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Parasitic load


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I have an '06 with the big alternator. The battery is 1 year old. I didn't drive the truck for a while and the battery died, ok no sweat, I put the charger on it and zip, notta. So I did it 2 more times and zip, notta; I measured 1.3 volts! The 3rd time I charged it I disconnected the battery and it took a charge. had the system tested at the local A/P store and everything passed with flying colors. Backing up, when I connected the ground to the battery I got a pretty health arc, now I know there is parasitic voltage to run the clock and such but is it so much that I should see an arc in day light when connecting that battery? So my question is how do test for the parasitic voltage and how much should it be? I have the tow pk, the big alternator, A/C, pwr dl,windows, pwr sun roof....it's loaded....

Edited by dna9656
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If you have a multimeter that measures amps and milliamps, the procedure to test for a draw is:

1) Run the truck for a few minutes so that the alternator has a chance to fully top off the battery

2) Turn off the truck, take the key out, pop the hood, shut all the doors and lock the truck

3) Wait a few minutes

4) Turn on your multimeter to the highest capacity current measurement it has

5) Loosen the negative terminal of the battery (being very careful not to disconnect it fully)
6) Touch one multimeter probe to the negative cable, and one to the negative terminal of the battery

7) Keeping the probes in tight contact, remove the cable from the battery

😎 If the multimeter reads 0, move it to the next most sensitive setting. Repeat until on the milliamps setting.

9) A normal draw would be in the ballpark of 50 milliamps or so. If you have significantly more than that then you should have an assistant remove fuses one at a time while you hold the probes and watch the meter. 

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Thank you very much! I will print this out and put it in my file. After charging the battery in a disconnected state it charged right up like the 11 month old battery is is. Took to Auto zone and they tested it, all seems well. I'm thinking the battery was just too discharged to charge while still connected to the truck. I measured the voltage at the battery at 1.3VDC that's pretty low.... It started just fine yesterday and today.

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Had this happen to me once.  Had to take the battery out and hook up to 50 amp charge and run it for 10-15 minutes at time with a rest and repeat for several hours before it would take a charge again.  When that happened, the battery was past its useful life and we got another year out of it using a battery tender afterwards.

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Interesting! Ya know, when you buy a battery most anywhere the store keeps a record for warranty purposes; except Wal Mart of course. There you get a tiny receipt (much smaller than their usual receipt) designed to get misplaced or lost because without your Wal Mart  receipt you have no way to make them perform on the warranty.

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2 hours ago, dna9656 said:

Interesting! Ya know, when you buy a battery most anywhere the store keeps a record for warranty purposes; except Wal Mart of course. There you get a tiny receipt (much smaller than their usual receipt) designed to get misplaced or lost because without your Wal Mart  receipt you have no way to make them perform on the warranty.

Now though if you have a walmart account and app.  Have that card you use linked in your account it automatically saves all of your purchases when you use that card, you can even start a return from the app in that purchase.  Just don't pay cash as there would be no record.

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I had-have two vehicles with aftermarket alarms. Once the battery gets a little age on it if they aren’t driven every two weeks the battery will need a charge before they’ll start. I can’t recall any other of my vehicles sitting that long that didn’t have aftermarket alarms to compare. 

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