Auto STOP-START Stopped on its Own

BillArnett

New member
I'm still trying to figure out why anyone would run a compressor, a LOT and with the engine off :thinking:

Just to see what would happen. Now I know it’s OK but just barely. I’ll probably not do it regularly. But I’ll feel confident in a pinch.
 

BillyHW

New member
Does that ESS Off light ever come on for any of the reasons listed in the owner's manual for why it might not be working? Otherwise I'd say the light coming on is pretty strange.
 

BillArnett

New member
so if you have the climate controls selected to Auto the auto start stop will not function

I don’t think that’s right. I have the A/C on Auto most of the time and the ESS functions normally. But, as noted in the manual, the ESS will not engage if the cabin is not at or close to the set temperature or if the MAX A/C mode is set. See page 326 of the manual for a LONG list of other conditions.
 

Rellik

Member
I don’t think that’s right. I have the A/C on Auto most of the time and the ESS functions normally. But, as noted in the manual, the ESS will not engage if the cabin is not at or close to the set temperature or if the MAX A/C mode is set. See page 326 of the manual for a LONG list of other conditions.
strange I have max AC mode on yet when auto is selected the ESS doesn't function. As soon as I deselect Auto it starts working...
 

ubbb69

Member
Eddie I am having an issue with auto start also but not sure it is related. Apparently Jeep wants the battery to stay around 12.6v to get as good of fuel mileage as possible. Only below that does it call for charge. When on
A long drive my battery constantly drains and only seems to charge while coasting. I made a video on the way to dealer then he rode around with me for about an hour with his tablet monitoring what the system was calling for and where it was at. It was all up
To
Snuff with what Jeep
Was asking of the charging system. I am not going to start a you tube account to post but I can send it to someone if they will
Post it.
 

BillArnett

New member
Something much more complicated than I’m used to is going on with the JL charging system. Maybe someone here can explain?

What I noticed today: after a few hours of wheeling at Hollister Hills I pumped up my tires again for the trip home (this time with the engine running) and set off on the highway. When I got the the first stop I noticed that the Engine Start/Stop didn’t stop the engine as usual. I checked the status and it said something like “not ready because of battery saving mode”. So I checked the battery voltage and it said 12.7 or 12.6. Oddly (for me anyway) the voltage did NOT increase when in revved up the engine but it did increase to 13.5 or so when I was coasting at zero throttle. This continued all the way home (80 miles). A few house later I drove it around the block and it was back to normal: ESS worked as soon as the engine heated up.

So what’s going on? It seems like it’s not charging the battery most of the time.
 

Tellico

Member
Something much more complicated than I’m used to is going on with the JL charging system. Maybe someone here can explain?

What I noticed today: after a few hours of wheeling at Hollister Hills I pumped up my tires again for the trip home (this time with the engine running) and set off on the highway. When I got the the first stop I noticed that the Engine Start/Stop didn’t stop the engine as usual. I checked the status and it said something like “not ready because of battery saving mode”. So I checked the battery voltage and it said 12.7 or 12.6. Oddly (for me anyway) the voltage did NOT increase when in revved up the engine but it did increase to 13.5 or so when I was coasting at zero throttle. This continued all the way home (80 miles). A few house later I drove it around the block and it was back to normal: ESS worked as soon as the engine heated up.

So what’s going on? It seems like it’s not charging the battery most of the time.

Sounds like you worked the battery past normal duty when using the compressor and it took a little time to get happy again. Once it was back to normal, it allowed the start/stop function to operate again.

Just curious; do you still have the stock battery, and do you have the HD electrical package?
 

ubbb69

Member
Something much more complicated than I’m used to is going on with the JL charging system. Maybe someone here can explain?

What I noticed today: after a few hours of wheeling at Hollister Hills I pumped up my tires again for the trip home (this time with the engine running) and set off on the highway. When I got the the first stop I noticed that the Engine Start/Stop didn’t stop the engine as usual. I checked the status and it said something like “not ready because of battery saving mode”. So I checked the battery voltage and it said 12.7 or 12.6. Oddly (for me anyway) the voltage did NOT increase when in revved up the engine but it did increase to 13.5 or so when I was coasting at zero throttle. This continued all the way home (80 miles). A few house later I drove it around the block and it was back to normal: ESS worked as soon as the engine heated up.

So what’s going on? It seems like it’s not charging the battery most of the time.
This is the same issue I was having. It is exactly how Jeep designed the charging system though. It is designed to put as little load as possible on the system for fuel conservation.
 

doubletapdaddy

Caught the Bug
So what's the problem? A fully charged battery is 12.6/12.7 volts or above. Maybe instead of just removing Offroad Pages they should remove everything so everybody can chill out.
Edit - "LOL" added for levity.
 

Last edited:

13_gecko_rubi

New member
It's working exactly like it's supposed to. Voltage is not the best way to determine if a battery is fully charged. The JL (and most new vehicles) all have complicated state of charge algorithms watching amp hour draw and amp hour input into the battery. Look at your negative battery terminal and you will see the current sensors which are used to determine battery state of charge. If it sees a load on the battery it will increase the current out of alt by increasing voltage as that's the only variable on an alternator.

Sent via....
 

13_gecko_rubi

New member
So what's the problem? A fully charged battery is 12.6/12.7 volts or above. Maybe instead of just removing Offroad Pages they should remove EVERYTHING so everybody can chill out.
I agree. Showing info usually causes more bad than good. When the digital gauges were added to the JK in 13/14 It caused huge warranty spikes because people saw the higher water temps which were actually normal for the 3.6 and took them in for overheating even though the physical gauge showed right in middle and no lights, codes etc. Your vehicle will tell you if something is wrong :)

Sent via....
 

ubbb69

Member
Problem is that on long drives my auto start will not even kick in as it states the voltage is to low. This happens around 12.4 and when I go long streatches without coasting. I am fine with it as it is designed that way. But at that time it had me concerned as I am used to 14.1 while motor is running. Edited to ask if you guys even read the above statements.
 

Last edited:

13_gecko_rubi

New member
Problem is that on long drives my auto start will not even kick in as it states the voltage is to low. This happens around 12.4 and when I go long streatches without coasting. I am fine with it as it is designed that way. But at that time it had me concerned as I am used to 14.1 while motor is running.
What you are used to is old vehicles that run a constantly excited alternator. Voltage doesn't matter. It's calculating battery state of charge. If it thinks battery is charged it will only run alt hard enough to supply necessary current to keep vehicle running. Not extra to run vehicle and charge battery as it's already charged. All new vehicles do this. It's for fuel economy but it also greatly extends battery and alternator life as well. We were doing this in other industries I worked in decades ago. The auto folks have only started doing it recently.

Did u add extra accessories to the vehicle? If so where did you tie them in? You didn't put anything to the negative terminal on the battery post side of the current sensors did you?

Sent via....
 

ubbb69

Member
What you are used to is old vehicles that run a constantly excited alternator. Voltage doesn't matter. It's calculating battery state of charge. If it thinks battery is charged it will only run alt hard enough to supply necessary current to keep vehicle running. Not extra to run vehicle and charge battery as it's already charged.

Did u add extra accessories to the vehicle? If so where did you tie them in? You didn't put anything to the negative terminal on the battery post side of the current sensors did you?

Sent via....

Pretty sure you did not even read my posts. Even the tech that rode with me was surprised at the charge the software called for at different times. All was in spec and I am fine with it. And yeah I guess if 2016 is old tech at this time that is what i am used to. It still makes no since that the battery will be allowed to go to low for the main system in place for mileage.
 

13_gecko_rubi

New member
Pretty sure you did not even read my posts. Even the tech that rode with me was surprised at the charge the software called for at different times. All was in spec and I am fine with it. And yeah I guess if 2016 is old tech at this time that is what i am used to. It still makes no since that the battery will be allowed to go to low for the main system in place for mileage.
I did read your posts. What was your 2016? 2018 JKs even use old tech charging along with many other vehicles.

You are right it should not drain over mileage. It should maintain the battery. Did you add accessories to the jeep or is it still stock?

Sent via....
 

notnalc68

That dude from Mississippi
Pretty sure you did not even read my posts. Even the tech that rode with me was surprised at the charge the software called for at different times. All was in spec and I am fine with it. And yeah I guess if 2016 is old tech at this time that is what i am used to. It still makes no since that the battery will be allowed to go to low for the main system in place for mileage.

Pretty sure he’s an engineer for Jeep, so he knows what’s going on. The tech from the dealership? Who knows if he knows what he’s talking about?


Sent from my iPhone using JL Wrangler Jeep Forum mobile app
 

Top