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Battery dies every single day.

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2.7K views 5 replies 4 participants last post by  oysterboy  
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#1 ·
My battery all the sudden started dying overnight, so I replaced both of them.
The very next day... dead again. Pull them out and charged them up, both new batts tested fine as expected.
So I tested the alternator, it too tested fine.
Replaced it anyway because you can't check the diode in it. Very next day, dead again.

Performed parasitic draw test.
Nothing found. The truck draws 4 amps for 7 minutes then drops to .03. Every time I do this the truck is fine and will start the next day. I cant catch it, but as soon as I let it sit it dies.

I disconnected all aftermarket devices. No change. still .03 phantom draw.

I estimate the draw needed to do this has to be at least 4-8 constant amps for an overnight drain like this.

Any idea?
 
#3 ·
Which truck? Two in your signature, both with two batteries.
 
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#5 ·
Try pulling the ABS fuse and check for current draw. My second truck is a Chevy 1500 gasser and had the same issue. I was finally able to ID the parasitic drain source to the ABS module. I carefully separated the sealed cover and found several cold solder joints. After re-soldering, all drain issues resolved. You will need magnifying to see the cold joints.
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Also clean your frame grounds.
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#6 ·
Simple test would be to disconnect the negative cable on both batteries at the end of the day. Check the voltage one each battery with a multimeter, it should be about 12.8 - 12.6, if lower you have a battery problem. If the voltage is good then connect them and try and start the truck. If it won't start then again you have a battery problem. If it starts right up then you have a parasitic draw issue.
 
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