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hotrodding vet 10-21-2012 08:12 AM

I have been having problems with the battery not charging by the alternator I've checked both battery and alt both work but I'm run eltric fan and pump and relocated the bat to the trunk I think the alt isn't big enough to compete with the power need of the motor ,fan and pump.

69 widetrack 10-21-2012 09:44 AM

What kind of car? How many amps and volts is your alternator putting out now, not what it's rated at but, putting out? Do you have AC and what other electric options do you have on your car?

hotrodding vet 10-21-2012 10:07 AM

It's a 1978 impala no assories except power steering the volts read about 14 on alternator and it's a stock one haven't checked amps but it charges slowly but it doesn't keep it up if u get what I mean.

poncho62 10-21-2012 10:13 AM

Stock, I believe those put out 37 amps.....AC cars had a 63 amp. They also had an external regulator. Are you checking the output at the alternator or the battery?

hotrodding vet 10-21-2012 11:19 AM

I've done both I've kinda got it narrowed down to the belt is stretched or I need a bigger amp alt

69 widetrack 10-21-2012 11:30 AM


Originally Posted by hotrodding vet (Post 1601472)
I've done both I've kinda got it narrowed down to the belt is stretched or I need a bigger amp alt

If the belt is stretched, replace it...If your alternator is stock (70 amp or less) you need a bigger alternator. Check your out put at the battery, longer cables (maybe thinner cables than required) can effect the input to your battery.

If you externally charge the battery (with a plug in charger) and leave it for several days and it loses charge, you either have a bad battery or an electrical short in your vehicle.

Hope this helps

69 widetrack 10-21-2012 11:38 AM

Quick note...100 amp alternators can be picked up for relatively little expense. Remember, your alternator should put out between 13.5 and 14.5 volts...your regulator will govern that, the amount of amperage is what allows you to run a multitude of accessories. Just like your house, you can have a 20 amp circuit, it's there for you all the time, it just allows you to use more blow dryers, easy bake ovens and electric lawnmowers than a 15 amp circuit.

Hope This Helps

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