Alternator question
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 4,711
Likes: 3
From: Middle of No where AK
Alternator question
I think my alternator is crapping out. My battery volts are dropping into the 11's while Im at a stop light. I had it check and the output amps are good but the volts seem bad.
Does anyone know if the alternator for the C5 is the same as the C6? Does my problem sound like an alternator or should I start looking somewhere else?
Does anyone know if the alternator for the C5 is the same as the C6? Does my problem sound like an alternator or should I start looking somewhere else?
Drifting
Joined: Apr 2006
Posts: 1,276
Likes: 5
From: Ambler Pa.
I think my alternator is crapping out. My battery volts are dropping into the 11's while Im at a stop light. I had it check and the output amps are good but the volts seem bad.
Does anyone know if the alternator for the C5 is the same as the C6? Does my problem sound like an alternator or should I start looking somewhere else?
Does anyone know if the alternator for the C5 is the same as the C6? Does my problem sound like an alternator or should I start looking somewhere else?
Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
I think my alternator is crapping out. My battery volts are dropping into the 11's while Im at a stop light. I had it check and the output amps are good but the volts seem bad.
Does anyone know if the alternator for the C5 is the same as the C6? Does my problem sound like an alternator or should I start looking somewhere else?
Does anyone know if the alternator for the C5 is the same as the C6? Does my problem sound like an alternator or should I start looking somewhere else?
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
Your profile shows you have an u/d pulley. That is probably your problem. The pulley isn't turning the alternator fast enough to put out the max. charge voltage.. Increasing idle speed will adjust for this. Some will say program it out, that does not take care of the problem it only hides it. Then if it does go bad you will not know because it's no longer in the program. I don't know how many rpms it needs, probably a 10% increase in idle would increase the pully speed by 10%. Maybe a tuner will help out here.
bring the idle up
Team Owner
Joined: Nov 2006
Posts: 21,136
Likes: 212
From: Long Island New York
UD pulleys arent worth it, for the minimal hp gain the tradeoff of reduced water pump flow and electrical charging its just not worth it. Unless your a serious drag guy looking to shave thousandths od seconds.
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 4,711
Likes: 3
From: Middle of No where AK
Well I didnt know the UD pulley could cause that issue. I have recently lowered my idle as well. I guess I will try to raise it some and hopefully correct the issue.
I had the alternator tested already and the volts read low. The only accessory on was the A/C and the radio. It was day time so no headlights. I dont have an aftermarket stereo so its not getting extra pull from that. Does anybody happen to know off hand how many amps and volts is normal output for the alternator? I know the battery is good too. Its brand new.
I had the alternator tested already and the volts read low. The only accessory on was the A/C and the radio. It was day time so no headlights. I dont have an aftermarket stereo so its not getting extra pull from that. Does anybody happen to know off hand how many amps and volts is normal output for the alternator? I know the battery is good too. Its brand new.
Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
Well I didnt know the UD pulley could cause that issue. I have recently lowered my idle as well. I guess I will try to raise it some and hopefully correct the issue.
I had the alternator tested already and the volts read low. The only accessory on was the A/C and the radio. It was day time so no headlights. I dont have an aftermarket stereo so its not getting extra pull from that. Does anybody happen to know off hand how many amps and volts is normal output for the alternator? I know the battery is good too. Its brand new.
I had the alternator tested already and the volts read low. The only accessory on was the A/C and the radio. It was day time so no headlights. I dont have an aftermarket stereo so its not getting extra pull from that. Does anybody happen to know off hand how many amps and volts is normal output for the alternator? I know the battery is good too. Its brand new.
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Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
Well I didnt know the UD pulley could cause that issue. I have recently lowered my idle as well. I guess I will try to raise it some and hopefully correct the issue.
I had the alternator tested already and the volts read low. The only accessory on was the A/C and the radio. It was day time so no headlights. I dont have an aftermarket stereo so its not getting extra pull from that. Does anybody happen to know off hand how many amps and volts is normal output for the alternator? I know the battery is good too. Its brand new.
I had the alternator tested already and the volts read low. The only accessory on was the A/C and the radio. It was day time so no headlights. I dont have an aftermarket stereo so its not getting extra pull from that. Does anybody happen to know off hand how many amps and volts is normal output for the alternator? I know the battery is good too. Its brand new.
it starts pulling down but when your moving its fine, the battery is good, if you have the normal size battery you can watch the gauge go down further the longer you set at idle put your foot on the gas and it will go down slower at a stop, bring the idle up too at least 750 -850
Race Director
Joined: Aug 2005
Posts: 13,592
Likes: 187
From: Hudson WI
NCM Sinkhole Donor
Thread Starter
Safety Car
Joined: Jan 2008
Posts: 4,711
Likes: 3
From: Middle of No where AK
Yes I did.
yes but your foot was on the brake, or the engine fan was on it starts pulling down but when your moving its fine, the battery is good, if you have the normal size battery you can watch the gauge go down further the longer you set at idle put your foot on the gas and it will go down slower at a stop, bring the idle up too at least 750 -850
it starts pulling down but when your moving its fine, the battery is good, if you have the normal size battery you can watch the gauge go down further the longer you set at idle put your foot on the gas and it will go down slower at a stop, bring the idle up too at least 750 -850It has manifested itself more now that it is hot. I guess the fan kicking on more and staying on could also be adding to the issue.
Race Director
Joined: Mar 2005
Posts: 11,549
Likes: 27
From: Southampton NJ
Burning Brakes
Joined: Nov 2007
Posts: 1,083
Likes: 3
From: Buena Park CA
I have the SLP Powerbond UD pulley. It's a 25% reduction in RPM. It's true that if you did not reprogram your computer to increase the idle speeds (there are two of them; in Park and in Gear) up by 25%, then you will have electrical issues with your "Alternator". If you indeed have the 25% UD, simply increase the idle speeds up to 700 RPM's, then you'll be fine.
OEM idle: ~550 RPM
Increase: 550 x .25 = 138 RPM
New idle: 550 + 138 = 688 ~ 700 RPM
Increase your computer in 50 RPM steps (if yours is like mine, you have no choice) of 150 RPM's and you'll be just fine.
OEM idle: ~550 RPM
Increase: 550 x .25 = 138 RPM
New idle: 550 + 138 = 688 ~ 700 RPM
Increase your computer in 50 RPM steps (if yours is like mine, you have no choice) of 150 RPM's and you'll be just fine.
Burning Brakes
Joined: Jan 2008
Posts: 905
Likes: 0
From: BURTON MI
I have the SLP Powerbond UD pulley. It's a 25% reduction in RPM. It's true that if you did not reprogram your computer to increase the idle speeds (there are two of them; in Park and in Gear) up by 25%, then you will have electrical issues with your "Alternator". If you indeed have the 25% UD, simply increase the idle speeds up to 700 RPM's, then you'll be fine.
OEM idle: ~550 RPM
Increase: 550 x .25 = 138 RPM
New idle: 550 + 138 = 688 ~ 700 RPM
Increase your computer in 50 RPM steps (if yours is like mine, you have no choice) of 150 RPM's and you'll be just fine.
OEM idle: ~550 RPM
Increase: 550 x .25 = 138 RPM
New idle: 550 + 138 = 688 ~ 700 RPM
Increase your computer in 50 RPM steps (if yours is like mine, you have no choice) of 150 RPM's and you'll be just fine.
Melting Slicks
Joined: Nov 2007
Posts: 2,276
Likes: 550
From: Pittsburgh PA
St. Jude Donor '10-'11-'12-'13-'14
Hot Rod Magazine tested ud pulleys some years ago, that’s exactly what they found.
Melting Slicks
Joined: Jun 2006
Posts: 2,690
Likes: 1
From: Northern Calif
I have an overdrive pulley still attached to a ho alt. The alt has bad bearings (it works but make a supecharger whine at idle) if you want it let me know. $40 plus shipping at the whole thing is yours)