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Alternator going out?

vongy10

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Hi all,

I drove to work on friday, car started fine got to work no problem. Left work after about 30mins and the battery was dead. Had it jump started with a battery pack, went to get groceries and car started fine.

Went back to work the same night, started car, drove to work, no issues. Finished work after 5hrs and it's dead again. Tried to jump it and it was a no go (wouldn't crank over at all), checked the battery's indicator and it said 'take to dealer' so I assume it was toast. Borrowed a brand new battery and car started and drove fine for a day and a half.

Was going to head to work last night and car was dead again. I haven't done any electrical work on the car in about a year so AFAIK there's nothing draining the battery. So only thing left I can think of is a faulty alternator and the car has been running straight from the battery without charging which is probably what killed the previous one.
 
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accentstencil

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The best thing to do is measure the voltage at the battery with the engine running, it should be around 14.4 volts, anything much less than that means that the alternator is not charging. That it to an auto electrician to test if you don't have a multimeter.
 

vongy10

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The best thing to do is measure the voltage at the battery with the engine running, it should be around 14.4 volts, anything much less than that means that the alternator is not charging. That it to an auto electrician to test if you don't have a multimeter.
Tested the battery on charge with car off, read around 14.6v then tested with car on and it was reading around 15v, finally with the car off with not charger it's resting voltage is around 13.7v not sure how accurate my multimeter is though since the numbers kept jumping around.
 

vongy10

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Sounds like a faulty regulator in the alternator?
Yeah. I'm now thinking that too. I pulled the negative terminal off the battery while the car was running and it didn't stall so yeah I dunno.
 

vc commodore

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I'd be looking at the regulator.....With the car running, the alternator output should be 14.4 to 14.6 volts.....Jumping upto 15V to me sounds like the regulator isn't working properly, allowing too much voltage through to the battery and probably cooking it
 

Deuce

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How many km's on car/alt?
Over 200k and the brushes on slip ring might be too worn. This can sometimes appear like reg issue when in fact the reg is fine.
 

krusing

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I have repaired a few over the years, replacing the brushes on the Regulator, Replace the Bearings etc, etc,
But if you not sure how to repair them, easier to just get a change-over, then its all done for you,
And you get a warranty.
 

vongy10

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Car has 48K on it. Thanks for all the replies, may as well change it out for a new one since it's a pain to get it out especially now that I've got a snail on the side. Hoping it fixes the issue.

Also, gave the prevoius battery to my dad and he somehow got it back into the green although we haven't tested it.
 

vc commodore

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Car has 48K on it. Thanks for all the replies, may as well change it out for a new one since it's a pain to get it out especially now that I've got a snail on the side. Hoping it fixes the issue.

Also, gave the prevoius battery to my dad and he somehow got it back into the green although we haven't tested it.

Judging by this comment, yes your alternator regulator was giving you the issues.....so changing over the complete alternator/regulator would be the best solution
 
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