Hi_Ryder and Jxw.. replace the reg pack, $50. You can buy it with or without brushes, buy the pack with brushes included. Unplug it, 2 screws, out with the old and in with the new, 2 screws, plug it back in. Too easy.

EDIT: this is the most common and likely fix for intermittent alternator light. If that doesnt work, could easily be the diodes in the alternator.. in which case you pick up a secondhand alternator for another $50 and stick your new reg pack into that.

The radio cuts out when it happens?.. thats a worry. You mean just radio or big amps? Does anything else cut out, or the engine miss or anything when this happens? If the radio cuts out, but nothing else does, when and only when the light comes on, you might be better off looking at your radio/amp wiring first..
 
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VPRob

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It's just a Kenwood tuner/CD. No extra amp. Doesn't affect the way the car runs. A couple of times the CD stops or radio goes off and I look down and see battery warning light on. Hmmm.... self installed CD player? Don't really want to chase that wiring but don't want to fry CD or car either
 

Muke

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The radio cuts out when it happens?.. thats a worry. You mean just radio or big amps? Does anything else cut out, or the engine miss or anything when this happens? If the radio cuts out, but nothing else does, when and only when the light comes on, you might be better off looking at your radio/amp wiring first..

Now that you mention that Dakster, you make a good point. If it is just the radio and nothing else (like lights dimming - going from 14v to 12v would be hard to notice from in the car though), that might be an issue. I have no idea if a short in the radio wiring would cause that light to come on. Anyone that's had alternator problems notice the radio cutting out? Also would alternator probs really cause the radio to cut out? As the battery sounds fine, I'm guessing it goes from 14v alternator charge to 12 battery drain if the alternator stops working intermittently. I'm no expert and am of the opinion that electrical devices really run on the magic blue smoke. Once you see the magic blue smoke escape, they stop working....

Good luck figuring it out, last electrical issue I had took an RACQ guy, 2 different mechanics and 3 different auto electricians before it was sorted.
 
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