Is this how the dual batteries function in Wrangler JL?

[Capricorn]

Main battery - provides for HVAC, light, radio, ECU and other critical system functions.
ESS/Auxiliary battery - ESS and Ignition Start

During stop/start active mode, the computer is monitoring the main battery. If the main battery charge falls to some threshold of charge, the ESS starts the car to let the main battery gets charging.

Is this correct?

And how does the ESS/Auxiliary battery gets charged? By the alternator or by the main battery?

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[WranglerMan]

I wish I knew but as long as it starts when I push that button I’m good, I do wish they had made the battery easier to get at, the one that’s under the main battery.

 

[W1ck3d]

The axillary battery controls all the interior features radio, lights, dash, basically everything on the interior

I wish I knew but as long as it starts when I push that button I’m good, I do wish they had made the battery easier to get at, the one that’s under the main battery.

Its not to bad to get too.... 3 bolts get to it through the rt side flare... But it also depends on why you'd want to gain access to it.. If it was for charging purposes you can disconnect the 1 & 3 terminals from the pdc (fuse box) and hook the charger up to those terminals

 

[abacus_programmer]

These videos may help you out. The wiring diagram video was a little slow but as he zooms in and out you can probably understand more of what's going on.

Wiring Diagram --
Battery Physical Access --

 

[Capricorn]

The axillary battery controls all the interior features radio, lights, dash, basically everything on the interior


Its not to bad to get too.... 3 bolts get to it through the rt side flare... But it also depends on why you'd want to gain access to it.. If it was for charging purposes you can disconnect the 1 & 3 terminals from the pdc (fuse box) and hook the charger up to those terminals

Including A/C? And also the starting?
Then there's hardly any function left for the main battery except for ECU and exterior lights.

 

[W1ck3d]

Including A/C? And also the starting?
Then there's hardly any function left for the main battery except for ECU and exterior lights.

The a/c im not to sure about i don't work with a/c much, but id assume a/c runs off both due to when the engine shutting off at the light but the a/c still works without the compressor running... But dont forget about the things you dont normally see.... The big battey operates the bcm, pcm, orc mods, and a bunch of other modules ect ect alot of the stuff you may not see

 

[Nutcracker]

OK with Dual Batteries where do you connect a winch? Are either battery sufficient to handle a winch or should one battery be changed for a deep cycle battery?

 

[Rhinebeck01]

@Nutcracker

Do give your post here a day or two to solicit responses from other JL owner's that have actually installed a winch on their JL, had it up and in use for a while. There are lets say caveats you will need to be aware of if you want a successful, non-problematic install.

The JL's battery(2) /// electrical is new, quirky and reality is everyone here is guessing.... trying to get a grasp on all the in's and out's lets say.

One thing to research on ... to learn about is, when you do hook up to the main battery (if you do use it), which side of the positive terminal's connector to attach your winch positive cable to. you do not want to attach on the same side that a sensor is attached to.

I will let you research this for yourself. Just be careful of what you read in forum threads as there is a resident nut job that is lets say confusing things in regard to the JL's electrical/batteries.

DO zero in on posts / replies from those that have actually installed a winch.... have had it installed for awhile, and have actually used it.

Watch to see if they have ever posted info on the forum where they mention battery getting depleted or ESS battery issues, JL won't start, etc.. Anyway, do your homework before you make the leap lets say.
YES, there are those here that have non-problematic winch installs.

Also, do read up in regard to the Tazer JL programmer and it's "Winch Mode". Winch Mode is a feature you might like to take advantage of when using that winch once you get it installed.

'

 

[Capricorn]

OK with Dual Batteries where do you connect a winch? Are either battery sufficient to handle a winch or should one battery be changed for a deep cycle battery?

My guess is the main top battery which is visible. The smaller ESS battery is a layer or two deep below the main battery and cannot be reached easily.

 

[Jeepsk8]

OK with Dual Batteries where do you connect a winch? Are either battery sufficient to handle a winch or should one battery be changed for a deep cycle battery?

You should hook it to the main battery. The amp draw from a winch is significant and the main battery acts like a buffer to handle the load sufficiently. There is an empty post on each battery connector to hook to. I installed a relay to disconnect power to the winch (I had one runaway once, not fun, so this solves that dilemma) but that is not mandatory.

 

[Jebiruph]

The JL's battery(2) /// electrical is new, quirky and reality is everyone here is guessing.... trying to get a grasp on all the in's and out's lets say.

One thing to research on ... to learn about is, when you do hook up to the main battery (if you do use it), which side of the positive terminal's connector to attach your winch positive cable to. you do not want to attach on the same side that a sensor is attached to.

The sensor is on the negative terminal, that just show's how confusing it all is. I created a diagram to help people sort out the battery connections.
https://www.jlwranglerforums.com/forum/threads/3-6l-ess-battery-diagram.14401/

 

[Rhinebeck01]

@Jebiruph Well, at least I knew there was a sensor that you have to take into consideration and avoid when connecting to that battery. 8-)

I had read it was on the negative.. not sure why I said positive..

As I told the guy in that post, do your homework.

I knew I did not have all the answers and that I myself, might very well even, fumble the ball so to speak.

I encouraged him to be very wary of what he read / heard on the forum... and that things were confusing overall...

YES, very confusing and usually I pick up on things real easy. I do feel I have a clue but not a lot of clues in regard to the JL, it's batteries///electrical.

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