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Old 02-13-2020, 01:11 PM   #1 (permalink)
SRR
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Voltage in old truck with batteries disconnected

I don't drive my truck very often so the batteries are a pain to maintain. I recently got a new set under warranty so I decided to go ahead and install manual disconnect switches on them. I did that yesterday. In the process, I noticed the truck itself has a charge of 0.15 volts on it. I checked it again this morning and it still has 0.13 volts.

Where does this voltage come from? I assume it must be related to the IOD that sucks the power out of my batteries in a few weeks. Is there some sort of rechargeable battery in the radio or computer?

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Old 02-13-2020, 01:19 PM   #2 (permalink)
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Thread relocated over to the 6.5L section for better views and responses to your issue



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Old 02-13-2020, 01:58 PM   #3 (permalink)
SRR
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Thank you. This is where I wanted to post it but wasn't sure about appropriateness since my question really isn't about an engine.
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'94 K3500 Silverado DRW long bed crew cab 4X4 with most of the options
Bought on 3/23/11. Current mileage 161,805
It came with new 6.5L TD Goodwrench crate motor dealer installed at 99k miles and 4L80-E trans rebuild at 135k miles
G80 4.10 rear, 225/75 16 tires
New Stanadyne FSD on 3x6x1 aluminum heat sink, remote mounted above and behind the bumper.
Heath Turbo Master, Hayden SD fan clutch & trans cooler
Diamond Eye 4" exhaust, GlowShift diesel combo gauge. Analog EGT, Digital Boost & Trans Temp
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Old 02-13-2020, 03:53 PM   #4 (permalink)
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There are capacitors in the radio, PCM, and other electrical. They are like little batteries. They will hold a small charge and give it up slowly over time.
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Old 02-13-2020, 03:58 PM   #5 (permalink)
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Are you measuring this with the batteries completely removed or with the disconnect installed and switched off?

I will take a guess and say that it could be from the larger capacitors in the radio?

If it really bothered you you could go about it a few different ways, easiest would be to hook up the dvm where you can see it and start pulling fuses until it disappears.
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Old 02-13-2020, 08:05 PM   #6 (permalink)
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Radiator is acting as a battery. Antifreeze needs changing.
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Old 02-13-2020, 08:34 PM   #7 (permalink)
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Quote:
Originally Posted by DieselPro View Post
Radiator is acting as a battery. Antifreeze needs changing.
Oh yeah...... I forgot about that. Acid builds up in the coolant and you have a battery. DP is right on. Time to change /flush the coolant.
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If Americans ever allow banks to control their currency. First by deflation then inflation. The banks will deprive the people of all property. Until their children wake up homeless.
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New Bosch injectors. Flow matched 2200 lbs pop
3 1/2" custom Aero turbine exhaust. Nutered Cat
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Last edited by Tommygunner; 02-13-2020 at 08:35 PM.
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Old 02-14-2020, 02:36 AM   #8 (permalink)
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You could also be reading the corrosion between body and frame or something like that. A digital meter doesn't put much load on things so they will practically read the voltage just from the air. A potato likely has a more amps (and volts) in it than you are getting from your truck.
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Old 02-14-2020, 08:57 AM   #9 (permalink)
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Wow, I'm glad I posted this question. I'm tending to go with the capacitor theory since the voltage continued to drop. I read it yesterday afternoon at 0.1 v and I'm testing with the batteries completely disconnected from the truck. I'll check the pH of the coolant and will see if I can read any charge from the coolant itself. I'm having a hard time wrapping my head around how a radiator acting as a battery could put current into the electrical system of the truck, like at the cigarette lighter. With quite a few years on the coolant but only a few thousand miles, it's probably due to be changed anyway. pH should tell me something about that. I'll check my meter on a potato. I think there's one still in pretty good shape out on the compost pile and maybe one still in the house. We do have some good sweet potatoes. Thanks y'all!
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'94 K3500 Silverado DRW long bed crew cab 4X4 with most of the options
Bought on 3/23/11. Current mileage 161,805
It came with new 6.5L TD Goodwrench crate motor dealer installed at 99k miles and 4L80-E trans rebuild at 135k miles
G80 4.10 rear, 225/75 16 tires
New Stanadyne FSD on 3x6x1 aluminum heat sink, remote mounted above and behind the bumper.
Heath Turbo Master, Hayden SD fan clutch & trans cooler
Diamond Eye 4" exhaust, GlowShift diesel combo gauge. Analog EGT, Digital Boost & Trans Temp
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Old 02-14-2020, 10:03 PM   #10 (permalink)
SRR
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There wasn't any need to check the pH of my coolant. It's carrying 0.25 volts. I will check the pH but only to satisfy my curiosity and will do it on a much nicer weather day.


The electric system itself went down to 0.06 volts.

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'94 K3500 Silverado DRW long bed crew cab 4X4 with most of the options
Bought on 3/23/11. Current mileage 161,805
It came with new 6.5L TD Goodwrench crate motor dealer installed at 99k miles and 4L80-E trans rebuild at 135k miles
G80 4.10 rear, 225/75 16 tires
New Stanadyne FSD on 3x6x1 aluminum heat sink, remote mounted above and behind the bumper.
Heath Turbo Master, Hayden SD fan clutch & trans cooler
Diamond Eye 4" exhaust, GlowShift diesel combo gauge. Analog EGT, Digital Boost & Trans Temp
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