Alternator AMPS
Thread Starter
Pro
Joined: Jun 2004
Posts: 534
Likes: 0
From: Duncan South Carolina
St. Jude Donor '10
Alternator AMPS
I'm on my 3rd alternator in 4 years on my 90. The OEM was the first to go, then I replaced it with a reman'd from Advanced Auto and 2 months later, that one STB but they replaced it for me (they even installed it!). Well now I see that when I'm stopped at a light, headlights on, AC on and radio playing the alt gauge shows about 10, headlights dim and if turn signal is on the headlights sort of blink also. As soon as I give it some rpm's, the gauge moves up to around 12.
I am going to get it checked out today but can I replace the 105 amp with a 120 amp alternator without causing problems somewhere else later on?
I am going to get it checked out today but can I replace the 105 amp with a 120 amp alternator without causing problems somewhere else later on?
Pro
Joined: Dec 1999
Posts: 673
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From: Venetia,Pa,USA
If it will fit physicaly it will be fine. The alternator will only put out the current that the car/engine is using. For example ; if the alternator is capable of 105 amps and you are only requiring 40 that is what the alternator puts out. The reason the others fail they are too small and are always running close to or wide open. They overheat and fail.
Safety Car
Joined: Jan 2004
Posts: 3,783
Likes: 15
From: Northern California
I replied to your thread in the General section but, in general the CS130 alternators are hit and miss as far as rebuilts and a great upgrade is the CS144 120-140 amp alternators which use a larger case.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
While your car isn't likely to require more current than the original alternator, if you install a higher current alternator, you didn't also install a larger output wire to the battery and a higher rated fusible link, which in theory could overheat (wire) or blow the fusible link.
Also, charge your battery up with a battery charger. Alternators aren't meant to charge up dead batteries, they get hot and this shortens their life.
Also, charge your battery up with a battery charger. Alternators aren't meant to charge up dead batteries, they get hot and this shortens their life.
Last edited by jfb; Aug 2, 2008 at 07:52 PM.
Le Mans Master
Joined: May 2003
Posts: 5,203
Likes: 0
From: Las Vegas Nevada
I have the same problem, but I put a snap-on meter on the car and it showed that the volts on the dash were up to one full volt less than actual. That was crossed checked with another brand/type and it was the same.
I switched mine out to a Powermaster from Summit. I am comfortable with the alternator and my readout now.
I switched mine out to a Powermaster from Summit. I am comfortable with the alternator and my readout now.
Drifting
Joined: Aug 2004
Posts: 1,430
Likes: 2
If it will fit physicaly it will be fine. The alternator will only put out the current that the car/engine is using. For example ; if the alternator is capable of 105 amps and you are only requiring 40 that is what the alternator puts out. The reason the others fail they are too small and are always running close to or wide open. They overheat and fail.
Le Mans Master
Joined: Aug 2003
Posts: 9,884
Likes: 3
From: Magnolia Mississippi
St. Jude '03-'04-'05-'06-'07
Switched to 140 powermaster/chrome, and no issues with amps, large sterio setup, light upgrades, etc... but i'd research and see if you have something shorting out the alt first.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
alternator
The problem is the speed of the altenator.
The reason the volts increase when you give it gas is the pulley is too large on the alternator, causing it to drop off line at idle, and the battery voltage is what you see on the gauge. Auto electric shops can sell you a smaller pulley and install it as well.
A smaller pulley would allow the alternator to spin faster at idle, keeping up the amps and subsequently the volts.
Another way to get the alternator to put out more is to raise your idle by 500 RPM.
THis might bring the voltage producing speed up to where it is effective at idle. That's what I did. I couldn't find a smaller pulley here locally.
The reason rebuilt alternators fail is that cheap rebuilds use steel splices on the stator windings when they reassemble the alternator.
These overheat, and transfer the heat to the voltage regulator and destroy it from heat damage.
It is interesting to note as well that the voltage regulators have a thermister built in that drops the volts output by 1 volt when the alternator gets hot to keep from overheating the alternator further.
The reason the volts increase when you give it gas is the pulley is too large on the alternator, causing it to drop off line at idle, and the battery voltage is what you see on the gauge. Auto electric shops can sell you a smaller pulley and install it as well.
A smaller pulley would allow the alternator to spin faster at idle, keeping up the amps and subsequently the volts.
Another way to get the alternator to put out more is to raise your idle by 500 RPM.
THis might bring the voltage producing speed up to where it is effective at idle. That's what I did. I couldn't find a smaller pulley here locally.
The reason rebuilt alternators fail is that cheap rebuilds use steel splices on the stator windings when they reassemble the alternator.
These overheat, and transfer the heat to the voltage regulator and destroy it from heat damage.
It is interesting to note as well that the voltage regulators have a thermister built in that drops the volts output by 1 volt when the alternator gets hot to keep from overheating the alternator further.
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Safety Car
Joined: May 2002
Posts: 4,010
Likes: 26
From: Somewhere nowhere
I've gone through 5 alternators from pep-boys. Then one day I was on the road, alternator failed again, found a mom-pop auto parts store who had a locally rebuilt unit on the shelf.
It's been in there ever since.
It's obviously the rebuilder, although I had pep boys "new" fail too.
It's been in there ever since.
It's obviously the rebuilder, although I had pep boys "new" fail too.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
I'm on my 3rd alternator in 4 years on my 90. The OEM was the first to go, then I replaced it with a reman'd from Advanced Auto and 2 months later, that one STB but they replaced it for me (they even installed it!). Well now I see that when I'm stopped at a light, headlights on, AC on and radio playing the alt gauge shows about 10, headlights dim and if turn signal is on the headlights sort of blink also. As soon as I give it some rpm's, the gauge moves up to around 12.
I am going to get it checked out today but can I replace the 105 amp with a 120 amp alternator without causing problems somewhere else later on?
I am going to get it checked out today but can I replace the 105 amp with a 120 amp alternator without causing problems somewhere else later on?
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
flickering dash
your dash flickers in the garage because the auto dash dimming circuit dims in small steps and it is discernable in a less than bright garage.
Thread Starter
Pro
Joined: Jun 2004
Posts: 534
Likes: 0
From: Duncan South Carolina
St. Jude Donor '10
JFB...where would I find this fusable link to check it? Not much of a mechanic but I do have good eyesight. 
I checked all the connections on alternator and battery and all were tight.
I checked all the connections on alternator and battery and all were tight.
Le Mans Master
Joined: Jun 2006
Posts: 5,642
Likes: 5
From: One day you're a Comet...the next day you're dust... Arkansas
Motor City Reman has a 105 amp HD Maxx for your 1990 for $59,99. Go to there website and do a search. I have had mine 2 years, no problems. This is a straight bolt on.
Heel & Toe
Joined: Sep 2006
Posts: 19
Likes: 0
From: Largo Florida
Hello All,
This is an old post but I was researching alternator swaps. I have a black 86 Corvette that is eating up cs 130 alternators. I have two electric fans, ac etc. When at idle my volts drop down to 12. BTW. Do not purchase an alternator from a company on ebay called Rare Electric in Florida. I did and it lasted a month. They are wise guys and I got screwed. Anyway, I am upgrading to the CS144 alternator. The cs130's just cant handle the heat under the hood here in Florida. I can purchase a rebuilt from Advance auto for 140.00 lifetime warranty. I am also going to swap my 87 alternator too. I purchased a new cs130 for my 87 vette and it did last a few years. But now, the volts are dropping too. Its time to do both vettes. Take care.
Joe Flash man
This is an old post but I was researching alternator swaps. I have a black 86 Corvette that is eating up cs 130 alternators. I have two electric fans, ac etc. When at idle my volts drop down to 12. BTW. Do not purchase an alternator from a company on ebay called Rare Electric in Florida. I did and it lasted a month. They are wise guys and I got screwed. Anyway, I am upgrading to the CS144 alternator. The cs130's just cant handle the heat under the hood here in Florida. I can purchase a rebuilt from Advance auto for 140.00 lifetime warranty. I am also going to swap my 87 alternator too. I purchased a new cs130 for my 87 vette and it did last a few years. But now, the volts are dropping too. Its time to do both vettes. Take care.
Joe Flash man
Le Mans Master
Joined: Jan 2006
Posts: 5,620
Likes: 206
From: Orlando FL
I have never actually measured the output current from the alternator. I don’t know what is takes to run all the computers, ignition system, lights and wipers (excluding from moving seats, windows or momentary current draw). How much current is needed 99% of the time to run the car. This will give you an idea of what current capacity is really needed.
Say (i.e.) you pull 50 amps. A 100 amp alternator would be quite sufficient and a 130 amp would provide no real benefit. A higher current capability will not make it last longer unless you are close to max current rating. A good re-build or manufacturing will using quality methods and parts.
Got the car In 03, never changed the alternator and might be the original. It's hot in Orlando and doing OK so far (knock on wood).
Sounds like a nice weekend side project. I think the results will be interesting.
Say (i.e.) you pull 50 amps. A 100 amp alternator would be quite sufficient and a 130 amp would provide no real benefit. A higher current capability will not make it last longer unless you are close to max current rating. A good re-build or manufacturing will using quality methods and parts.
Got the car In 03, never changed the alternator and might be the original. It's hot in Orlando and doing OK so far (knock on wood).
Sounds like a nice weekend side project. I think the results will be interesting.
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
The fusible link is in the output wire from the alternator. They are usually close to where the alternator output wire gets connected to the battery. I am not familiar with the 90 vettes, but later C4's have a fuse block near the battery and it is possible that the fuse for the alternator is there. We need to hear from someone familiar with 90 vettes.
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
I quit counting at a dozen (at least 3 under the original warranty).
The last guy to put a Clampon on the output got 35 amps at idle.
Fans can draw 10 each, a worn blower motor can suck 20 to 25 on max.
Higher output doesn't always mean more at idle.
GM issued a Bulletin (in '96 or '98?) telling their Dealers to forget warranty reimbursement just because lights were dimming at idle.
Try www.alternatorparts.com for tutorials/more info.
The last guy who bought the "Iceberg" or dual rectifier alternator burned it up in 3 days.
The last guy to put a Clampon on the output got 35 amps at idle.
Fans can draw 10 each, a worn blower motor can suck 20 to 25 on max.
Higher output doesn't always mean more at idle.
GM issued a Bulletin (in '96 or '98?) telling their Dealers to forget warranty reimbursement just because lights were dimming at idle.
Try www.alternatorparts.com for tutorials/more info.
The last guy who bought the "Iceberg" or dual rectifier alternator burned it up in 3 days.