ESS charging

[JLFoxOR]

Hello, I recently purchased a 2018 Wrangler JL. The ESS system light was on so I went ahead and replaced the Aux battery. The system was working fine for several days then I didn't drive it for a few days and started getting a "not ready battery charging message". This failed to resolve after a few days so I pulled the F42 fuse and disconnected the Aux battery negative lead as suggested. The ESS system is working now.

Question: I noticed that the battery voltage with both batteries connected was 14.4v and with just the main battery is 14.1v. Is that what causes the problem that the batteries are dissimilar and trying to charge to different voltages?

Next question: is there any downside to leaving the Aux disconnected permanently?

Thank you for your help.

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[rohdawg]

Question: I noticed that the battery voltage with both batteries connected was 14.4v and with just the main battery is 14.1v. Is that what causes the problem that the batteries are dissimilar and trying to charge to different voltages?

No. The JLs have an intelligent charging system. You’ll see the voltage fluctuate during driving/coasting and idling. It’s normal.

The biggest problem is the stock batteries are garbage. Yours being a 2018, if they were stock, they were past due to be swapped.
You should consider changing out your main as it is probably close to being a problem as well.

Next question: is there any downside to leaving the Aux disconnected permanently?

If done correctly, no.

 

[DaltonGang]

@JLFoxOR ,
If you don't change the main with the Aux, you run the risk of the main possibly going bad and trashing the aux battery. When you have two, and one goes, the good one is usually severely weakened.
https://www.jlwranglerforums.com/fo...sing-the-aux-battery-easiest-solution.100296/

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