Alternator and Charging Advice
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Le Mans Master
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From: Burlington ON
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Alternator and Charging Advice
I have been noticing during the REAL extreme heat of the day (yes we have that up here in Canada as well) when I am driving, my car's voltage meter is only around 12.6 - 12.9... In the evening when it drops out of the 90s, it will go back up to 13.4-13.6 which is where it has been at for the past 2 years. If I go for a drive while its real hot and not charging at the right voltage, sometimes when I go to restart the car it hesitates and BARELY starts. This is starting to scare me as I don't want to end up stuck anywhere. I guess I could always bump-start it, wouldnt be the first time! :D
I am just wondering whether my alternator is on its way out. Is this a common occurance that charging voltage is effected by ambient temperature?
By the way, I do have an underdrive pulley on my car so my 13.4-13.6 regular charging voltage may be a bit on the low side already but I have never had a problem before.
I am just wondering whether my alternator is on its way out. Is this a common occurance that charging voltage is effected by ambient temperature?
By the way, I do have an underdrive pulley on my car so my 13.4-13.6 regular charging voltage may be a bit on the low side already but I have never had a problem before.
Team Owner
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From: Cleveland OH
Re: Alternator and Charging Advice (MattG)
A voltage drop shows that the alternator is not able to keep up with the current draw. It may be worth your time and money to upgrade to a bigger alternator of your voltage drops below 12V ... as far as I understand, that is the magic number ... below 12 is unsafe ...
As far as temps are concerned, I dont know, but if that is the case (I hope it is) ... you are fine ... as long as you are above 12V ...
As far as temps are concerned, I dont know, but if that is the case (I hope it is) ... you are fine ... as long as you are above 12V ...
Le Mans Master
Joined: Oct 1999
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From: Tucson AZ
Re: Alternator and Charging Advice (MattG)
How old is your battery Matt? The underdrive pulley doesn't help; the alternator needs to work harder/longer to do the same job, and it is hard to keep up when the fans are running often. I had the same thing happen to me several years ago in Bloomington. My car acted like yours, but we made it down there with no problem. We lined up for the road tour and quess what..... everyone started and "toured" except us; car would not start and battery needed a jump/charge to get us going. I returned to OEM pulleys and never had a problem again. :rolleyes: :)
Thread Starter
Le Mans Master
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From: Burlington ON
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Re: Alternator and Charging Advice (carpe dm)
I don't have any extra electrical accessories on my car other than the PIAA foglights so I can't see why I would need a more powerful alternator.. I could understand this if I had a big aftermarket stereo or something like that...
The battery in my car is a AC DELCO :U that was put in about 16 months ago after the original battery died on me at the track. Unfortunately I was nowhere near a place to buy a good Optima so I had to settle for an AC DELCO or I wouldnt have gotten home.. The battery hasnt lead me to belive it is the problem at all.. What is a sure tell way to know if it is the alternator or battery that is causing the problem? Load test the battery?
As for the underdrive pulley, I haven't ever had an issue with in in the 14 months it has been on my car, but I do understand that it doesnt spin the alternator quite as fast..
hmmmmmmmm...........
The battery in my car is a AC DELCO :U that was put in about 16 months ago after the original battery died on me at the track. Unfortunately I was nowhere near a place to buy a good Optima so I had to settle for an AC DELCO or I wouldnt have gotten home.. The battery hasnt lead me to belive it is the problem at all.. What is a sure tell way to know if it is the alternator or battery that is causing the problem? Load test the battery?
As for the underdrive pulley, I haven't ever had an issue with in in the 14 months it has been on my car, but I do understand that it doesnt spin the alternator quite as fast..
hmmmmmmmm...........
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Re: Alternator and Charging Advice (MattG)
To answer the question about voltage output versus temperature, yes the regulated output voltage of the alternator will drop with temperature. At 12.9V, I wouldn't be too worried, I've seen mine get that low on hot days sitting in traffic. At 12.6, you are right to be concerned. You may want to check the voltage right at the battery terminals with a voltmeter to correlate to the voltage the DIC is giving you.
Team Owner
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From: Cincinnati, Oh USA
Re: Alternator and Charging Advice (MattG)
Your alternator is normal. The alternator has a negative temperature coefficient, this is, its output voltage drops with increasing alternator temperature. Normally the alternator puts out 14.3-14.7 volts cold and it drops to 13.3 hot. In your case with increased ambient temperature it drops a little bit further. A lead acid battery is considered discharged when its terminal voltage reaches 12.0. Since your alternator gets to 12.6, it should keep your battery up far enough for starting.
Melting Slicks
Joined: Oct 2001
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From: Panama City Beach FL
Re: Alternator and Charging Advice (jfb)
For what it's worth, pick up August edition of Corvette Fever. In it, they show how to test your alternator.
Also, check that you have a good, clean contact between the cables and the terminals on the battery.
Also, check that you have a good, clean contact between the cables and the terminals on the battery.
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From: Cleveland OH
Re: Alternator and Charging Advice (luvinc5)
You might want to look into a new battery ... then upgrade the wiring in the egine compartment to 4ga ... most guys do this when they get a stereo installed ... it helps becuase the current is able to flow easier ... then in the worst case ... get a new alternator ... a 170Amp model costs $200 approx at http://www.alternatorparts.com ... the combination of heat and the pulley will drop the 170 down to a level which is more than enough ...
I think that the alternator is the last resort ... 12.6 is probably safe ... I also assume that the 436ci engine gets hotter than a normal 350ci ... and that might be heating the area near the alternator ...
[Modified by NewVetteLover, 11:43 PM 7/5/2002]
I think that the alternator is the last resort ... 12.6 is probably safe ... I also assume that the 436ci engine gets hotter than a normal 350ci ... and that might be heating the area near the alternator ...
[Modified by NewVetteLover, 11:43 PM 7/5/2002]
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Le Mans Master
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Re: Alternator and Charging Advice (MattG)
The easiest and cheapest method of fixing your problem is to buy an overdrive alternator pulley.
ASP makes one and the suggested price is $29.95 the part number is either ASP540120 or ASP540084 , not too sure, you would have to call them and ask. The pulley is a 33% overdrive pulley and will fix all of your low rpm charging problems.
[Modified by pkmoose, 12:33 AM 7/6/2002]
ASP makes one and the suggested price is $29.95 the part number is either ASP540120 or ASP540084 , not too sure, you would have to call them and ask. The pulley is a 33% overdrive pulley and will fix all of your low rpm charging problems.
[Modified by pkmoose, 12:33 AM 7/6/2002]
Le Mans Master
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From: Chandler AZ
Re: Alternator and Charging Advice (MattG)
Matt,
Before shelling for a battery and/or altenator my advice would be to take both to an auto parts store and have them load tested. This should tell you which one is marginal. If they are both OK then I would say that perhaps the underdrive setup is affecting ability of altenator to keep up with charging.
Down here in Arizona it is not uncommon, for me at least, to have any of my vehicles start out with 14+ volts then taper off to around 13 or so after the car has been running in the HOT AZZ desert heat. But the hard starting leads me to believe that you have a marginal cell in your battery or the underdrive setup... so thats what I'll guess:)
[Modified by billreid1@***.net, 9:44 AM 7/6/2002]
Before shelling for a battery and/or altenator my advice would be to take both to an auto parts store and have them load tested. This should tell you which one is marginal. If they are both OK then I would say that perhaps the underdrive setup is affecting ability of altenator to keep up with charging.
Down here in Arizona it is not uncommon, for me at least, to have any of my vehicles start out with 14+ volts then taper off to around 13 or so after the car has been running in the HOT AZZ desert heat. But the hard starting leads me to believe that you have a marginal cell in your battery or the underdrive setup... so thats what I'll guess:)
[Modified by billreid1@***.net, 9:44 AM 7/6/2002]
Thread Starter
Le Mans Master
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From: Burlington ON
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Re: Alternator and Charging Advice (billreid1@***.net)
Thanks for the help guys.. I am going to get the alternator and battery tested out and see if anything is wrong or whether it is just the heat.
