Parasitic Drain?

[AZJeepGuy]

Good morning,
Just went out and my Jeep is dead. Click but not enough juice to turn it over. I have had two small batteries replaced. The 2nd about a month ago. I noticed a bit of a slow start the other day but didn't think about it. Has anyone had an issue with parasitic drain?

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[6.2Blazer]

How old is the larger starting battery? How cold is it out? How long as the Jeep been sitting?

 

[SparkleTooth]

It’s the batteries. The JL charging system in its own right is one giant parasitic drain. Replace the aux and main batteries……….every month

 

[OldGuyNewJeep]

Good morning,
Just went out and my Jeep is dead. Click but not enough juice to turn it over. I have had two small batteries replaced. The 2nd about a month ago. I noticed a bit of a slow start the other day but didn't think about it. Has anyone had an issue with parasitic drain?

3.6L? No eTorque? (i.e. main battery + small ATV battery rather than main battery + 48v eTorque battery)

Yes, the JL has parasitic drain. You need to charge at least bi-weekly if you’re not driving hundreds of miles per week. Most of us with the 3.6 yank fuse F42, disconnect the negative for the little ATV battery, and employ a SmartStopStart so that the “turn off ESS” button remembers its last state (off).

Do not make the mistake that I and other 2018 OGs made - a dinky trickle charger/maintainer does more harm than good. Get at least a 10a charger/maintainer like the Noco-10. Personally, I went with Odyssey’s 20a one.

Please see the video linked here: https://www.jlwranglerforums.com/fo...t-question-for-the-experts.66343/post-1785349

More threads:

https://www.jlwranglerforums.com/fo...l-battery-recommendations.115242/post-2395932

https://www.jlwranglerforums.com/fo...l-battery-recommendations.115242/post-2396074

 

[AZJeepGuy]

Thanks for the quick reply. 2L, 31k miles. Drive 250 miles per week. They changed the two small batteries but not the big one. And no go on a trickle charger, no power where I park. Going to go buy a jump box and bring it to the dealer.

 

[Ratbert]

Thanks for the quick reply. 2L, 31k miles. Drive 250 miles per week. They changed the two small batteries but not the big one. And no go on a trickle charger, no power where I park. Going to go buy a jump box and bring it to the dealer.

The way the two batteries are wired results in a scenario where if one goes bad it takes the other with it. Replacing just one has been shown to be futile.

 

[GATORB8]

Thanks for the quick reply. 2L, 31k miles. Drive 250 miles per week. They changed the two small batteries but not the big one. And no go on a trickle charger, no power where I park. Going to go buy a jump box and bring it to the dealer.

Two small batteries?

 

[Whaler27]

Is the jeep being driven regularly? They all have some parasitic drain. You can measure the amount of the drain with a multimeter, but make sure the Jeep is turned off for at least a minute before you measure, because it takes some time for the brain to shut down.

Never replace just one of the batteries.

 

[MicFitz]

Same thing for me. 2021 with 47000 miles. Auto start light came on less than 2 weeks ago, and big battery is a no crank Saturday morning. Definitely replace them both.

 

[AZJeepGuy]

Quick follow up. I drive it everyday to work, so about 300 miles / week. Dealer had replaced the small battery about a month ago. This time it was the main battery. Replaced under warranty. Jinxed myself this morning when I called it a steaming pile of dog crap in the poll that's active.

 

[CMTAZ]

It’s the batteries. The JL charging system in its own right is one giant parasitic drain. Replace the aux and main batteries……….every month

That's a terrible exaggeration, they're good for




at least 60 days (but not 90)


Side note: ALWAYS REPLACE BOTH BATTERIES, by the time you discover one of them is bad, the other one is on the way out.....

 

[Hard Rock Jeep]

There are plenty of YouTube videos showing how to do a parasitic draw test. But if you do not take the time to do it right, you may get false readings. The goal is to know what is pulling power from your battery when it reaches its steady state.

When you first attach your multimeter to the negative post and to the ground wire, understand that by reconnecting your wires (thru the multimeter) you are waking up your system. That means that many things are now alert or on. Most of these will go back to sleep when nothing else occurs. What does not sleep is what you want to read as the parasitic draw.

This means that your connections to the battery/wiring must be secure for several minutes, or you will re-wake up the system and get erroneous readings.

I have attached some pictures of my multimeter doing a test on my 22 JKUR Diesel. The first picture was taken at 3:17pm and shows the wake up pulling 2.011A:

The next picture taken a minute later at 3:18 is pulling .526A (five hundred twenty six milliamps). This would be huge problem, but wait:

Two minutes from the start it is reading 54 milliamps:

Then it reaches steady state four minutes later at 3:21 at 13 milliamps which is entirely acceptable. Generally you want under 50 milliamps, lower the better.

 

[SunnyFLJeep]

Good morning,
Just went out and my Jeep is dead. Click but not enough juice to turn it over. I have had two small batteries replaced. The 2nd about a month ago. I noticed a bit of a slow start the other day but didn't think about it. Has anyone had an issue with parasitic drain?

My wife’s jeep had this issue. All of a sudden her battery died. Jumped it, died 2 days later again. AutoZone Replaced the battery. Put the new battery in and the next day it died. Jeep was Drawing 4 amps when off. After 2 mechanics i know looked at it with no luck, i took it to the dealership. After a week there they finally isolated the problem: keyless entry on the passenger door. Disconnected it (no power lock and power window on passenger side now) and battery didn’t die. Part is on order now. Frustrating as hell but relatively simple solution.

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