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Discussion Starter #1
There seems to be a problem with my starting system in my 69 Eldorado the battery seems to always be dead. i just recently changed the alternatpr with a
ac/delco and the battery with a red optima. what do u guys think the problem lies? someone said it could be the voltage regulator, but i don't want to spent more money if it doesn't help.

thanks
 

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dave383 said:
There seems to be a problem with my starting system in my 69 Eldorado the battery seems to always be dead. i just recently changed the alternatpr with a
ac/delco and the battery with a red optima. what do u guys think the problem lies? someone said it could be the voltage regulator, but i don't want to spent more money if it doesn't help.

thanks
Use your best friend in battery diagnostics. the good old voltmeter. Check the readings from the battery out of car fully charged, put it in car start it get reading, run it for awhile get reading, go nuts that will help you out w/o costing anything
 

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Discussion Starter #3
JJhomer83 said:
Use your best friend in battery diagnostics. the good old voltmeter. Check the readings from the battery out of car fully charged, put it in car start it get reading, run it for awhile get reading, go nuts that will help you out w/o costing anything
well i did that yesterday at my mechanics place and the battery was good,
but the alternator wasn't charging, he said when ever u replace the alternator
u should always replace the voltage regulator. any wisdom in the theory.
thanks
 

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1968 Cadillac Sedan deVille, 1994 Chevrolet G20
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The regulator is adjustable. You could always try that, along with taking the cover off of it and cleaning the contact points. If something is bad, then I wouldn't even bother with trying to locate and wire that stuff, just get an internally regulated alternator, either a 3-wire to keep your idiot light, or a one wire for simplicity. I would agree with replacing the regulator if alternator is bad, as the regulator relies on contact points which wear out. Cheap insurance.
 

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Discussion Starter #5
DaveSmed said:
The regulator is adjustable. You could always try that, along with taking the cover off of it and cleaning the contact points. If something is bad, then I wouldn't even bother with trying to locate and wire that stuff, just get an internally regulated alternator, either a 3-wire to keep your idiot light, or a one wire for simplicity. I would agree with replacing the regulator if alternator is bad, as the regulator relies on contact points which wear out. Cheap insurance.
Ok so i changed the voltage regulator with a ac/delco one, took the battery and the alternator to the Zone, and both the alternator and the battery are fine, so they charged the battery. later that day i was doing some resto work to the car changing the fuses and misc bulbs that are burned out. started the car just fine everything was running good, engine, lights etc. and then the next morning the whole car is dead, no power at all, no interior lights or anything the whole battery is dead. :banghead:

so what am i missing???
 

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So I am gonna state the obvious. Because its what I am good at. It sounds like something is draining the battery.

But to make sure, start that car up and take a voltmeter to the battery terminals. Should get something like more than 12. If its less than 12 then the battery isn’t getting charged but that still doesn’t fix the discharging a battery over night problem.
How old is the battery? You have any known good battery what have enough juice to start the car? Sometimes batteries won’t hold a charge very long then they get older. Just something to check.

Check the connection. It sounds stupid, but it happened to me yesterday. The connection on my 69 coupe deville isn’t tight and I tried to start the car and it all of a sudden all the light died. The tweaked the connection and everything was good again.

At this point I am out of ideas. Do you have anything other than the lights that are connected to +12 constant that doesn't have a switch on it? thats all i got
 

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Discussion Starter #7
garck said:
So I am gonna state the obvious. Because its what I am good at. It sounds like something is draining the battery.

But to make sure, start that car up and take a voltmeter to the battery terminals. Should get something like more than 12. If its less than 12 then the battery isn’t getting charged but that still doesn’t fix the discharging a battery over night problem.
How old is the battery? You have any known good battery what have enough juice to start the car? Sometimes batteries won’t hold a charge very long then they get older. Just something to check.

Check the connection. It sounds stupid, but it happened to me yesterday. The connection on my 69 coupe deville isn’t tight and I tried to start the car and it all of a sudden all the light died. The tweaked the connection and everything was good again.

At this point I am out of ideas. Do you have anything other than the lights that are connected to +12 constant that doesn't have a switch on it? thats all i got
Well the battery is a new optima red battery, and the connection is good at the battery. And not that i know of.
the only problem that i know of is that the heater, radio, antenna, do not work. the power windows, locks, power seats, wipers etc work.
can a live wire drain a full new battery in a night? :confused:
 

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The beauty of having an old car is the simplicity of the electrical system. Shut EVERYTHING off, and disconnect a battery terminal. Connect a test light between the terminal and the cable. If it lights, start pulling fuses untill it goes out. then work your way down the circut that fuse protects, looking for faulty components, or things inadvertanly left on.
 

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Discussion Starter #9
DaveSmed said:
The beauty of having an old car is the simplicity of the electrical system. Shut EVERYTHING off, and disconnect a battery terminal. Connect a test light between the terminal and the cable. If it lights, start pulling fuses untill it goes out. then work your way down the circut that fuse protects, looking for faulty components, or things inadvertanly left on.
i must be slow today cause i don't understand :confused:
 

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These things things are so much easier to explain by showing than saying. It took me a while to think through the theory behind it also.

Assuming my guess of something is draining the battery is correct, then the battery circuit is being completed. If that is the case, then a light in series at the end of the circuit (Terminal to Cable) would get lit. removing fuses is a sure way to close the circuit. So take out fuses until the light goes off. When the light goes off, you have found where the problem is. Then you can slowly figure out that fuse is connected to.

I think that’s the theory behind it. Make sure all the lights are off. Or start by pulling those fuses before you start.
 

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Discussion Starter #11
garck said:
These things things are so much easier to explain by showing than saying. It took me a while to think through the theory behind it also.

Assuming my guess of something is draining the battery is correct, then the battery circuit is being completed. If that is the case, then a light in series at the end of the circuit (Terminal to Cable) would get lit. removing fuses is a sure way to close the circuit. So take out fuses until the light goes off. When the light goes off, you have found where the problem is. Then you can slowly figure out that fuse is connected to.

I think that’s the theory behind it. Make sure all the lights are off. Or start by pulling those fuses before you start.
OK i undertand the theory, but where do i connect test light, between the battery terminial and which cable?
thanks dave
 

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Negative would be your best bet, since your supposed to remove it first anyway (and put it on last.) Leave positive connected, and reconnect the negative terminal through the test light.
 

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Discussion Starter #13
DaveSmed said:
Negative would be your best bet, since your supposed to remove it first anyway (and put it on last.) Leave positive connected, and reconnect the negative terminal through the test light.
so i connect one end of the test light to the negative battery terminal and the other end to the negative cable, and then i start pulling fuses right??
and if the light goes on its ok, but if the light doesn't come on when i pull the fuses there is a bad fuse or electrical connection, right?
 

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You got it opposite. If the light is on there's something shorting somewhere, when you take a fuse out and it goes off you found what circuit it's in.

You can also do this right from the fuse box and just take different fuses out and put the light in their place until you find it. I head this way before the battery way.
 

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Discussion Starter #15
brougham said:
You got it opposite. If the light is on there's something shorting somewhere, when you take a fuse out and it goes off you found what circuit it's in.

You can also do this right from the fuse box and just take different fuses out and put the light in their place until you find it. I head this way before the battery way.
so if i do it directly from the fuse box and i take a fuse out and the test light doesn't light when i put it where the fuse is suppose to be, what does that mean???
 

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well just checked the fuse panel with the test light and every fuse that was working meaning the test light came on when i touched it came on when the fuse was not in, so the light came on when the fuse was in and off, but some fuses the light didn't come on at all, are those the problem fuses? or is it the other way around :confused:

thanks dave
 

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Was EVERYTHING shut off when you did this check? (this includes dome light too.....) If it was, the circuts that made the light come on when you put the alligator clip on one end of the fuse socket, and touched the probe to the other are the ones causing trouble. I believe yur owners manual lists a description for what each fuse does, so you can go through and check for any lights that were left on.
 

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Discussion Starter #20
DaveSmed said:
Was EVERYTHING shut off when you did this check? (this includes dome light too.....) If it was, the circuts that made the light come on when you put the alligator clip on one end of the fuse socket, and touched the probe to the other are the ones causing trouble. I believe yur owners manual lists a description for what each fuse does, so you can go through and check for any lights that were left on.
actually i did have the dome light on, i'll check it again with everything off.

thanks
 
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