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Automatic Transmission - 3 Speed

1st Gear: 2.48
2nd Gear: 1.48
3rd Gear: 1.00

- Used in production GM models from 1964 thru 1990.
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76vet Alternator drain?
Guru Newb
26 Posts
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2009/2/10 1:51



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My electrics keep going dead. I don't think my alt is keeping the bat charged. Help checking? Upgrading? Fixing? Thanks!
Posted on: 2009/2/10 2:01
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Matatk Re: Alternator drain?
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Do you mean they are dying while you are driving, or while the car is sitting overnight? If while driving it could be an alternator or bad grounds. If while sitting over night or over a period of time you could have a parasitic drain (ie light staying on or some other type of electrical device drawing power from the battery). You can test for this by installing a voltmeter between the battery and cable and then pulling fuses (with car off) and seeing where there is a jump for your power drain. This will help you narrow down the circuit that is drawing power.

Your battery itself could also be bad. New/old? Have you had it tested?

Matthew
Posted on: 2009/2/10 3:23
_________________
2002 EBM convertible, Magnusson supercharger, cam, headers, etc.
1989 Corvette...RIP
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76vet Re: Alternator drain?
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Battry is good I think. 13.2 volts when put on a trickle. The alt just doesn't keep it charged. What do you think about the CS alternator's? 130 or 144 amp?
Posted on: 2009/2/10 4:57
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Matatk Re: Alternator drain?
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Being at 13.2 while on a trickle charger doesn't necessarily mean it's good.

But you still didn't say when it's dying. If while driving, that could be an indication that the alternator is bad. But remember, the alternator's job is not to charge a dead battery, so if it dies overnight, that could be your problem. You need to give us more information.

Matthew
Posted on: 2009/2/10 12:33
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2002 EBM convertible, Magnusson supercharger, cam, headers, etc.
1989 Corvette...RIP
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Durango_Boy Re: Alternator drain?
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Columbia, MO
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Quote:

Matatk wrote:
Being at 13.2 while on a trickle charger doesn't necessarily mean it's good.

But you still didn't say when it's dying. If while driving, that could be an indication that the alternator is bad. But remember, the alternator's job is not to charge a dead battery, so if it dies overnight, that could be your problem. You need to give us more information.

Matthew



I agree. Take your battery to a local parts store and have them do a full charge and a load test. It takes about an hour so drop it off and go back. Batteries can go bad but still show a normal voltage.

I would also have the alternator load tested at the parts store. It may have a bad internal regulator or diode pack.

Do you keep the car in the garage? With all the lights off at night stand in and around the car looking for light. Sometimes storage compartment lights can be stick on draining the battery and you'd never see them during the day.

Factory alarm systems have also been know to cause a problem when the relays go bad.
Posted on: 2009/2/10 13:12
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brut Re: Alternator drain?
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New Albany, IN
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I agree....start with the battery first then work your way around the charging/electrical system.
Posted on: 2009/2/10 15:40
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76vet Re: Alternator drain?
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Well...battery is good per the Zone's check. It's also only a couple months old. How do I check the alt with a meter?
Posted on: 2009/2/11 1:03
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Durango_Boy Re: Alternator drain?
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First, test the battery voltage, with the car off, at both the battery and alternator and compare the readings.

Then start the engine, and test at both the battery and alternator, again checking the readings.

What are the two sets of voltages?

Next, with everything off, disconnect the negative battery cable and put a test light between the end of the NEG cable and the NEG battery terminal. Does the test light illuminate? Go up to the alternator, and unplug the main harness plug and watch the light. Does it go out? Then remove the large gauge red wire from the battery lug, and see if the test light goes out.

If it goes out the alternator is the drain, and probably had a bad diode trio.

You can use the test light method to find any drain. Pull fuses one by one until the test light goes out. If none of the fuses do it, then using an AIM as a guide, pull every relay one by one, or courtesy light bulbs one by one, until the test light goes out.
Posted on: 2009/2/11 13:46
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76vet Re: Alternator drain?
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well, the alt shows charging. I have approxi 2500 watts of paower to my system and a set of lectric fans..could it not be keeping up? Should I ad an extra alt to the engine to keep up with the needs? or is this even possible?
Posted on: 2009/2/11 16:58
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Matatk Re: Alternator drain?
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I'd say the extra audio system is definitely a possible problem. What type of cap are you running with your amp? I went through a couple alternators in my old s10 when I had my system in there, so the alternator is suspect. Did you remove it and take it to get tested?

Matthew
Posted on: 2009/2/11 22:45
_________________
2002 EBM convertible, Magnusson supercharger, cam, headers, etc.
1989 Corvette...RIP
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76vet Re: Alternator drain?
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yes...took it down to the same Zone that checked my battry
Posted on: 2009/2/12 5:28
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Durango_Boy Re: Alternator drain?
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Columbia, MO
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Quote:

76vet wrote:
well, the alt shows charging. I have approxi 2500 watts of paower to my system and a set of lectric fans..could it not be keeping up? Should I ad an extra alt to the engine to keep up with the needs? or is this even possible?



Can you post some details about the stereo system you have? What head unit, amp, subs, speakers...model names and numbers please.

Upgrading to a higher output alternator is a good idea when you have added accessories to the system like stereos and lights and fans.

However, your problem might not be an alternator that can't keep up. You say you drive it and test the voltage and it's fine and then drained the next day? That's a drain, not a charging problem.
Posted on: 2009/2/12 14:55
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76vet Re: Alternator drain?
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i'll get all the model numbers from the manuals and post them here. the sytenm was in it when I bought it 2 years ago. What would be the best upgraded alt?
Posted on: 2009/2/12 15:25
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Durango_Boy Re: Alternator drain?
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Quote:

76vet wrote:
i'll get all the model numbers from the manuals and post them here. the sytenm was in it when I bought it 2 years ago. What would be the best upgraded alt?



That will depend greatly on the true draw of the accessories other than what was stock on the car.

What kind of electric fan is in the car? Single? Dual? OEM or after market?
Posted on: 2009/2/12 15:43
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76vet Re: Alternator drain?
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Quote:

Durango_Boy wrote:
Quote:

76vet wrote:
i'll get all the model numbers from the manuals and post them here. the sytenm was in it when I bought it 2 years ago. What would be the best upgraded alt?



That will depend greatly on the true draw of the accessories other than what was stock on the car.

What kind of electric fan is in the car? Single? Dual? OEM or after market?

not sure of the make ill check. it looks to be about a 16 inch fan
Posted on: 2009/2/12 16:24
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76vet Re: Alternator drain?
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Well...it has spal on the back of the motor. I decided to try a sc144 140amp alt and so far seams to be keeping a charge. Thanks fellas...DB can you answer my pm's?I just wanted to put these guys issues with you to rest and feel good communication with the good folks her
Posted on: 2009/2/16 2:54
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Durango_Boy Re: Alternator drain?
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Columbia, MO
2583 Posts
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What PMs? I answered all the ones you sent me from what I can tell. Did I miss one? Sorry.
Posted on: 2009/2/16 7:01
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76vet Re: Alternator drain?
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Quote:

Durango_Boy wrote:
What PMs? I answered all the ones you sent me from what I can tell. Did I miss one? Sorry.

I re sent the 2 I was taking about with the questions...tanks
Posted on: 2009/2/16 17:01
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Re: Alternator drain?
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I agree. Take your battery to a local parts store and have them do a full charge and a load test It takes about an hour so drop it off and go back. Batteries can go bad but still show a normal voltage.
Posted on: 2010/12/15 9:21
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