Alternator working correctly?
Thread Starter
Drifting
Joined: Feb 2001
Posts: 1,603
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From: San Francisco, CA
Alternator working correctly?
I ran my battery down by leaving interior light on. Not really dead but not enough to turn the car over. Car jumped fine and I ran the car for 10 minutes with voltage guage showing +20-25 as the car ran. Turned car off and restarted fine, voltage still showed +25. I had another car that needed an alternator and began overcharging as a symptom.
So my question is : is the alternator just producing more current temporary until the battery is charged or is the alternator toast?
So my question is : is the alternator just producing more current temporary until the battery is charged or is the alternator toast?
Intermediate
Joined: Aug 2001
Posts: 36
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From: Jacksonville, FL
Re: Alternator working correctly? (R. Bruno)
You wrote voltage guage but cited a reading of +25. Voltage should be 12-14. An ammeter could display 25. Either way, you won't really know until the battery has a full charge.
Put a trickle charger on it. Check it with a hydrometer. Let it sit overnite and check it again to make sure that it is holding a charge. Sometimes with a battery that is a few years old, a near discharge is all it takes to kill it.
If your really concerned about the alternator & regulator (yours should be built in). Take it to a shop for testing or pull it and test it yourself at the parts store.
Put a trickle charger on it. Check it with a hydrometer. Let it sit overnite and check it again to make sure that it is holding a charge. Sometimes with a battery that is a few years old, a near discharge is all it takes to kill it.
If your really concerned about the alternator & regulator (yours should be built in). Take it to a shop for testing or pull it and test it yourself at the parts store.
Thread Starter
Drifting
Joined: Feb 2001
Posts: 1,603
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From: San Francisco, CA
Re: Alternator working correctly? (Bubba65)
Thanks Bubba65. I meant the guage on the dash is reading at +20-25. Prior to dead battery it read 14. My guess is that the alternator is putting out more voltage to charge the depleted battery. I just wanted to see if my thinking is correct.
Intermediate
Joined: Aug 2001
Posts: 36
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From: Jacksonville, FL
Guage reading 20-25
The alternator should not provide additional volts to charge the battery. It can if something is broke (like the voltage regulator). The battery & electrical system are built to handle 12V, no more, no less. If the alternator is pumping 20 or more volts, it would be similar to plugging your TV into the 220V stove outlet - disastrous! [img]:eek[/img] I had an electro-mechanical regulator "stick" while driving. The thing that tipped me off to a problem was the smoke from the radio/cassette player as it fried. For reasons beyond piece of mind, get it checked out.
Thread Starter
Drifting
Joined: Feb 2001
Posts: 1,603
Likes: 0
From: San Francisco, CA
Re: Guage reading 20-25 (Bubba65)
Thanks Bubba. I just changed the battery and the guage has dropped back to normal just above "0" on the guage. Looks like the bad battery was causing overcharging. Thanks for the words of caution!
