Parasitic drain help... - Impala Tech
Electrical & Wiring Troubleshooting electrical problems

 
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post #1 of 8 (permalink) Old 08-03-2013, 10:26 PM Thread Starter
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Parasitic drain help...

Seeking assistance on a stubborn issue. I'm chasing a bizarre problem in which I can't draw enough power from the battery to start the engine. If I hook up to a charger I can start the car. The battery tests good, the alternator tests good. I thought parasitic drain, but not too sure about that now. If I run the car for half an hour, and disconnect the battery after shutting it off (should be fully charged battery), the car will still not start if I wait 30 more minutes. Anyone seen this before? Thanks in advance!


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post #2 of 8 (permalink) Old 08-04-2013, 01:27 AM
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Sounds like you don't have a good enough ground to the motor or need to replace both battery cables with thicker gauge.

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post #3 of 8 (permalink) Old 08-04-2013, 03:29 AM Thread Starter
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Cool. Thanks for the response. I will try upgrading both positive and negative with new wires. It's 0 gauge, so I don't think it's the thickness. After that i suppose i should consider a new engine wire harness as it looks like its seen better days. Appreciate the tip...


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post #4 of 8 (permalink) Old 08-04-2013, 08:36 AM
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Make sure your starter bolts are tight
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post #5 of 8 (permalink) Old 08-04-2013, 09:00 AM
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If you have a test light connect it between the pos post and the pos battery cable with everything in the car shut off. If it lights up bright, you have a draw. Pull fuses and unplug electrical items until the light goes out. I have found several alternators with internal shorts killing batterys.
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post #6 of 8 (permalink) Old 08-04-2013, 09:05 AM
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Your car came with one gage wire battery cables. If you have replaced them with new cables from your local discount auto parts store they are probably only four gage wire as that is what the factory is now using to cut costs. The heavier gauge (smaller number) is what you want. If you can still find six volt starter cables and ground they are double zero gage wire; that is the same size as is used for welding cables when you are welding a hundred feet or so from the welder.

Also you can not have any paint on the block or on the top of the starter motor where they bolt together. This is the most common source of a bad ground, plastic insulating paint. There should be only bare metal at the point of contact between the two.

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post #7 of 8 (permalink) Old 08-04-2013, 12:41 PM
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I think you have a bad battery. A battery can show good surface charge, but not be able to deliver under load. Have it load tested, not just checked for voltage.

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post #8 of 8 (permalink) Old 08-04-2013, 10:26 PM Thread Starter
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Hi all. Thanks for the troubleshooting tips. I ended up picking up 2 gauge leads for everything and sanding the block ground really well. I was running 4 gauge before and there was definitely some corrosion going on. It's amazing what a good set of wires does.


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