Battery Issues

[Marineldo05]

2019 Rubicon with 3.6 bought 4 months ago. Had gotten a few dash messages stating aux switches not available, battery charging. But had no issues starting. Other morning it wouldn't start. Hooked up battery charger for a couple hours and it started. Decided to replace both batteries. Now battery voltage is fluctuating between 10.6 and 11.6 and have dash warning that says, "Stop Safely, Vehicle Will Shut down Shortly." Both batteries tested ok. Any suggestions?

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[cbmjeep]

Check to make sure all fuses are seated in the fuse box and relays.

 

[Punkn89]

I had that aux warning for 2 weeks and after I replaced my key fob battery, it stopped showing up. WEIRD!

 

[entropy]

2019 Rubicon with 3.6 bought 4 months ago. Had gotten a few dash messages stating aux switches not available, battery charging. But had no issues starting. Other morning it wouldn't start. Hooked up battery charger for a couple hours and it started. Decided to replace both batteries. Now battery voltage is fluctuating between 10.6 and 11.6 and have dash warning that says, "Stop Safely, Vehicle Will Shut down Shortly." Both batteries tested ok. Any suggestions?

The voltage for your new batteries is very low. I suggest you charge it with a Noco trickle charger for 48hrs or similar. And then run the "repair" mode once or twice. Also make sure you don't have anything draining your batteries, such as a hidden dealer installed GPS locator. I had one in my Jeep and removed it about 2 years ago.

I had very similar issues and eventually my main battery died so I replaced both with nice expensive batteries. 720 CCA Odyssey for the main and diehard platinum for the aux. I drove for a few months and everything was fine until I started getting messages about battery charging and all that.

I was frustrated so I decided to isolate the main battery from the aux. When I tried to start the Jeep to my surprise it didn't start. Main battery resting voltage was 10.8 and the aux was at 12.8. I learned something very important. Your aux battery can kill your main battery. The aux battery can start the Jeep and hide real issues. When voltage drops very low the main fails to recover on its own. Your Jeep will run for days, weeks, until the little battery craps out. Then both batteries have been damaged and you never knew

So I recharged my main battery with my Noco charger for 48hrs. Followed by repair mode to fix any surface sulfation issues. I did this several times over a week's time.

I got enough of the dual battery system. It is more expensive on the long run than whatever you save in gas. It is a poorly designed and unreliable system. The aux battery has a huge resistance and it will weaken the main battery because they are connected in parallel.

Best thing you can do is what I did. bypass the aux battery by disconnecting the negative aux cable and removing fuse F42. Disable ESS. This will also help you troubleshoot any battery issues much easier.

https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

I did this and tested both batteries with a battery tester and also performed load tests for over a week. Both batteries are very strong now and always charged. I can keep my aux charged by either plugging it back to the Jeep for a long drive every other week so the alternator charges it or by using my noco charger every other week. The aux battery can now be used to start the Jeep in the case my main runs out of juice or I accidentally kill it. This imo is the best use for the aux battery. All I have to do is plug that cable back and it works.

Believe me I performed so many tests on these batteries and learned so much about it this past year, the BEST thing you can do is bypass the aux. I do tax my battery quite a bit with my 50amp compressor and my winch. I use both regularly. So I realized I cannot run a weak battery system. Everything used to work fine until I went offroad, then I would have issues. Now with the aux bypassed everything runs perfectly fine and I have no issues and peace of mind that if my main dies in the middle of nowhere I can start with the little battery.

 

[58Willys]

Check battery grounds, and check charging system (alternator output).

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