Start/Stop Ready

[RenegadeT]

Bought my 2018 JL used 9months ago with 9kmiles on it. Since I've owned it, the Start/Stop display was showing 'Not Ready', and it never engaged. I read about it here, have been a little worried my aux battery dying soon, but other than that, have really enjoyed not having to hit the OFF button every time I drive (not a fan of start/top function).
So I was at a stop light yesterday with tunes cranking, did not notice it shut off, first realized it when the light turned green and I accelerated, the Jeep fired up! Freaked me out a bit, scrolled thru the menus and found Start/Stop Ready. Sure enough this continued until I hit the OFF button. Several other trips thru the day, the feature is ready and I had to manually shut it off.
This was out of the blue, I did nothing different than I have for the past 9months/6kmiles of driving. Any thoughts on what could be going on here?

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[JeepJLU402]

Mine started working after about a year of not working on my 2019. I have both batteries in my garage to change out tomorrow. So of course last night it all starts working.
I checked the voltage of both after driving last night and they were at 12.5 V. Before I was lucky if the main would be 12.4V and the Aux at 12.2V right after an hour of driving.
The only thing that I noticed was I can watch the voltage drop at an ESS event. 12.4V to 12.1V happens fast then after about 30 secs it hits 11.9V and the Jeep starts back up.

 

[Terpsmandan]

With only 9k on a 2018, pretty sure that the small battery had not had a good charge in a while.

 

[Chupacabra]

Your batteries eventually got enough of a charge to cross the threshold that ESS wants before it starts working. If I let mine sit a while, ESS won't work until I drive quite a bit either.

 

[Reinen]

You never said why ESS is "not ready". It always tells you. If you have AC or heat on and it's actively cooling/heating the cabin ESS will not engage.

 

[Chupacabra]

You never said why ESS is "not ready". It always tells you. If you have AC or heat on and it's actively cooling/heating the cabin ESS will not engage.

Not always. Mine usually just says "Start/Stop Not Ready" without any explanation. Sometimes it might say "Cabin Cooling" or something like that, but generally it just says "Start/Stop Not Ready".

 

[RenegadeT]

Not always. Mine usually just says "Start/Stop Not Ready" without any explanation. Sometimes it might say "Cabin Cooling" or something like that, but generally it just says "Start/Stop Not Ready".

Mine too...I've never seen it tell me why s/s is not ready. Always wondered if PO monkeyed with something to disable it, but my research seemed to indicate that probably wasn't the case.
I guess I can buy the fact that the aux battery never had a full charge. The dealer I bought it from seemed to know the PO, said she had a very short work commute, and then the pandemic happened negating that.

 

[Chupacabra]

Mine too...I've never seen it tell me why s/s is not ready. Always wondered if PO monkeyed with something to disable it, but my research seemed to indicate that probably wasn't the case.
I guess I can buy the fact that the aux battery never had a full charge. The dealer I bought it from seemed to know the PO, said she had a very short work commute, and then the pandemic happened negating that.

I bought mine brand new. ESS worked fine for first year then just quit. I eventually replaced both batteries and it generally works OK now. If it sits for 2-3 days it doesn't always come on right away, but once I drive it enough it mostly works.

If it gets to the point where it doesn't work at all, I've found putting a trickle charger on it overnight will get it to work again for month or more without hesitation.

I still think Jeep/Stallantis needs to re-calibrate the IBS (or whatever decides there is or is not enough juice) to be slightly less touchy. Would probably save a ton of warranty work that does nothing. I've had 3 previous cars with ESS (and only ONE battery in each of them!) and they always worked flawlessly - all the time. This double-battery system is just plain stupid.

 

[RenegadeT]

Figured I would update my thread. I guess the batteries just needed a few months of constant use.
Now 3-4 months later, the start/stop is always working, and I am constantly to shutting it off. The button is literally right next to the shifter, so it’s not that bad.

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