Weird battery problem...

[crw]

Year 2000. 4x4, 1500, but pretty spartan. No power seats, pretty basic inside.

I think there may be some direct short to ground. My pulling the RAP fuse prevents it when the truck is off, but when it runs it seems a little sluggish. Maybe...

 

[oppirs]

What does RAP stand for don't wanna look it up.

 

[crw]

Retained Accessory Power

 

[3311]

Originally Posted By: crw
Year 2000. 4x4, 1500, but pretty spartan. No power seats, pretty basic inside.

I think there may be some direct short to ground. My pulling the RAP fuse prevents it when the truck is off, but when it runs it seems a little sluggish. Maybe...
I would doubt you have a direct short to ground. It's not pulling that much current. Have you disconnect the battery then checked for a ground/short with a meter?

Something must be running/stuck on.

Edit: After re reading the thread did you ever take the battery back and have load tested at WM? Is the is the same battery that was discharged to 0 volts?

 

[jim302]

When you connect the meter during the parasitic draw test, several modules such as the BCM wake up since battery power was lost and restored during the process. Make sure that you wait a few minutes before taking the reading, and that no lights (including an under hood light if there is one) are on.

It sounds like you have substituted a known good battery, but if not, make sure to get the new one tested just in case it is bad.

 

[crw]

Update: I seem to have isolated the problem with fuses. If I pull both the RAP #1 fuse (retained accessory power) and the radio fuse, now the battery will go through the night without discharging.

So, now I can drive around without the functions that the radio fuse controls (mentioned earlier). I think I might just take it to a local place and have then swap the radio out. I could do it myself, but on modern vehicles I just hate tearing into things...

Anyway, the assumption is the radio at this point. I checked interior lights, etc. No lights stay on.

 

[crw]

Quote:

I think there may be some direct short to ground. My pulling the
Edit: After re reading the thread did you ever take the battery back and have load tested at WM? Is the is the same battery that was discharged to 0 volts?


So, just to reiterate, I have two GM style batteries. One new, one from my old truck. Either one of them will be discharged overnight (or even in as little as an hour) if I leave it connected with the two fuses in. So it's not the battery.

If I pull the two fuses, the current draw problem seems solved. Now it's a matter of finding out where the current draw resides. I think I can live without the RAP, which controls devices that stay on after the key is turned off (radio stays on until the door opens, etc.) but this seems to be related to the radio so that's my next suspect.

 

[ltslimjim]

Okay, so it does sound like the radio has an issue drawing too much when the engine is off. Bad radio!

 

[jim302]

Pull the radio and then put the fuses back in just to make sure. If this fixes the drain, it might be worth looking into an aftermarket unit.

 

[crw]

Eh, I just had my wife take it in and we're getting a new radio put in. The technician said that he had seen this problem several times before, although he might have been just trying to sell a radio. We shall see!

 

[crw]

OK, I just want to post to tie up this thread. It was the radio!

I had a new one put in, and now it's all good, fuses are back in, and the battery isn't taking a dump every night.

I hate it when threads end and no resolution is posted. Someone will search out this thread years from now and hopefully will find some ideas.

 

[crw]

Oh, and another thing... The help on this board is invaluable. This would have cost me a ton more without your help. Thanks!

 

[oppirs]

Originally Posted By: crw
Oh, and another thing... The help on this board is invaluable. This would have cost me a ton more without your help. Thanks!


Cool, glad your happy & had a tech confirm it. Always scratch my head why a radio in these GM wanted to drain? I thought it was becuze I stop subscribing to OnStar. Not true for one subscriber. Did the same thing to her as an active OnStar user.

 

[crw]

Well, one more... for posterity's sake.

The battery did take one more dump, after a longer downtime to drain. And I was sorta expecting it... So I pulled and permanently removed the RAP #1 fuse (retained accessory power), and now it appears to be good. Now when I do the current draw test, when I first connect it it pulls about 0.6A for about one minute (starting the computers?) then it drops to about 0.06A steady DC current.

It was the radio, but the problem was also in the RAP to some degree.

 

[Vikas]

0.06A is just higher than nominal 50mA drain current. A good battery should be able to handle that for days. Assuming 100Ahr battery rating, you are talking weeks/months before it will be drained with that load.

I am sad to say that you have not really nailed it down yet.

- Vikas

 

[3311]

Did you ever have this battery load tested? If it was at zero volts as you said, there is an excellent chance it was damaged if it wasn't defective already.

 

[JHZR2]

Originally Posted By: 3311
Did you ever have this battery load tested? If it was at zero volts as you said, there is an excellent chance it was damaged if it wasn't defective already.


What's worse, 0V, fully sulfated, or 5.x V, for example, where a cell is shorted or in reversal?

Ever recover a 0V battery to be reasonably useful?

What is the lowest resting voltage that you would charge a PbA battery from and trust its utility? Or is it a case of measuring impedance after that to determine if it is useful anymore?