Auxiliary battery delete problems

[alphawolff]

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.

I'm going to say you're in the 1% here. Very nice luck managing 3 years out of them while using S/S. Normally you get about 2 years or so.

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[dudecw]

@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.

Thanks for all the info. I just pulled F42. I’ll see if it’s back to normal in the morning. I also run a tazer for turning off the ESS and lots of other features so we should be good.

 

[AndySpill]

Thanks for all the info. I just pulled F42. I’ll see if it’s back to normal in the morning. I also run a tazer for turning off the ESS and lots of other features so we should be good.

If it is not back to normal in the morning, and I suspect it will be, the first place I'd look is at my main battery, and getting it load tested.

 

[rk911]

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

One new issue…been doing some additional reading about this.

I have the E-Torque engine and saw conflicting posts. One stated that my JL does not have an aux battery and other stating the JL does have an aux but no accessible black ground cable. I’ll pop my hood in the morning to see what’s what but does having the E-Torque engine change anything regarding disconnecting the aux battery?

 

[dchemphill1]

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.

ESS will function even if you remove the AUX battery and take out fuse 42. It will just do so using the main battery. Most other vehicles on the road today use ESS and just the main battery. JEEP seems to have the ESS wrapped in to the system so it is difficult to isolate just ESS.

 

[Bearded_Dragon]

Reasons for keeping the Aux battery.
...
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.

This did not work for me. My 2018 Wrangler sits 99.9% of the time (put less than 3000 miles in three years) connected to a battery tender and I still had both batteries replaced under warranty. I disconnected the aux after they replaced the batteries and so far so good...

 

[jludave]

does having the E-Torque engine change anything regarding disconnecting the aux battery?

You don't have a standard AUX battery. E-Torque has a 48v AUX battery. The standard AUX battery bypass does not apply to you.

 

[five9dak]

I see a lot of mentions of insulating a hot positive cable during the removal of the aux battery.

Does anyone have a real solution that is not a fire hazard?

I am not driving around with a large gauge battery connected hot wire.

Pairing down the cable assembly, a replacement cable, etc? I have made up battery cables for my hot rod vehicles, its not a big deal with solder terminals.

 

[jludave]

I see a lot of mentions of insulating a hot positive cable during the removal of the aux battery.

I believe that refers to making sure nothing touches the positive side of the battery when bypassing/removing the aux battery.

There no need to do anything else in terms of insulating the positive cable.

 

[five9dak]

I believe that refers to making sure nothing touches the positive side of the battery when bypassing/removing the aux battery.

There no need to do anything else in terms of insulating the positive cable.

I think the cable is hot always because it is intended to bridge the 2 batteries under normal use, so it has voltage from the main.

 

[AndySpill]

This did not work for me. My 2018 Wrangler sits 99.9% of the time (put less than 3000 miles in three years) connected to a battery tender and I still had both batteries replaced under warranty. I disconnected the aux after they replaced the batteries and so far so good...

I respect your thoughts and am sorry for your bad outcome.

The greatest battery charger I can buy won't work on defective batteries. The JL factory ones, sadly, had too many incidents of such battery problems for my comfort level, and too many batteries today are being built IMHO with "built in obsolescence."

Of course this adage is in its final analysis is self destructive but "the less batteries you have in parallel the less chance that one will take the other battery/ies out." And it is so because you do of course need at least one battery.

Lastly, your story is a testament to my belief that if you are not running ESS events, statistically speaking, you have better odds disconnecting the Aux battery, turning ESS off, and pulling Fuse 42 and/or fused-jumpering terminals N1 and N2 in the PDC.

(Full disclosure: I run both batteries, trickle charge, and permit ESS events. That's just me.)

The jumpering was both technique's inventor's Jebiruph's first foray into disconnecting the ESS battery. Bth techniques effectively accomplish the same thing: never allowing the ESS battery cables to be isolated. The jumper overrides the Power Control Relay's separating the batteries when it is energized, and pulling Fuse 42 prevents that energization in the first place.

Effecting both techniques would be redundant but not wrong.

 

[dudecw]

Reporting back. Started the jeep this morning and all is back to normal. Pulling the fuse did the trick. Only one button push to start. Infotainment system worked as normal. ESS was still in off status due to tazer.

The aux battery never caused me any issues and at this point there is no difference in function for me at all. The reason for me to delete it was purely a preventative measure. I have heard of people losing the main battery due to the aux battery dying and killing the main in the process. I just didn’t want that potential situation to leave me stranded somewhere.

 

[AndySpill]

Reporting back. Started the jeep this morning and all is back to normal. Pulling the fuse did the trick. Only one button push to start. Infotainment system worked as normal. ESS was still in off status due to tazer.

The aux battery never caused me any issues and at this point there is no difference in function for me at all. The reason for me to delete it was purely a preventative measure. I have heard of people losing the main battery due to the aux battery dying and killing the main in the process. I just didn’t want that potential situation to leave me stranded somewhere.

...the "textbook logic" for doing what you did IMHO if you're not running ESS events.

Why keep connected a battery you don't need (i.e. if you're not running ESS events)? It's failure if connected the main battery can effect that battery. And while sure, it's possible for a bad main battery to negatively effect an ESS battery, you need the main battery.

Connecting batteries in parallel is not, for example, like connecting many other things, like...I don't know...water pumps together. In the latter example if a pump fails the others that are operational work harder. With batteries in parallel...well..it's like the Borg for all you Trekkies.

The strengths of a pairing up of individual things as a group comes with the downside that one failing individual thing can negatively affect the others.

 

[andy29847]

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.

It is ironic that you continue to try and sell this scenario given the number of problems people have with the stock 2 battery configuration.

 

[Heimkehr]

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).

Yes. ? The OEM ESS battery remains in situ, but the related functioning is turned off via a defeat harness. When the main battery requires replacement, I'll either isolate the small battery (fuse F42, etc.), or more likely, remove it.

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