Stop/start revisited. Need clarification.

[Steph1]

Folks,

A few years ago, after getting frustrated of the stop/start not working, I installed an underhood charger to keep the batteries in top shape. I’d plug the jeep a few times a week and the stop/start was working perfectly.

Fast forward to last summer where I noticed that the stop/start would work upon the first stop and then wouldn’t for the rest of that commute. Upon returning, it would again work on the first stop and wouldn’t work again on that commute.

I recently decided to look into it again and realized that after that first stop where the stop/start would work as designed, it would then automatically get on the “battery protection mode”. It does that now on every commute. Works the first time and then “battery protection mode”. Same thing on my way back !!!

Now…

1- If the batteries needed to be changed, stop/start wouldn’t work as designed at the first stop of every commute.

2- I do not wish to bypass stop/start as I like everything that is supposed to work to operate normally.

3- I changed the battery sensor thinking that it was the culprit, but nope

4- What adds to the frustration is that my girlfriend and daughter both drive Bronco Sports and their stop/start work absolutely flawlessly

So to those that have battled and won on that topic, what would explain what is going on ???

I insist that I do not wish to cancel stop/start or bypass batteries at this point.

Thanks

Pic for attention.

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[Riverjeep]

I do know there are certain parameters where the start stop will not work such as the use of max ac and perhaps other things you may turn on in your commute. I would play around and turn everything off such as heat and heated seats and such just before coming to a stop and see if it again works Also keep in mind if you don't press the brake peddle hard enough it will not engage. Lastly don't know how old your batteries are but that could be an issue, the smaller battery especially.

 

[Ratbert]

Have the dealership figure out what's wrong? You paid for that warranty.

 

[Maverick909]

cabin temp vs what the Drive input is asking. If cooling cabin, no start stop. if heating cabin, no start stop, Low battery voltage/ charging No stop start. ( and for the manuals you have to be in neutral and off the clutch pedal) also brake pressure switch is also part of the system too.


My stop start didnt like working unless i was driving longer than an hour then it would enable. I ended up doing the Genises dual battery setup and its worked ever since thus i hate it and find it utterly useless and a waste of wear on the motor and starter for .11 MPG gain on avg a tank. I save the fuel and emissions by driving easy and in the slow lane.

 

[NWJeepr]

When was the last time you changed your batteries? You mentioned you started this a few years ago. Batteries typically only last a few years, shorter in very hot and very cold climates.

Leaving both batteries disconnected, charging them, and then re-connecting recently cleared a stop/start error for me. Batteries both tested great, and the error hasn't come back since.

 

[jellis4148]

How old are the batteries? I can say with 99% assurance you need to replace them.

 

[WranglerMan]

I would say have the batteries tested, my bet is they are bad, the reason ESS likely works on the first event is because the batteries have been recently charged but after its gone thru the one ESS event they don't have enough power and you mentioned that the EVIC displays “ battery charging” this is a good indication you have battery issues.

 

[Old Dogger]

Have your Batteries load tested.

 

[Jeep Wick]

I disabled mine, but I remember something as simple as turning the steering wheel would prevent it from working. I imagine you are also using the heat now and that may be keeping your engine on.

 

[Terrymo]

Warning information overload. You are probably already aware but just in case. There are so many possible reasons listed in the owners manual.

POSSIBLE REASONS THE ENGINE DOES NOT AUTOSTOP Prior to engine shut down, the system will check many safety and comfort conditions to see if they are fulfilled. Detailed information about the operation of the Stop/Start system may be viewed in the instrument cluster display Stop/Start Screen. Situations when the engine will not stop include (but not limited to):  Driver’s seat belt is not buckled.  Driver’s door is not closed.  Battery temperature is too warm or cold.  Battery charge is low.  Cabin heating or cooling is in process and an acceptable cabin temperature has not been achieved.  Gear selector is in MANUAL (M) mode.  HVAC is set to full defrost mode at a high blower speed.  HVAC is set to MAX A/C.  Engine has not reached normal operating temperature.  Engine or exhaust temperature is too high.  The transmission is not in a forward gear.  Hood is open.  Transfer case is in 4L or N (Neutral).  Brake pedal is not pressed with sufficient pressure.  Accelerator pedal input.  Vehicle speed threshold has not been achieved from previous Autostop.  Steering angle is beyond threshold (ESS Models Only).  ACC is on and speed is set.  Vehicle is at high altitude.  System fault is present. It may be possible for the vehicle to be driven several times without the Stop/Start system going into a STOP/START READY state under more extreme conditions of the items listed above. TO START THE ENGINE WHILE IN AUTOSTOP MODE While in a forward gear, the engine will start when the brake pedal is released or the throttle pedal is pressed. The transmission will automatically re-engage upon engine restart. Conditions That Will Cause The Engine To Start Automatically While In Autostop Mode:  The transmission selector is moved out of DRIVE.  To maintain cabin temperature comfort.  Actual cabin temperature is significantly different than temperature set on Auto HVAC.  HVAC is set to full defrost mode.  HVAC system temperature or fan speed is manually adjusted higher.  Battery voltage drops too low.  Stop/Start OFF switch is pushed.  A Stop/Start system error occurs.  Stop/Start Autostop Active time exceeds five minutes.  Transfer case is in 4L or N (Neutral).  Steering wheel is turned beyond threshold (ESS Models Only).

 

[Ratbert]

Warning information overload. You are probably already aware but just in case. There are so many possible reasons listed in the owners manual.

POSSIBLE REASONS THE ENGINE DOES NOT AUTOSTOP Prior to engine shut down, the system will check many safety and comfort conditions to see if they are fulfilled. Detailed information about the operation of the Stop/Start system may be viewed in the instrument cluster display Stop/Start Screen. Situations when the engine will not stop include (but not limited to):  Driver’s seat belt is not buckled.  Driver’s door is not closed.  Battery temperature is too warm or cold.  Battery charge is low.  Cabin heating or cooling is in process and an acceptable cabin temperature has not been achieved.  Gear selector is in MANUAL (M) mode.  HVAC is set to full defrost mode at a high blower speed.  HVAC is set to MAX A/C.  Engine has not reached normal operating temperature.  Engine or exhaust temperature is too high.  The transmission is not in a forward gear.  Hood is open.  Transfer case is in 4L or N (Neutral).  Brake pedal is not pressed with sufficient pressure.  Accelerator pedal input.  Vehicle speed threshold has not been achieved from previous Autostop.  Steering angle is beyond threshold (ESS Models Only).  ACC is on and speed is set.  Vehicle is at high altitude.  System fault is present. It may be possible for the vehicle to be driven several times without the Stop/Start system going into a STOP/START READY state under more extreme conditions of the items listed above. TO START THE ENGINE WHILE IN AUTOSTOP MODE While in a forward gear, the engine will start when the brake pedal is released or the throttle pedal is pressed. The transmission will automatically re-engage upon engine restart. Conditions That Will Cause The Engine To Start Automatically While In Autostop Mode:  The transmission selector is moved out of DRIVE.  To maintain cabin temperature comfort.  Actual cabin temperature is significantly different than temperature set on Auto HVAC.  HVAC is set to full defrost mode.  HVAC system temperature or fan speed is manually adjusted higher.  Battery voltage drops too low.  Stop/Start OFF switch is pushed.  A Stop/Start system error occurs.  Stop/Start Autostop Active time exceeds five minutes.  Transfer case is in 4L or N (Neutral).  Steering wheel is turned beyond threshold (ESS Models Only).

And that completely neglects the common scenarios typically mentioned here, unless "system fault is present" is all encompassing for any other anomaly.

 

[Terrymo]

And that completely neglects the common scenarios typically mentioned here, unless "system fault is present" is all encompassing for any other anomaly.

I plead ignorance. I was just hoping the OP would see something on the list that made sense in his scenario.

 

[AndySpill]

Folks,

A few years ago, after getting frustrated of the stop/start not working, I installed an underhood charger to keep the batteries in top shape. I’d plug the jeep a few times a week and the stop/start was working perfectly.

The charger was connected to the positive and negative terminals of the main battery, correct? This would charge both batteries while the vehicle is parked.

Fast forward to last summer where I noticed that the stop/start would work upon the first stop and then wouldn’t for the rest of that commute. Upon returning, it would again work on the first stop and wouldn’t work again on that commute.

I recently decided to look into it again and realized that after that first stop where the stop/start would work as designed, it would then automatically get on the “battery protection mode”. It does that now on every commute. Works the first time and then “battery protection mode”. Same thing on my way back !!!

Now…

1- If the batteries needed to be changed, stop/start wouldn’t work as designed at the first stop of every commute.

..or the age of the batteries and/or defect might prevent either or both batteries from [quickly enough] accepting back charge from the alternator such that all you get out of the system is one ESS event.

As many have said, time to load test those batteries individually.

To do so, temporarily remove the black cable from the main battery's negative post whose distal end is NOT the body ground. Position this loose cable away from any metal.

Place the load test on the main battery's posts. This will test only the main battery.

Now move the load tester's negative lead to the dangling cable. This will test the ESS battery...yes, even as the positive side of the load tester remains on the positive post of the main battery. (The only circuit your closing here is with the ESS battery. That loose cable has as its distal end the negative post of the ESS battery.)

Make sure to reattach that cable.

If you need replace either or both batteries replace both. For your main battery get a group H7 battery even if your JL came with a smaller H6. It will fit, although you will have to remove a cleat in the battery tray if you've had H6 batteries up until now.

4- What adds to the frustration is that my girlfriend and daughter both drive Bronco Sports and their stop/start work absolutely flawlessly

So to those that have battled and won on that topic, what would explain what is going on ???

The anecdote here, not documented, is that in dual AGM JL original testing prior to release the entertainment system's electronics proved too sensitive to voltage drops that a single battery might experience. IMHO this might call for Stellantis to have pushed back on the vendor for this system, in all its flavors, to build a less sensitive system. Instead the dual battery system was implemented with two dissimilar size, albeit identical voltage and chemistry batteries in parallel.

Battery purists would argue that each battery should have been the same size (in addition to the same voltage and chemistry requirement) and that each play the role of main and aux battery, switching off.

Putting batteries in parallel, which yours are but for an instant at cold crank when the ESS battery is tested, and during ESS events, can cause a failing battery to cannibalize the other: such the impetus for swapping out both of you want to maintain ESS function.

If you are at a crossroad right now for buying new batteries you might want to consider Genesis Offroad's Stock Battery Replacement kit, but it's installation and addition cost isn't for all.

https://www.genesisoffroad.com/products/2018-jeep-jl-jt-stock-battery-replacement-kit_p_295

I insist that I do not wish to cancel stop/start or bypass batteries at this point.

Thanks

Pic for attention.

 

[Steph1]

I do know there are certain parameters where the start stop will not work such as the use of max ac and perhaps other things you may turn on in your commute. I would play around and turn everything off such as heat and heated seats and such just before coming to a stop and see if it again works Also keep in mind if you don't press the brake peddle hard enough it will not engage. Lastly don't know how old your batteries are but that could be an issue, the smaller battery especially.

Thanks, fully aware of your suggestions. I did try with nothing on etc….. always falls on battery protection mode after the first successful stop/start

 

[Steph1]

When was the last time you changed your batteries? You mentioned you started this a few years ago. Batteries typically only last a few years, shorter in very hot and very cold climates.

Leaving both batteries disconnected, charging them, and then re-connecting recently cleared a stop/start error for me. Batteries both tested great, and the error hasn't come back since.

Something to consider, thank you

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