Unknown battery drain

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04yuke

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Consider this: Truck sits for a few weeks and you drive it for an hour. Two weeks later you drive it for 30 minutes. Two weeks later you drive it for 2 hours. A week later you drive it for 30 minutes. What do you think the state of charge will be after all this time? I'll tell you what, it's going to be pretty low. Put a battery tender on it.
I just put a ctek tender on it. We'll see how it goes.

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George B

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Consider this: Truck sits for a few weeks and you drive it for an hour. Two weeks later you drive it for 30 minutes. Two weeks later you drive it for 2 hours. A week later you drive it for 30 minutes. What do you think the state of charge will be after all this time? I'll tell you what, it's going to be pretty low. Put a battery tender on it.

This is true. I would use a tender to keep it up to *****. The short cycles are ******* the battery anyway.
 

OR VietVet

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When you do the test light test you can also do the alternator power up wire to see if the light dims considerably. Like has been said, there are draws, minimal, for "keep alive memory", like the clock at the dash and the mentioned modules. If you have an internal diode problem with the alternator that can drain a battery. Good luck.
 
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04yuke

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When you do the test light test you can also do the alternator power up wire to see if the light dims considerably. Like has been said, there are draws, minimal, for "keep alive memory", like the clock at the dash and the mentioned modules. If you have an internal diode problem with the alternator that can drain a battery. Good luck.
Good point. Thanks for the reminder.


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04yuke

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Good point. Thanks for the reminder.


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If it was an alternator diode, would it still charge? Bc it does. Otherwise it's either death throws of the battery or a parasitic draw.

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OR VietVet

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A diode is designed to allow current to flow one way. If it goes bad that means current flow is reversing thru it and that can drain a battery. It can still charge but eventually that will stop as well.
 

Yukon_

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I have an 04 Yukon that has developed an unknown battery drain. The battery checks out good. I've changed nothing. This mystery drain started 2 weeks ago. I had an fm transmitter with USB charge ports plugged into the aux power outlet. It's been there for months but thought that maybe it was the drain source and unplugged it. No help.
It's a gradual drain. Takes about a week to drain enough to need a jump.
This is a project vehicle and not my DD. Any suggestions for isolating the power leach would be appreciated. TIA

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Have the Red & Black battery cables checked (even inside of the jacket) could be corroded. Would need to replace. A few years back my 07 Tahoe had this same issue, and after replacing the negative cable the issue was over.
 

McIntosh777

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I have an 04 Yukon that has developed an unknown battery drain. The battery checks out good. I've changed nothing. This mystery drain started 2 weeks ago. I had an fm transmitter with USB charge ports plugged into the aux power outlet. It's been there for months but thought that maybe it was the drain source and unplugged it. No help.
It's a gradual drain. Takes about a week to drain enough to need a jump.
This is a project vehicle and not my DD. Any suggestions for isolating the power leach would be appreciated. TIA

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Im thinking one Bad Diode in Rectifier for the alternator can cause this.Its not a common problem but it does happen.
 

OR VietVet

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Yea, lots of times the corrosion builds under the insulation and if bad enough you can see the swell of the insulation itself but sometimes not, but it is there. When you replace the cable you can cut open the insulation of the old cable and it will be loaded with white corrosion covering the wire. That creates a major source of resistance to electrical flow.
 

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