Auxiliary battery delete problems

[dudecw]

I was installing some aftermarket inner fenders and thought I would take care of the auxiliary auto start stop battery while I had easy access. I pulled out the batteries and traced the cables. Ne negative went straight to the negative terminal on the main battery and the positive went up to the terminals on the side of the fuse box and then in another direction down to something below. I pulled out the negative entirely but just taped up the positive and left it in place. For the most part everything works just fine. I don't have any warning lights on the dash. The odd thing is, when I go to start the Jeep for the first time for the day it acts like I have disconnected the battery and then hooked it back up. When I push the start button it goes to "run" on the button but doesn't start the engine, I have to push it one more time. Also the big warning shown up on the center 12" display and I have to agree to whatever the terms are. I don't remember seeing that every time I started it before. If I park it for a moment and then hop back in after a short time like an hour or so, those things don't happen.

Anyone else see any of these issues when disconnecting the little battery? This is on a 2024 if that makes any difference.

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[Gregj]

Did you pull fuse F42? That is the second part of the auxiliary battery delete.

Gregj

Edit to add here is the thread that explains the process.
https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

 

[AndySpill]

@Gregj told you what to do; I'll tell you why.

When your dual AGM battery JL attempts a cold crank, prior to this it, using circuit 42, energizes the Power Control Relay (PCR) to attempt to separate the two batteries so as to test the Aux battery (that you have pulled) in isolation.

Because you have pulled it the test fails. Be glad you don't have an early 2018. Your actions would have stranded the vehicle.

In later model 2018's and beyond the start logic was changed that if this test fails, the subsequent crank is effected only against the main battery, and if successful, the ESS system is turned off by the vehicle.

By additionally pulling Fuse 42 you prevent the PCR from energizing and the batteries from being separated. Now, all calls to test just the ESS battery prior to cold crank now go to all available batteries, of which you only have left the main, which you have "tricked" your JL into thinking, for purposes of this test, is the ESS battery.

Your vehicle, with this Fuse 42 pull, unlike currently, will be none the wiser as to the absence of the ESS battery. If you don't turn ESS off with the button, or aftermarket tech the vehicle will be glad to run ESS events on the one main battery.

Countless other vehicle manufactuers run ESS this way, with one battery, but the "perfect storm" of a cold night, a long traffic light for an ESS event to occur in, a main battery "on its way out," and one too many aftermarket accessories drawing power (as are common for Wrangler owners) could, in theory, deplete the main battery of sufficient power that by the time its voltage drops low enough for your vehicle to early terminate the ESS event, inadequate power lies in this battery to effect the engine crank.

So do please in addition to the Fuse 42 pull, turn ESS off.

 

[rk911]

Andy, thanks for that great, detailed explanation. I have an after-market device that has permanently disabled the auto start-stop. The only after-market devices I plan on installing are a dual-band ham radio mobile and, possibly, a dash-cam only powered when the engine is running.

But, I'd like to hear a reasonable argument against permanently removing the aux battery altogether. I take meticulous care of our vehicles which includes testing the state of the battery. Not terribly concerned being stranded with a dead battery. And, if need be, I can upgrade the 'primary' battery.

 

[dchemphill1]

Been running without the AuX battery for 2 years. No issues. I did use jscan to aid in the process but even that has you disconnecting a hood switch which also takes out remote start. I did not care. I have lived more years without remote start than ever having it. Besides the Jeep heats up super fast!

 

[rk911]

Been running without the AuX battery for 2 years. No issues. I did use jscan to aid in the process but even that has you disconnecting a hood switch which also takes out remote start. I did not care. I have lived more years without remote start than ever having it. Besides the Jeep heats up super fast!

Please help me out here. Are you saying that *disconnecting* the aux battery as reported in Andy's post eliminates remote start or *removing* the aux battery eliminates remote start? I love the remote start and have been using it a lot this past winter and would not want to lose it but I'm not seeing what one thing has to do with the other.

 

[Rhinebeck01]

Please help me out here. Are you saying that *disconnecting* the aux battery as reported in Andy's post eliminates remote start or *removing* the aux battery eliminates remote start? I love the remote start and have been using it a lot this past winter and would not want to lose it but I'm not seeing what one thing has to do with the other.

@rk911

When you bypass the Aux battery or delete the Aux battery, you do not lose remote start..

Also, ESS still works.. when running with just the Main.

That mention of no more remote start was a guy talking that he used the very lame, used by few, very laughable JSCAN hack to deal with ESS versus the much wiser move.... and that is to buy an adjunct that in essence does the ESS button push for you.

.

 

[rk911]

@rk911

When you bypass the Aux battery or delete the Aux battery, you do not lose remote start..

Also, ESS still works.. when running with just the Main.

That mention of no more remote start was a guy talking that he used the very lame, used by few, very laughable JSCAN hack to deal with ESS versus the much wiser move.... and that is to buy an adjunct that in essence does the ESS button push for you.

.

Ah, OK. I use this to permanently disable the Auto Start/Stop. Many thanks.

 

[Rhinebeck01]

Ah, OK. I use this to permanently disable the Auto Start/Stop. Many thanks.

@rk911

I personally would not use that particular offering if you gave it to me for free...

I know a few that installed one of those knockoffs and it hiccuped occasionally and then eventually just died and stopped working altogether..

I suggest guys go with the SmartStopStart offering that forum members here have used since 2018..
Smaller foot print and never ever any issues reported in regard to that offering..

Anyway, when running with just the Main, do limit the use of ESS. Sure ESS works and no harm using it occasionally but do minimize use of ESS.

Yes, I have been running my 2018 JL with just the Main since early 2019. Never any issues doing so.

.

 

[rk911]

@rk911

I personally would not use that particular offering if you gave it to me for free...

I know a few that installed one of those knockoffs and it hiccuped occasionally and then eventually just died and stopped working altogether..

I suggest guys go with the SmartStopStart offering that forum members here have used since 2018..
Smaller foot print and never ever any issues reported in regard to that offering..

Anyway, when running with just the Main, do limit the use of ESS. Sure ESS works and no harm using it occasionally but do minimize use of ESS.

Yes, I have been running my 2018 JL with just the Main since early 2019. Never any issues doing so.

.

Thanks. I never use ESS...hate it. That's why I purchased the Auto Stop/Start. I leave it in the OFF position. So far, so good. No fault codes, no issues of any sort.

 

[AndySpill]

.. I'd like to hear a reasonable argument against permanently removing the aux battery altogether.

Reasons for keeping the Aux battery.

Of course the primary being 1) you want to run ESS events. With it connected it spares the main battery to effect the bulk of the post ESS event engine cranking (actually both batteries come together in parallel to effect the crank when the ESS event terminates.)

2) You want to keep the battery physically in your vehicle but disconnected at merely the negative terminal of the main battery for emergencies, and running equipment while overlanding, charging it on your own when parked. I think Rhinebeck01 does this FWIW.

3) You regularly trickle charge your batteries anyway as a hedge against this small battery cannibalizing the main battery and don't worry about the Aux battery going bad as much as a result.

I am of the opinion that if not running ESS events the statistical pros of keeping the ESS battery in place, and connected are outweighed by the cons.

But, unlike so many here I don't consider that which I do what others must do as well. My friend here James @Heimkehr turns off ESS but runs with both batteries (last I've checked). I guess if you've got a good Aux battery it does aid in the engine crank.

I've tagged him here so he can offer you his opinions on which you can make an informed decision.

My situation, which BTW need not be yours: different people different use cases is that I already have a roof rack that's rarely used and which I have a solar panel that trickle charges my batteries at rest. I run ESS events and keep both batteries connected. I am rare.

My batteries are going on three years of age, and I have two new ones in the garage I'm ready to swap in on the next not so cold day.

 

[rk911]

Andy, I appreciate your response but none of those situations apply. My trail/overland days are behind me, I can think of no reason why I would want to use or need ESS and I only kept a Battery Minder on our other vehicles when we spent winters in AZ. And those days are, hopefully temporarily, also behind us. I sold our '03 TJ and bought our JL out,of nostalgia and just cuz it's fun to drive.

I do appreciate the time you took to reply. Being an old-er techie-type I do like the electronics in the JL but my TJ was so much simpler. The Aux Battery configuration is klugy but I guess that's progress?

I think what i'll do is disconnect the aux battery's black ground cable (EZ way to tell which cable is which?) and then pull the F42 fuse and see how that goes.

 

[AndySpill]

Please help me out here. Are you saying that *disconnecting* the aux battery as reported in Andy's post eliminates remote start or *removing* the aux battery eliminates remote start? I love the remote start and have been using it a lot this past winter and would not want to lose it but I'm not seeing what one thing has to do with the other.

Rhinebeck01 accurately told you no.

I'll tell you why.

When you take out Fuse 42 and the vehicle is unable to energize the Power Control Relay (PCR), that when supplied electrical current separates the two batteries--(which happens for an instant at cold crank and during ESS events) your JL is completely unaware that circuit 42 has no power and this relay can't function.

It's not as if the vehicle monitors circuit 42, informing the operator of its malfunction.

And when the PCR can't energize the batteries can't be separated. All calls for electrical current now, get--your vehicle completely unaware of this--routed to all connected batteries--if which you only have one.

Since the vehicle sees no problem with this change, there is nothing to warn the remote system to shut down because of this Aux battery/Fuse 42 pull.

It would be one thing if you just disconnected the Aux battery without the Fuse 42 pull.

Any situation that would shut down or conversely let remote start work before the Aux battery and Fuse 42 pull will effect your vehicle exactly the same way. To rephrase this, If remote start should somehow stop working under the Aux battery Fuse 42 pull then it would have also stopped working with all the factory connections left as is, and vice versa.

 

[AndySpill]

Andy, I appreciate your response but none of those situations apply. My trail/overland days are behind me, I can think of no reason why I would want to use or need ESS and I only kept a Battery Minder on our other vehicles when we spent winters in AZ. And those days are, hopefully temporarily, also behind us. I sold our '03 TJ and bought our JL out,of nostalgia and just cuz it's fun to drive.

I do appreciate the time you took to reply. Being an old-er techie-type I do like the electronics in the JL but my TJ was so much simpler. The Aux Battery configuration is klugy but I guess that's progress?

I think what i'll do is disconnect the aux battery's black ground cable (EZ way to tell which cable is which?) and then pull the F42 fuse and see how that goes.

...insulating that lose cable's ends please so it cannot short on any vehicle metal parts and cause you possible trouble...

 

[rk911]

...insulating that lose cable's ends please so it cannot short on any vehicle metal parts and cause you possible trouble...

Of course. And yet anothe reason to remove the aux batt.

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