Auto start stop

[TheNewGuy]

So me personally I purchased the auxiliary battery/tow system not because I plan on towing, but because having the auxiliary battery system is really nice. I already currently have three items tied into it. Aux 1, 2, and 3.
I don't know about in other states, but in Texas batteries tend to last about 3 years before they start having issues. I know it will cost a little more, but I plan on replacing both batteries at the same time. It's probably going to cost me about $600 because I'm not going to skimp on battery cost. I'm going to go for some top-of-the-line stuff. But if you have any intention on using the auxiliary battery and/or the auxiliary buttons (Personally I think they're extremely handy) I wouldn't get rid of it.

For $100 you can get something that will remember your choice every time you start the vehicle. I don't see why you do away with such a useful thing like an auxiliary battery. If you have no intention of ever adding any other electronics to the Wrangler, I guess it makes sense.

I don't know, for me whe whole reason I bought my Wrangler was to modify it. Aux 1 is my Dixie Horn, aux 2 is my light bar, aux 3 Is two front universal attachment points. (I haven't rigged it up yet but) aux 4 will be two rear universal attachment points. Plug and play is extremely valuable to me.

The diesel comes with the AUX battery whether you have the tow package or not. The AUX Switches come with the tow package. If you don't get the tow package you don't have the aux switches.
The ESS system is a poor design and a PITA when the AUX dies. At least its more easily accessible on the diesel.
Many people don't use ESS and don't have the AUX switches so really no need for that battery.
I haven't done away with the AUX battery. The SmartStopStart just makes the button a smart button so it remembers the previous setting when the JL was turned off.

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[dchemphill1]

Go with the jumperless bypass. Pull fuse F42 and disconnect the aux battery negative terminal from the main terminal and you're all set.

https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

Except start stop will run off the main battery

 

[swampflyer]

Why can’t the computer be reprogrammed to eliminate stop start?? Surely there is a computer geek out there that can do this.

 

[Deleted User 38384]

The diesel comes with the AUX battery whether you have the tow package or not.

Is that true? This is the first time I've ever heard that.

When I did my factory order I was under the impression that the auxiliary battery was tied into the auxiliary switches. I mean the auxiliary button wire tie-ins in the engine bay even go down to the auxiliary battery.

Most cars with start stop features use bigger more powerful batteries that will handle the increased electricity use of the start stop system. My wife's Subaru is like that, it has a $280 battery because of the automatic start stop system.

I'm guessing FCA didn't want to put in a bigger battery and just decided to put in two smaller batteries?

That's very strange. I'm going to have to read more into this. Appreciate the heads up!

 

[Ratbert]

Is that true? This is the first time I've ever heard that.

When I did my factory order I was under the impression that the auxiliary battery was tied into the auxiliary switches. I mean the auxiliary button wire tie-ins in the engine bay even go down to the auxiliary battery.

Most cars with start stop features use bigger more powerful batteries that will handle the increased electricity use of the start stop system. My wife's Subaru is like that, it has a $280 battery because of the automatic start stop system.

I'm guessing FCA didn't want to put in a bigger battery and just decided to put in two smaller batteries?

That's very strange. I'm going to have to read more into this. Appreciate the heads up!

Yep, the aux battery and the tow package are unrelated options.

 

[Deleted User 38384]

Yep, the aux battery and the tow package are unrelated options.

Well that settles that! ?

 

[jeepoch]

The AUX battery powers nearly everything in the cabin, lights, fans and accessories when ESS is active. It powers nothing when not. The alternator (or generator with eTorque), provides power when the engine is running. However, both batteries are always drawing charging current when the alternator or generator is supplying power. The extent of which is mostly determined by the Intelligent Battery Sensor (IBS) as managed by the Engine Control Module (ECM).

Regardless, having two dissimilar size batteries connected in parallel is absolutely the most asinine design anyone could of come up with. The FCA engineering team and the management which approved it should have their automotive development certification badges revoked. Bad idea plain and simple.

The charging (and discharging) characteristics of each battery are totally separate and distinct. Each battery has it's own power demands and timing personalities. Each left to their own circuit would behave differently. Yet when connected in parallel, they are both being managed as if they are a single larger battery. So the decisions of the ECM in producing an appropriate level and rate of charge is inherently wrong for both. This is best case.

In addition, their capacity decay characteristics will also be different, especially depending on loading and battery conditioning over time. Each battery will tend to 'age' differently because they have different usages. The Main mostly for cranking and the AUX for powering accessory circuits during ESS.

This all works towards pretty much an unpredictable outcome of when each battery will degrade to the point when it needs to be replaced. While some say when one goes replace them both. This is certainly not the case and if nothing else is the most expensive (but still likely the most reliable) of overall maintenance strategies. However, the main will still likely be completely within it's nominal operating lifecycle range when the smaller AUX does die. Of course, defective cells in either battery can happen in any particular vehicle's day-to-day travels.

So this ESS design is just impossible to predict an accurate replacement schedule. It practically forces you into a 'run until failure' operating mode. This is exactly what Jeepers want to avoid, being 'stranded in the middle of nowhere'. So what in the world was FCA thinking?

Of course in reality they were likely under the gun with mandatory CAFE and Carbon Credit pressures to do something very quickly within their 2018 Model Year program release timing. Unfortunately, once implemented it would remain that way until the next program refresh opportunity. The eTorque and 4xe in the meantime has certainly given them opportunities for improvement. Maybe this will all get resolved with the JM release.

But it matters not when trying to formulate a strategy for replacement. Your guess is as good as anyone's.

Best of luck.
Jay

 

[jludave]

Except start stop will run off the main battery

I have a Tazer to disable it. There are other devices that can as well.

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