Will this battery fit?

[GrayWolf.Overland]

Later model 2018's and model years beyond, and those early 2018's with TSB 18-092-19 will, upon detecting a dead or unconnected Aux battery not crank, but on second user attempt switch all power to the main battery and turn ESS off, displaying that ESS is off in the dash EVIC.

Thanks for the explanation @Fudster . Does the following statements right now considering your explanation above.

After one disconnects the AUX and sees the above-mentioned EVIC for ESS off.. they may choose to live with it OR they can go ahead and remove the Fuse 42 - in which case it will suppress the ESS Off EVIC message.

Using ESS in such a setup (Aux disconnected, Fuse 42 removed) is perilous as it means there is one battery for everything - i.e. you can drain the main battery even in one ESS Stop event in case you have enough aftermarket electronics connected.

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[Fudster]

Thanks for the explanation @Fudster . Does the following statements right now considering your explanation above.

After one disconnects the AUX and sees the above-mentioned EVIC for ESS off.. they may choose to live with it OR they can go ahead and remove the Fuse 42 - in which case it will suppress the ESS Off EVIC message.

Using ESS in such a setup (Aux disconnected, Fuse 42 removed) is perilous as it means there is one battery for everything - i.e. you can drain the main battery even in one ESS Stop event in case you have enough aftermarket electronics connected.

Hi Sabash:

I use "ESS battery" and "Aux battery" interchangeable below to mean the little battery.

It is beyond the depth of my knowledge, although @Rhinebeck01 or Jerry @Jebiruph may know, if pulling Fuse 42 after the ESS off light in the EVIC has appeared due to a disconnected Aux battery, followed by what is usually 2 engine crank attempts, (the first failing) will then cause that EVIC light to turn off.

My understanding, which may be incorrect, is that Jerry may have yanked fuse 42 first before disconnecting the Aux battery.

Yes, using ESS with on battery is perilous, but, and this is important Sabash, impossible based on two factors, either one of which on its own prevents ESS from engaging. The first is that disconnecting Fuse 42, from Jerry's testing appears to prevent ESS from ever engaging, and does so with no sign to the vehicle operator, even if the ESS battery is still connected I believe.

The second is that the cold crank immediately after you've disconnected your Aux battery is likely to fail if Fuse 42 is not pulled. (I don't know what happens if the fuse is pulled first.) Your second attempt at cold cranking then illuminates the ESS off light, preventing ESS events from ever happening again, for all cranks thereafter, and switches all power to the main battery, and attempts to crank from there.

Even with Fuse 42 not being pulled, ESS will never turn on again unless a) the factory leads to the ESS battery that you've disconnected are reconnected to a power source, and the vehicle is recranked, and b) fuse 42, if pulled, is reinserted.

There is certainly nothing wrong with not pulling Fuse 42 and living with the EVIC light. It's not the way I'd prefer it for cosmetic reasons and like Jerry's approach with the fuse, but know that you do no harm by not pulling that fuse.

I hope that helps.

 

[GrayWolf.Overland]

Clear as light! I am going to pull the fuse, disconnect my AUX battery negative, and install an AGM 94R H7 size battery and call it good.

@Fudster - I really appreciate your patience in explaining every detail and possible options with the system.

 

[Chocolate Thunder]

So I see that some remove the AUX battery from the system by pulling fuse 42 and disconnecting the negative cable to it. Why not simply physically remove the AUX battery entirely?

 

[Rhinebeck01]

So I see that some remove the AUX battery from the system by pulling fuse 42 and disconnecting the negative cable to it. Why not simply physically remove the AUX battery entirely?

@Chocolate Thunder

My reason not to remove/delete the Aux battery completely and rerun the cables was/is for vehicle resale reasons and not because I couldn't easily do the Aux delete myself...

Yes, I have replaced a bunch of Aux batteries and also have removed/deleted the Aux battery on a few guys and gals JL's. (they pay me to do) Not hard to do really....... well, the actual Aux delete is a tad more work..

... BUT it's far far easier, to just leave the unwanted or dead or failing Aux battery in place and pull fuse F42 and disconnect the Aux neg. wire on the Main battery.... and to just leave the Aux battery there doing nothing.... nothing but sitting in a plastic box and adding very few # of weight... (Yes, and for the driver also remembering to minimize the use of the JL's, ESS feature.)

Anyway, not all Jeep owner's are like you and I and some other's here. Some owner's here do not wrench of their vehicles.. Reality is many here do not even change their own motor or diff oil.

To do the Aux delete is not something they/many want to do... to pay someone else to do the delete, is something they do not want to do... they may be leasing the vehicle so they do not want to do for obvious reasons... they are still covered under warranty..some are anti, cutting stock wiring/harnesses, etc...

Takes all but about 3 minutes to pull F42, disco a single cable and be dealing with just the Main and not have the headaches that the an Aux battery in the mix brings for most.

By the way, I have driven for over 2 years now and over 50,000 miles with just the Main battery and the Aux battery just sitting there in the Aux battery box doing nothing. IF I did not know better, in daily use of my JL, I'd think I was running the factory dual battery system as designed. But .... my JL is just like my past JK's and other Jeeps.... it's running with just the Main and never any Aux related issues.

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[Chocolate Thunder]

So there’s no reason not to remove it. Thanks!

 

[Jebiruph]

So I see that some remove the AUX battery from the system by pulling fuse 42 and disconnecting the negative cable to it. Why not simply physically remove the AUX battery entirely?

If the aux battery is still good and can hold a charge, it can be used as an emergency backup battery if left in the vehicle.

 

[Chocolate Thunder]

If the aux battery is still good and can hold a charge, it can be used as an emergency backup battery if left in the vehicle.

Will it not die in short order while it’s disconnected just sitting there in the heat if the engine bay with no charging?

 

[Go_Galt]

This is great thread. I appreciate you guys laying this all out. Very informative.

 

[Rhinebeck01]

Will it not die in short order while it’s disconnected just sitting there in the heat if the engine bay with no charging?

@Chocolate Thunder

My 2018 JL left the factory in May of 2018. The original/factory Aux battery that sits unused in the small battery box still tests aok..... and undoubtedly is useful to this day as a b/u battery should I need it for that.

YES, every 2-3 weeks, I do hook up a battery tender maintainer to the Aux battery... When the Aux battery finally fails, I will let it rest in piece...

Eventually though, should the new/future owner of my very well maintained (not bastardized) JL, (when I sell it) want to install a new Aux battery and run with the factory dual battery system it will only mean the new owner needs to easily drop in a new Aux battery.

 

[AnnDee4444]

What's the consensus on Optima batteries? I'm considering their Yellowtop DH7, hoping that it will deal with winching/compressor loads better than the factory battery (which is approaching 4 years old...)

Also my start/stop is constantly in a state of charging/not ready (2018 eTorque 2.0). Would this have any impact on battery selection? I'm assuming that the eTorque battery has some influence over the charge rate of the 12V battery.

 

[rhocking]

YES, every 2-3 weeks, I do hook up a battery tender maintainer to the Aux battery... When the Aux battery finally fails, I will let it rest in piece...

How do you hookup the battery tender to charge the Aux battery with the Aux Negative disconnected (and presumably wrapped to avoid shorts)?

With Aux in places I believe it is preferred to connect to the Red terminal on main and to one of the Negatives such that the IBS is in the circuit. I am guessing that to charge the Aux battery, you connect to the Red terminal and unwrap the Aux Negative or do you have some fancy solution to make the charging of the Aux battery easier?

 

[Rhinebeck01]

How do you hookup the battery tender to charge the Aux battery with the Aux Negative disconnected (and presumably wrapped to avoid shorts)?

With Aux in places I believe it is preferred to connect to the Red terminal on main and to one of the Negatives such that the IBS is in the circuit. I am guessing that to charge the Aux battery, you connect to the Red terminal and unwrap the Aux Negative or do you have some fancy solution to make the charging of the Aux battery easier?

@rhocking

I suggest guys/gal's just use a short length of wire loom tubing to cover the Neg Aux cable end when they have the Aux Neg cable disconnected from the Main 's Neg terminal.

Wire Loom Tubing- Split Loom Cord Protectors, Flexible Wire Conduit Automotive, Black

Then when they want to charge / maintain, just the Aux battery..... they connect the battery tender's red clamp to the Pos terminal on the Main battery and they just slide the loom cover off the end of the Aux Neg cable and that allows them to easily connect the Aux Negative cable end, using the battery tender's black clamp.... and then do the charging/maintaining of just the Aux battery.

With the custom set-up on my JL, I charge the Aux alone as pictured here:

 

[rhocking]

@rhocking

I suggest guys/gal's just use a short length of wire loom tubing to cover the Neg Aux cable end when they have the Aux Neg cable disconnected from the Main 's Neg terminal.

The wire looming is an excellent idea. Had not thought to use that.

Your Metering setup looks very slick. Might have to look into this.

 

[Rosco1983]

Can you fit a H8 battery?

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