ESS Dual Battery Management

[Rhinebeck01]

So I did the remove the AUX Battery negative cable test and dash flashed and started right up. So thanks to you all for the peace of mind in this Post.

Food for thought for those JL 2018 production Jeeps:
So if I got my Jeep in Oct 2018, I think it took 2 weeks to ship, so Jeep sat in the lot awaiting for a truck to come down, leaves my Jeep may have been in production at QC in Sept 2018. So who knows if they fixed it then. I did run my vin for TSB 18-092-19 and did not show I needed it.

Who knows and thank again for you all sharing.

Jack

@MacJack

Good that you took the time / effort to check and see how your JL behaves.. This way, no rude awakening for you, thanks to a no start situation.

Reality is, the only way anyone that has a 2018 JL/JLU can absolutely know, is to do as you did and test...

Personally, I would not believe it, if the dealer told me TSB 18-092-19 had been done on my vehicle in the past.... They will often tell you, whatever, just to pacify you.. I'd still do as you did, and verify how exactly my vehicle behaves..

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[WranglerMan]

So I did the remove the AUX Battery negative cable test and dash flashed and started right up. So thanks to you all for the peace of mind in this Post.

Food for thought for those JL 2018 production Jeeps:
So if I got my Jeep in Oct 2018, I think it took 2 weeks to ship, so Jeep sat in the lot awaiting for a truck to come down, leaves my Jeep may have been in production at QC in Sept 2018. So who knows if they fixed it then. I did run my vin for TSB 18-092-19 and did not show I needed it.

Who knows and thank again for you all sharing.

Jack

I never tested mine but did carry a jumper and tested it for a few weeks but just always hated that motorcycle battery from day one so while visiting my favorite local Offroad shop in Houston @TTEChris of Tank Customs made a suggestion when I was in there discussing other work and now my worries of not starting are gone or at least I hope so.

There are a lot more cost effective ways of dealing with this battery but with the aux equipment I use I chose to go big or home and hey it’s a Jeep you are supposed to mod it right, anyways Jerry’s mods along with a few others have put together there own systems that provide peace of mind but I like the idea of running a full size battery to boost me if needed and I recently took advantage of it when I was in the woods so well worth the investment for me.

 

[MacJack]

Thanks for confirming my test... I did a vin check on Mopar.com as I agree with you dealers service could be as bad as the sales guys.... wait I had a good salesman because I ordered out of state and local dealer let me drop ship to him. Because he makes his money on aftermarket sales.

Jack

@MacJack

Good that you took the time / effort to check and see how your JL behaves.. This way, no rude awakening for you, thanks to a no start situation.

Reality is, the only way anyone that has a 2018 JL/JLU can absolutely know, is to do as you did and test...

Personally, I would not believe it, if the dealer told me TSB 18-092-19 had been done on my vehicle in the past.... They will often tell you, whatever, just to pacify you.. I'd still do as you did, and verify how exactly my vehicle behaves..

 

[Gee-pah]

I'd like to know what condition(s) cause the 3.6L to prematurely end an ESS event while you're just sitting at a stop light.

I'd presume it would be voltage and maybe some other thing(s).

I'm not talking about situations where the operator does something while sitting at a stop light that ends an ESS event in the same way it never would have started, like perhaps turning the wheel sufficiently in one direction, or throwing an automatic into a manual gear.

And that said, I'd like one of the aftermarket CANBUS, etc. product makers (JScan, Z Automotive), if possible, to be able to allow the user to customize the voltage at which ESS events end prematurely.

I might consider upping that threshold and running with one big battery.

 

[WranglerMan]

I do know that if you do nothing right at 5 mins ESS ends and engine starts and that is apparently programmed into the logic, have not ran ESS in over a year and never give it much thought anymore and my SSS module sits quietly under the dash doing its thing and my dual battery setup is doing its things and Jscan parts on the way and then TPMS will be taken care of along with several other things

 

[mazeppa]

I used @Rhinebeck01 picture as a reference.

I'm in the process of doing a variation of @Jebiruph "ESS Dual Battery Management" on my 2021 3.6L Gladiator. Just noticed the body ground lead-end and the aux battery ground lead-end are are swapped on my Gladiator. Where the lead-end in Rhinebeck01 photo attached to the main battery on my Gladiator is the aux battery ground, and the small lead-end attached to the isolator switch is the body ground. Found this out after I already duplicated Jebiruph isolator switch, minor setback going to have make some changes to accommodate the the reversed lead-ends.

 

[Jebiruph]

I used @Rhinebeck01 picture as a reference.

I'm in the process of doing a variation of @Jebiruph "ESS Dual Battery Management" on my 2021 3.6L Gladiator. Just noticed the body ground lead-end and the aux battery ground lead-end are are swapped on my Gladiator. Where the lead-end in Rhinebeck01 photo attached to the main battery on my Gladiator is the aux battery ground, and the small lead-end attached to the isolator switch is the body ground. Found this out after I already duplicated Jebiruph isolator switch, minor setback going to have make some changes to accommodate the the reversed lead-ends.

I pretty sure the wiring on my Gladiator is the same as my Wrangler.

 

[mazeppa]

My 2021 Gladiator (built 1:00 AM, Wed. 11 Nov, 2020) is as I described. Verified this 3-4 times, because I was initially confused when when referencing this thread on how you built and hooked up your isolator switch.

This is my current switch configuration, as of this evening.

Edit:
The cable on the IBS labeled "Body Grnd" appears to be a larger gauge then the cable labeled "Aux Neg"

 

[Jebiruph]

My 2021 Gladiator (built 1:00 AM, Wed. 11 Nov, 2020) is as I described. Verified this 3-4 times, because I was initially confused when when referencing this thread on how you built and hooked up your isolator switch.

This is my current switch configuration, as of this evening.

Edit:
The cable on the IBS labeled "Body Grnd" appears to be a larger gauge then the cable labeled "Aux Neg"

Your ground cables are swapped from what mine are. On both my JL and JT, the cable you marked as aux neg is the body gnd. How did you check them?

 

[mazeppa]

Your ground cables are swapped from what mine are. On both my JL and JT, the cable you marked as aux neg is the body gnd. How did you check them?

Note: voltages measurements are high because two different battery chargers were just disconnected from both batteries that were hooked up to their own unique battery charger.




Measuring aux battery voltage, the body ground lead is disconnected from the body (orange circle) and from the main battery. This body ground lead is different from a few random samples of various year models of other JLs/JTs I have recently checked.

Main battery voltage.

0 volts between main + and disconnected body ground lead, same reading when the black lead was on the body ground lug (orange circle.)

Not pictured, but between the body ground lead that my black clip is on and the body ground strap that is disconnected (orange circle) measured zero ohms (100% continuity.)

 

[mazeppa]

Finished (for now. )




I used a second battery disconnect switch with an inline fuse (of debatable size) as the ESS Aux Battery Bypass, so I can manually open/close the circuit and leave the fuse intact. Most toggle switches are not high enough amp rated for me to to have faith in as the bypass switch, the battery disconnect switch exceeds the amp rating needed.

Edit: I was initially debating either to use a bypass switch or just unplug the controlling circuit lead to the power control relay.

 

[Jebiruph]

Based on what @mazeppa found with his battery cables, I had to go recheck my JT and confirmed that my battery cables are different than mazeppa's. Both of ours have the thicker cable is the body ground and it's just the ends of the cables that are switched.

My first thought was that his battery cable was probably built on a Friday during lunch hour, but now I think it's an engineering change. With mazeppa's cables, you only have 1 cable to disconnect at the battery to separate both batteries from body ground. With my cables, you have to disconnect both cables to separate both batteries from body ground.


If you own a 2021 JL/JT, check the negative battery cables to see if the thicker cable is the one with the hole and the stud or just the hole.

 

[Jebiruph]

I thought I'd post a picture and info on some of the different battery switches I've acquired while working on this project.

The top left switch is a dual battery switch rated for 900A cranking (30 sec), 500A (5 min) and 300A continuous.
https://www.amazon.com/gp/product/B0070YEEI8/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1

The bottom left switch is single battery switch rated for 1250A cranking, 455A intermittent and 275A continuous.
https://www.amazon.com/gp/product/B07XTDSD4B/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

The bottom right switch is a single battery switch rated for 300A.
https://www.amazon.com/gp/product/B082W24S4F/ref=ppx_yo_dt_b_asin_title_o07_s00?ie=UTF8&psc=1

The top right switch is a battery switch rated for 75A intermittent and 50A continuous.
https://www.amazon.com/gp/product/B08612YVG9/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

[Jebiruph]

There have been occasional reports of the High Current 150A ESS fuse blowing. The aux battery gets charged by the alternator through this fuse and when it blows, the aux battery will eventual lose it's charge and the internal electronics will go dead along with it. The fuse gets blown when the main battery positive terminal is disconnect from the main battery and makes contact with ground while the aux battery is still connected.

I've been trying to come up with a low cost emergency replacement 150A fused jumper. After an initial order resulted in a very large 150A fuse, I found these reasonably sized 150A fuses. https://www.amazon.com/gp/product/B00W5SGJE6/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

Here's what the fuse looks like with a 6 AWG cable lug attached by a 10-24 3/8" bolt. This is as far as I've got so far, I'm still working on how to cover the bolts so they don't short out while still maintaining visibility to the fuse and access to the bolts. My current thought is to use shrink tubing, but not shrinking it down over the bolts so it can be peeled back when needed.

 

[Jebiruph]

Back at post #11, @JeepScares proposed a circuit to monitor both batteries with a single meter using a DTSP switch. I got a DTSP switch mounted on the meter housing. Now I need to decide if I want to use eyelets or alligator clips for the electrical connections to the battery cables.

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