voltage draw
Thread Starter
Burning Brakes
Joined: Nov 2006
Posts: 763
Likes: 2
From: Weston FL
voltage draw
It seems I have something draining volts/amps on my batery.
I think I have it narrowed down to the climate control unit.
If I try to start the car with the unit in an on position, the car won't start. If I leave it off, the car starts. amperage overdraw?
the dashboard volt meter reads under 11 with the unit on and only about 12.5 with the unit on. The battery is only 2-3 months old.
Today once I started the car I turned on the a/c and the volts read down to 9.5. About a mile from the house the Service ASR, the Inflt Rest, and the SVC Eng lites came on. As soon as I turned the a/c off the lites went out and the car ran fine. I drove it with the air off (not recommended in South Florida in July) for about 30 miles with no other problems.
The question is, is this a problem with the Climate Control unit or is it a bad alternator that can't keep with the draw when the climate control is turned on? I don't want to just throw parts at it so I'm hoping someone on the forum has had a similar experince to lead me down the right path.
Thanks
I think I have it narrowed down to the climate control unit.
If I try to start the car with the unit in an on position, the car won't start. If I leave it off, the car starts. amperage overdraw?
the dashboard volt meter reads under 11 with the unit on and only about 12.5 with the unit on. The battery is only 2-3 months old.
Today once I started the car I turned on the a/c and the volts read down to 9.5. About a mile from the house the Service ASR, the Inflt Rest, and the SVC Eng lites came on. As soon as I turned the a/c off the lites went out and the car ran fine. I drove it with the air off (not recommended in South Florida in July) for about 30 miles with no other problems.
The question is, is this a problem with the Climate Control unit or is it a bad alternator that can't keep with the draw when the climate control is turned on? I don't want to just throw parts at it so I'm hoping someone on the forum has had a similar experince to lead me down the right path.
Thanks
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
my vote is the voltage regulator inside the alternator is bad. Go buy a new one and install in the alternator.
cold, you should have 14.2-14.8.
once warmed up, the voltage regulator kicks the voltage down a volt to keep from cooking the battery. 13.2-13.8
If you have a rebuilt one now, your alternator may need a new stator. The mass produced rebuild shops cut the wires, then crimp the lost wire back onto the wires they cut. Those splices then heat up and cause resistance, and limit the current capacity of the stator. Then it heats up the voltage regulator, and it ceases to function properly.
Essentially, they should have un-soldered the wires instead of cut them, but that takes too much time.
I went to a wrecking yard, and got a Buick alternator that was original equipment, and changed the back half of the alternator, and BING! all problems solved.
The Buick alternator wasn't cut or spliced, and it was A-OK. I paid $35 for the Buick version.
The problem with using the Buick alternator as received, is the mounting lugs are not compatible with the Corvette brackets.
so you just use the back half of the Buick unit. Get the alternator from the same year Buick as your car.
You could probably use Buick, Olds, Pontiac, they would all work if all are 105 amp units.
You could take both alternators apart, and switch all the stuff, but why go through all that work? just switch the back half. Just pick the best brushes when reassembling, and you are good to go.
After your car works fine, THEN take the old alternator apart, get a rebuild kit for $65, and make yourself a serviceable unit that you can replace when the one on the car goes bad again.
The replacement switchout should take less than an hour, and you don't have to go anywhere.
Then rebuild the one in your hand for next time.
Buying a lifetime unit from auto zone or Checker only guarantees that you will continue to change alternators. Their units get the cutting and splicing.
Buying New is the real answer if you have the bucks for that plus everything else you have to buy.
cold, you should have 14.2-14.8.
once warmed up, the voltage regulator kicks the voltage down a volt to keep from cooking the battery. 13.2-13.8
If you have a rebuilt one now, your alternator may need a new stator. The mass produced rebuild shops cut the wires, then crimp the lost wire back onto the wires they cut. Those splices then heat up and cause resistance, and limit the current capacity of the stator. Then it heats up the voltage regulator, and it ceases to function properly.
Essentially, they should have un-soldered the wires instead of cut them, but that takes too much time.
I went to a wrecking yard, and got a Buick alternator that was original equipment, and changed the back half of the alternator, and BING! all problems solved.
The Buick alternator wasn't cut or spliced, and it was A-OK. I paid $35 for the Buick version.
The problem with using the Buick alternator as received, is the mounting lugs are not compatible with the Corvette brackets.
so you just use the back half of the Buick unit. Get the alternator from the same year Buick as your car.
You could probably use Buick, Olds, Pontiac, they would all work if all are 105 amp units.
You could take both alternators apart, and switch all the stuff, but why go through all that work? just switch the back half. Just pick the best brushes when reassembling, and you are good to go.
After your car works fine, THEN take the old alternator apart, get a rebuild kit for $65, and make yourself a serviceable unit that you can replace when the one on the car goes bad again.
The replacement switchout should take less than an hour, and you don't have to go anywhere.
Then rebuild the one in your hand for next time.
Buying a lifetime unit from auto zone or Checker only guarantees that you will continue to change alternators. Their units get the cutting and splicing.
Buying New is the real answer if you have the bucks for that plus everything else you have to buy.
Last edited by coupeguy2001; Jul 5, 2009 at 06:53 PM.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
You should notice that the red battery symbol light on the dash is on which tells you that the alternator is not charging the battery. Also, the dash voltmeter reads low when the alternator is not charging the battery and cannot be trusted. Voltage drops with the A/C on because the A/C clutch draws a lot of current. Also, your battery voltage is low and you should charge up your battery overnight at least before you troubleshoot the alternator. Engine idling, if the alternator is working, the voltage at the alternator output terminal should be about 14.7 volts, engine cold. If it is lower than 13.0 volts, you need either another alternator or yours repaired. Most auto parts stores can test your alternator if you bring it in. If the alternator output is about 14.7 volts, but the battery terminal voltage is much lower, like 12.0 to 12.9 volts, then you have a blown fusible link in the alternator output wire and it needs to be replaced. DO NOT expect the alternator to charge up a badly discharged battery, this heats the alternator and shortens its life. Also, batteries take a long time to charge up and running the engine for 15 minutes or so will not charge the battery much. Charge up the battery with a battery charger!!!!!!!!!!!!!!!!!!!!!!!
You can tell the state of charge in the battery by measuring the no load engine off battery terminal voltage. 12.0 volts and below, discharged and 12.9 volts and above, fully charged and linear in between. You can buy a decent digital voltmeter from Harbor Freight for $8, if you don't have one, buy one.
You can tell the state of charge in the battery by measuring the no load engine off battery terminal voltage. 12.0 volts and below, discharged and 12.9 volts and above, fully charged and linear in between. You can buy a decent digital voltmeter from Harbor Freight for $8, if you don't have one, buy one.
Thread Starter
Burning Brakes
Joined: Nov 2006
Posts: 763
Likes: 2
From: Weston FL
alternator was my guess also.
thanks
I got a Fluke multi-meter I use. I've been using a battery charger and that's kept the batt from dying altogether.
Thanks
thanks I'll probably order a new alt. I don't want to mess around with a rebuilt unit.
thanks
You should notice that the red battery symbol light on the dash is on which tells you that the alternator is not charging the battery. Also, the dash voltmeter reads low when the alternator is not charging the battery and cannot be trusted. Voltage drops with the A/C on because the A/C clutch draws a lot of current. Also, your battery voltage is low and you should charge up your battery overnight at least before you troubleshoot the alternator. Engine idling, if the alternator is working, the voltage at the alternator output terminal should be about 14.7 volts, engine cold. If it is lower than 13.0 volts, you need either another alternator or yours repaired. Most auto parts stores can test your alternator if you bring it in. If the alternator output is about 14.7 volts, but the battery terminal voltage is much lower, like 12.0 to 12.9 volts, then you have a blown fusible link in the alternator output wire and it needs to be replaced. DO NOT expect the alternator to charge up a badly discharged battery, this heats the alternator and shortens its life. Also, batteries take a long time to charge up and running the engine for 15 minutes or so will not charge the battery much. Charge up the battery with a battery charger!!!!!!!!!!!!!!!!!!!!!!!
You can tell the state of charge in the battery by measuring the no load engine off battery terminal voltage. 12.0 volts and below, discharged and 12.9 volts and above, fully charged and linear in between. You can buy a decent digital voltmeter from Harbor Freight for $8, if you don't have one, buy one.
You can tell the state of charge in the battery by measuring the no load engine off battery terminal voltage. 12.0 volts and below, discharged and 12.9 volts and above, fully charged and linear in between. You can buy a decent digital voltmeter from Harbor Freight for $8, if you don't have one, buy one.
Thanks
my vote is the voltage regulator inside the alternator is bad. Go buy a new one and install in the alternator.
cold, you should have 14.2-14.8.
once warmed up, the voltage regulator kicks the voltage down a volt to keep from cooking the battery. 13.2-13.8
If you have a rebuilt one now, your alternator may need a new stator. The mass produced rebuild shops cut the wires, then crimp the lost wire back onto the wires they cut. Those splices then heat up and cause resistance, and limit the current capacity of the stator. Then it heats up the voltage regulator, and it ceases to function properly.
Essentially, they should have un-soldered the wires instead of cut them, but that takes too much time.
I went to a wrecking yard, and got a Buick alternator that was original equipment, and changed the back half of the alternator, and BING! all problems solved.
The Buick alternator wasn't cut or spliced, and it was A-OK. I paid $35 for the Buick version.
The problem with using the Buick alternator as received, is the mounting lugs are not compatible with the Corvette brackets.
so you just use the back half of the Buick unit. Get the alternator from the same year Buick as your car.
You could probably use Buick, Olds, Pontiac, they would all work if all are 105 amp units.
You could take both alternators apart, and switch all the stuff, but why go through all that work? just switch the back half. Just pick the best brushes when reassembling, and you are good to go.
After your car works fine, THEN take the old alternator apart, get a rebuild kit for $65, and make yourself a serviceable unit that you can replace when the one on the car goes bad again.
The replacement switchout should take less than an hour, and you don't have to go anywhere.
Then rebuild the one in your hand for next time.
Buying a lifetime unit from auto zone or Checker only guarantees that you will continue to change alternators. Their units get the cutting and splicing.
Buying New is the real answer if you have the bucks for that plus everything else you have to buy.
cold, you should have 14.2-14.8.
once warmed up, the voltage regulator kicks the voltage down a volt to keep from cooking the battery. 13.2-13.8
If you have a rebuilt one now, your alternator may need a new stator. The mass produced rebuild shops cut the wires, then crimp the lost wire back onto the wires they cut. Those splices then heat up and cause resistance, and limit the current capacity of the stator. Then it heats up the voltage regulator, and it ceases to function properly.
Essentially, they should have un-soldered the wires instead of cut them, but that takes too much time.
I went to a wrecking yard, and got a Buick alternator that was original equipment, and changed the back half of the alternator, and BING! all problems solved.
The Buick alternator wasn't cut or spliced, and it was A-OK. I paid $35 for the Buick version.
The problem with using the Buick alternator as received, is the mounting lugs are not compatible with the Corvette brackets.
so you just use the back half of the Buick unit. Get the alternator from the same year Buick as your car.
You could probably use Buick, Olds, Pontiac, they would all work if all are 105 amp units.
You could take both alternators apart, and switch all the stuff, but why go through all that work? just switch the back half. Just pick the best brushes when reassembling, and you are good to go.
After your car works fine, THEN take the old alternator apart, get a rebuild kit for $65, and make yourself a serviceable unit that you can replace when the one on the car goes bad again.
The replacement switchout should take less than an hour, and you don't have to go anywhere.
Then rebuild the one in your hand for next time.
Buying a lifetime unit from auto zone or Checker only guarantees that you will continue to change alternators. Their units get the cutting and splicing.
Buying New is the real answer if you have the bucks for that plus everything else you have to buy.
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Thread Starter
Burning Brakes
Joined: Nov 2006
Posts: 763
Likes: 2
From: Weston FL
well I finally got around to replacing the alternator today and it was definitely the cause. It fired right up with the AC on and the volts were reading 14.7.
got a remanned from autozone for 134 with a 24 core.
got a remanned from autozone for 134 with a 24 core.
