Batteries draining

[Turbinesurgun1]

2006 4x4 5.9 6 speed. Came out Sunday and batteries were completely dead. Not 1 volt. I assumed my buddy left key on. Charged her up, cranks and runs fine. Sat since Sunday night and it’s 100% dead again. Won’t even let doors unlock. Can anyone point me in the right direction? Nothing has been left on that I can find.

 

[sag2]

First have both batteries checked. Then if you have a DVOM you can check for an ignition off draw. The truck should go to sleep (around 50 mA draw) within a couple of minutes. Try and look for a couple Youtube videos on how to test, it would be easier than trying to explain it.

Here is an example of using amperage draw.


And this is using voltage drop.


There are a bunch of different ones out there. With two batteries, disconnect the positive cable on the passenger battery (insulate from ground with a rag) and do the test from the driver battery if your doing amperage.

 

[Turbinesurgun1]

Thanks much. Batteries are interstate and a year old but I do have a digital tester that I plan on testing if I can ever get the hood up. 99% certain it’s not batteries. Local mechanic/specialist things alternator just from texts. I bought the truck new in 05, she’s just now starting to give me troubles. Going to look at a newer car tomorrow for just riding but keeping all my trucks and hmmwv’s for the heavy work

 

[Ozymandias]

On mine the Alternator went bad and consumed the energy while parked.
Odd enough it wasnt permanently, only occasionally every other day or so.To diagnosis I pulled every and all fuses and still lost power. That pointed me to the Alternator, disconnected it and got it.

 

[User113]

You can also test the alternator first. Disconnect batteries. Disconnect Alternator. Fully charge batteries. Reconnect batteries. Use a high current ammeter, typically implemented with a shunt of some sort, to reconnect the alternator and see how much current is flowing through the alternator.

Something like: Amazon product ASIN B07QVXXGVR0-50A shunt.

Amazon item number B07QVXXGVR

 

[User113]

Hmmm... not sure I like how Amazon links are being handled!

But, my old alternator was leaking as well, and draining my batteries. Not as quickly as yours, but I would look there first.

 

[KParsons]

on my 06 i had a strange battery problem. the cross over cable was doing funny things it took a day to fix it. one side was dead and the other side was over charging. but they were both dead.

 

[Crunch]

on my 06 i had a strange battery problem. the cross over cable was doing funny things it took a day to fix it. one side was dead and the other side was over charging. but they were both dead.

The crossover cable is a notorious culprit for battery failure in these trucks, doing exactly what you describe in your post. But it's an easy fix, and not too expensive.

 

[EricViviano]

A quick and easy test I was shown years ago that works well for narrowing down the problem....

Unhook your negative battery cable, put a test light inline, it will illuminate if there is a parasitic draw. You can pull fuses and see if the light goes out, narrowing down which circuit it's in.

 

[sag2]

A quick and easy test I was shown years ago that works well for narrowing down the problem....

Unhook your negative battery cable, put a test light inline, it will illuminate if there is a parasitic draw. You can pull fuses and see if the light goes out, narrowing down which circuit it's in.

You have to be careful with that test. Depending on the quality of the test light and the bulb that it has (like an LED) you can get a false positive and chase your tail. Better to use a DVOM and see exactly what is happening. You can watch the amps drop as each module goes to sleep.

 

[EricViviano]

You have to be careful with that test. Depending on the quality of the test light and the bulb that it has (like an LED) you can get a false positive and chase your tail. Better to use a DVOM and see exactly what is happening. You can watch the amps drop as each module goes to sleep.

True. I use the cheap-o harbor freight light and I have mostly used it on older stuff. But have found a lot of issues over the years with it.