Parasitic battery drain

[EternalHobbyist]

Hey guys, I've battled a parasitic battery drain on my jeep for years. I've just put up with it because it wasn't that bad, and I had the tools to jump it at home as well as when I was out and about. Well, a week or so ago, I went to a car show/cruise, and it wouldn't start after I had it parked and had charged the battery. I purchase a new battery and decided to get to the bottom of this battery issue. I checked the alternator, and it is running just fine. So I tested the drain on the battery and found it to be only 52 milliamps. According to my google searches, that is pretty much exactly normal.

I got one of my trickle charges out, confirmed it puts out more than that, and hooked it up. I THINK I just had a bad battery. Problem solved.

However, because I like to double check my work, I thought I'd ask you guys if you have tested this on your TJ's???? And what are you getting for a parasitic drain??

...they will always pull some power with the radio memory etc...

 

[CreepinDeth]

Pull the fuse for the stereo and check parasitic drain with the radio out of the equation.

I can tell you its easy to pull the key out, and THINK you have it all off, but a loose tumbler can often go partially to accessory mode and keep the radio on

Also, just my .02 here
Eliminate all incandescent bulbs and go LED

 

[FarFire70]

How old is the battery?

Sounds like you have the tools and ability to test the draw. How/where did you test that current draw?

That draw does sound normal but did you confirm what's pulling that draw?

How old is the battery and how has it been treated?

 

[FarFire70]

Don't forget the underhood light when tracing down a current draw. I wasted too much time once trying to find the last few mA draw only to realize the freaking underhood light was the last bit I hadn't eliminated to get to a zero draw...

 

[EternalHobbyist]

I pulled the negative off the battery and put my meter on the negative battery terminal and the negative cable. That gave 52 milliamps draw.

I also pulled the radio fuse and that only dropped it down to 47 milliamps draw. That did surprise me. I expected more.

I didn't chase it past that because everywhere I read shows 50 milliamps is normal.

Also, thanks for the tip on the hood lamp. I had already confirmed that. I have that stuff disconnected semi-permanently.

 

[EternalHobbyist]

Oh, and I put a new battery in it. So it is brand new now.

 

[FarFire70]

Sounds like you're doing it right. (Can't say if running off the neg vs pos is better from a safety perspective, but it gains you the right data)

Keep pulling fuses until you know what the draw is. At least then you know. PDC & Fuse block behind the glove box.

Reporting that here will help with the diagnosis if you can get it to zero.

Amperage seems low draw unlikely to kill a new battery.

I checked the alternator, and it is running just fine.

Was that at an auto store? Consider trying another auto shop/store to confirm performance.

 

[FarFire70]

How do the cables look at the battery/alt/starter?

Perhaps corrosion at a terminal is giving intermittent performance.

 

[EternalHobbyist]

Sounds like you're doing it right. (Can't say if running off the neg vs pos is better from a safety perspective, but it gains you the right data)

Keep pulling fuses until you know what the draw is. At least then you know. PDC & Fuse block behind the glove box.

Reporting that here will help with the diagnosis if you can get it to zero.

Amperage seems low draw unlikely to kill a new battery.



Was that at an auto store? Consider trying another auto shop/store to confirm performance.

I'll do some more fuse pulling/investigating when I get home from work today. It would be nice to see if it is possible to get it even lower.

I had the alternator checked at advanced auto, but you're right, it would be a good idea to double check their work.

How do the cables look at the battery/alt/starter?

Perhaps corrosion at a terminal is giving intermittent performance.

The cables at the terminal are pretty clean. I know that the positive side is good because I did some work to it last year, and it appears to be in great shape. The only thing that I can't remember if I checked is the negative cable that I assume grounds to the frame, firewall or engine block. I'm sure I've checked it before, but it is probably work taking apart and cleaning.

I steam cleaned the engine last year.... but I don't remember what that negative lead looks like.