2019 jlu sport aux battery..replace or remove?

[Cerebellum]

Hey guys, advise on replacing Aux battery (a12 correct?) Or just remove. The jeep has been sending messages lately that all my systems are failing, assuming that's failing aux battery. Whats the result if I just remove it? Appreciate your input.

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[ScotM]

Tons of folks have removed it with no issues. I removed mine, including all the wiring and the really, disabled the start stop features and upgraded my main to an H7. Lots of good threads on how to do it. Simplest is remove aux negative cable and fuse 42.

 

[Dgr401]

I did not physically remove the auxiliary battery but I did remove fuse 42 and disconnected the negative terminal and taped it off.

 

[Ratbert]

I'm thinking most people that don't replace it simply bypass it (as noted by previous posts). That's option 3 of your 2.

 

[Speed331]

Yep, remove/bypass and dropping in an H7 main is your best long term option. I've had mine bypassed for 2 years without issue.
Hell, I even leave the start/stop on half the time.
I sometimes run a mail route in mine and that means turning the engine over 30 or 40 times with only a minute or so before turning off and have zero charge issues - whereas when I had the aux connected, I would get 'battery charging' warnings weekly when running a route.

The aux is less necassry then your appendix, and much easier to be rid of...

 

[AndySpill]

Hey guys, advise on replacing Aux battery (a12 correct?) Or just remove. The jeep has been sending messages lately that all my systems are failing, assuming that's failing aux battery. Whats the result if I just remove it? Appreciate your input.

All this assumes that you have a dual AGM battery JL.

First off, as written above, regardless of whether you replace, remove, or disconnect your Aux battery, because it is connected to the main battery in parallel, meaning that either battery's demise can effect the other, you would be wise, given the issues you report, to not simply replace the main battery, but do so with a group H7 battery, even if what you currently have is a slightly smaller group H6. (Depending on options, some JLs are outfitted with either of these two batteries as their main battery.)

Here's a list of main batteries: https://www.jlwranglerforums.com/forum/threads/main-battery-replacement-talk-jl-jt.100534/

As H7's often are the same price, or worth the slightly greater price for their capacity, it just makes sense to make this upgrade when replacing the main battery. If you have a group H6 now, you will need to remove a battery cleat in the bottom of the train to accommodate the larger battery.

With this said, attention now moves to whether to replace, disconnect, or remove the Aux battery.

That question is answered by whether you both want to and can run ESS (engine start stop events): two separate questions.

If you don't want or care to, the Aux battery not only isn't needed, but IMHO detrimental to have connected. It will serve no purpose and its demise (if connected, NOT if present but disconnected) can destroy a good main battery.

Disconnect the factory cable that is on the main battery's negative post that doesn't connect to the body ground (leave that cable intact) and electric tape up the now loose cable. Pull fuse F42 in the Power Distribution Center (PDC) and turn off ESS by pressing the button or buying after market tech to do that automatically for you.

You may want to run ESS events but don't drive enough to charge that Aux battery. In that case you'll need to trickle charge or follow the above guidance and do without ESS events. A trickle charger connected just to the main battery while the vehicle is at rest charges both batteries. A list of Aux batteries can be found here https://www.jlwranglerforums.com/fo...-way-pull-the-fender-flare.56807/post-1227002

Finally, to remove or disconnect the Aux battery. The Aux battery, a sealed AGM battery unlikely to leak, anymore than if it does, being closest to the ground in the engine bay is likely to cause no damage to other things if it does leak. If you want to do the extra work to yank it though, be my guest.

Finally, there is utterly no connection between turning ESS off at the dash, and physically disconnecting an Aux battery. A bad Aux battery will cannibalize the main battery no more or less regardless of the state (on or off) of the ESS button.

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