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Old 07-31-2021, 03:22 PM   #1
72 Super
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Battery drain/ charging issues

Okay electrical is not my forte Lol. Here it goes. I have a 72 I picked up awhile back and it has a battery drain going on. When I first bought I thought the battery was old and on the small side (550 cranking amps)
I purchased a new AC Delco 800 CCA battery. I still had the same issue.

With my volt meter I am getting 13.6 volts with the truck running. The truck has a one wire alternator. I noticed the harness is still plugged into original external voltage regulator. Should it be? Are the one wire alternators all internally regulated?

With my volt meter set on 10A I am getting a .009 reading. I disconnected the power wire from the alt and no change.

Thanks for any advice here,
Ray
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Old 07-31-2021, 03:46 PM   #2
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Re: Battery drain/ charging issues

I would start with unpluging that external regulator.

If it is a (true) one wire alternator,

It will still show the 13.6 volts.

If it still charges PO left wiring that is no longer used.
You may be getting voltage drain from that?

Side Note: The 1 wire alternators require the engine to reach 1000 or 1200rpm before the alternator will start to charge.

Use process of elimination and unhook one thing at a time.

Night time or a dark garage is your friend.

Take your fuses out one at a time.

Then take the battery cable off and rub it against the post to see if you have an arc.

This way you can find which circuit you are dealing with.

Hope this helps.




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Old 07-31-2021, 05:33 PM   #3
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Re: Battery drain/ charging issues

Quote:
Originally Posted by Getter-Done View Post
Take your fuses out one at a time.

Then take the battery cable off and rub it against the post to see if you have an arc.

This way you can find which circuit you are dealing with.

Hope this helps.
There is a little "more proper" way to do this...& easier/quicker too.
Take a battery cable off & put a test light between the cable & the battery terminal. Isolate your connections from touching anything.
The light will light up if there is a draw...the brighter the light, the larger the draw. Pull the fuses one at a time, when the light goes out, you found the circuit with the draw. If you dont find it within the fused circuits, move on to the other items. Hope this helps, Lorne
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Old 07-31-2021, 05:39 PM   #4
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Re: Battery drain/ charging issues

Quote:
Originally Posted by HAULIN' IT View Post
There is a little "more proper" way to do this...& easier/quicker too.
Take a battery cable off & put a test light between the cable & the battery terminal. Isolate your connections from touching anything.
The light will light up if there is a draw...the brighter the light, the larger the draw. Pull the fuses one at a time, when the light goes out, you found the circuit with the draw. If you dont find it within the fused circuits, move on to the other items. Hope this helps, Lorne






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Old 07-31-2021, 07:39 PM   #5
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Re: Battery drain/ charging issues

Quote:
Originally Posted by Getter-Done View Post






.
Iíve done this numerous times and the test light does NOT light up at all. Iíve read that .01 draw is acceptable, is this this the case! I am getting and arc when I thought the battery cable to the terminal. I also disconnected the power from the alternator, no change.

The battery will drain within two days .

Thanks,
Ray
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Old 07-31-2021, 08:08 PM   #6
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Re: Battery drain/ charging issues

Member VetteVet is real good with the lingo of electrical stuff.

Maybe he will see this and chime in for the rescue

I will try to help.

Take pictures of what you do in step by step (For your own records)

It would help if you could post some here also.

So,
Step 1: You have try Test light method= No light up
Step 2: You have disconnected the Alt. = Still battery drain.

Next ( my suggestion)
Step 3:Try unplugging the external regulator

Step 4: Take the fuses out 1 by one and keep track of what you do.

There is a diagram of the wiring harness here on the forum.

If it will help I can post a Link.




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Old 07-31-2021, 08:47 PM   #7
72 Super
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Re: Battery drain/ charging issues

Quote:
Originally Posted by Getter-Done View Post
Member VetteVet is real good with the lingo of electrical stuff.

Maybe he will see this and chime in for the rescue

I will try to help.

Take pictures of what you do in step by step (For your own records)

It would help if you could post some here also.

So,
Step 1: You have try Test light method= No light up
Step 2: You have disconnected the Alt. = Still battery drain.

Next ( my suggestion)
Step 3:Try unplugging the external regulator

Step 4: Take the fuses out 1 by one and keep track of what you do.

There is a diagram of the wiring harness here on the forum.

If it will help I can post a Link.


I have the external voltage regulator unplugged. Still have the .01 draw.

When I unplugged the alternator power wire I just checked the volt meter and no change and I still got an arc at the battery terminal so I hooked the power back.

I will pull fuses one by one next.
Thanks for the tips.

Ray
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Old 07-31-2021, 09:06 PM   #8
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Re: Battery drain/ charging issues

Here is a link of the thread for colored wiring diagram.
In 1st post #322 there is a link for the wiring Dia.
The second link is page 8 Post#302 of the same thread there is a huge picture
that you have to scroll from side to side to see it all, It is Crystal Clear

1st Link: http://67-72chevytrucks.com/vboard/s...=185856&page=9

2nd link: http://67-72chevytrucks.com/vboard/s...=185856&page=8






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Old 08-07-2021, 03:55 PM   #9
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Re: Battery drain/ charging issues

While the problem is most likely in the alt. or regulator here are some other possibilities. If it has a latter model radio with a memory. It may be wired wrong with the power wire hot all the time. Check for a glove box light staying on all the time. If the horn doesn't work the wire in the column might be shorted leaving the relay engaged all the time.
George
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