Auto Stop/Start Stopped working.

[BajaTJ]

Yes. It's nothing to do with amperage, it's the voltage control they have programmed into these.
It could be a 10,000 amp alternator and if it doesn't run at the voltage required to charge a battery, it won't charge the battery.

Ok, but the 240a alternator has the same voltage output as the standard one?

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[Jeep-A-Kneez]

Finally got the yuck-yucks at the service department to swap out the original main battery, the start/stop system hasn't worked for months. Though I despise the system, the vehicle is new and should work properly. So far so good, time will tell.

 

[Wasatch1]

Good luck my friend. They changed my batteries months ago, then failed again, did 3hr recharge. 2nd time, said I'm not driving enough , now back on this post, round 3. Hopefully your experience is positive.

 

[Jeepfreak22]

Just had my aux battery changed for the 3rd time in three years. Was out of warranty 42,000miles, but the 2nd battery was only 11 months old. Had to replace the main battery at 36,560 miles at my expense but still 3 months before the 3yrs was up. Question, is this going to a constant problem? Has anyone just removed this thing permanently? Maybe the after market can come up with something, just really fed up with this crappy unreliable system.

 

[sharpsicle]

Ok, but the 240a alternator has the same voltage output as the standard one?

Yes, otherwise you'd fry the electronics. Everything is built around a 12v system. Voltages on alternators don't change, just the max amperage output.

 

[BajaTJ]

Yes, otherwise you'd fry the electronics. Everything is built around a 12v system. Voltages on alternators don't change, just the max amperage output.

I should have asked, “voltage output range” . Thanks for the reply!

 

[ShadowsPapa]

Yes, otherwise you'd fry the electronics. Everything is built around a 12v system. Voltages on alternators don't change, just the max amperage output.

I've received several more requests for alternator restorations - if you were closer I'd hire you to help get a few done.


Anyway, like the man said - it's all "12 volt systems". You could have a 10,000 amp alternator (man, I'd hate to lift that thing) and it would still be regulated at "battery voltage.
But if regulation goes awry, they can kick out enough voltage to fry things. Even an old 35 amp alternator can pass 16 volts if full-fielded.

The amperage only means it can deal with more draw or load or electrical need without dropping the voltage below 12-ish.
When testing a 60 amp alternator, when I crank the carbon pile to load it, I watch the amperage climb but as it approaches the max it can put out, the voltage plummets.
With a 35 amp, it can only hit 30-ish amps before the voltage takes a dump.
If I cranked into a 120 amp, I could approach 100-110 amps before the voltage would drop below 12 and so on.
So the larger alternator only means it can handle a much larger load or draw (in amps) before petering out and dropping voltage.
Think of the portable or stand-by generators for your house - they all put the same voltage out, but the load they can handle varies before they can no longer maintain the voltage needed.

In these, or other vehicles, regardless of alternator size in amperage, they all have the same voltage output/range, and it's regulated by the field current provided by the PCM. (voltage regulation has been built into the PCM since the 90s in Jeeps)

Just had my aux battery changed for the 3rd time in three years. Was out of warranty 42,000miles, but the 2nd battery was only 11 months old. Had to replace the main battery at 36,560 miles at my expense but still 3 months before the 3yrs was up. Question, is this going to a constant problem? Has anyone just removed this thing permanently? Maybe the after market can come up with something, just really fed up with this crappy unreliable system.

It is not the ESS doing that. Even those who have it turned off using tazer aren't immune to the AGM battery life issue.
I did some digging, hit a few battery sites, including a couple sites that make and sell batteries, I was shocked to see words like "average life 3 years" - huh?
Yeah, that was a constant theme - typical live on batteries like these, especially in heat, is only about 3 years. Holy crap - I may as well go back to the old wet cell lead acid batteries where I can squeeze 6, 7 or even 12 years out of them. (just kidding as there are other advantages to AGM batteries - but the short life is killer)

Changing to a pure dual battery system of 2 batteries of equal size would be an option - those seem to do better.
Jeep also hasn't gotten the charging profile right in these IMO - although my 2022 is doing fantastic so far. The charging pattern is far better than my 2020 was - at least that I've observed.

I would ask - did the shop that did the replacing follow the book? Both batteries completely charged to 100% SOC, independently, the IBS reset, then put back together? You don't just quickly swap batteries and drive it out.

 

[BajaTJ]

I've received several more requests for alternator restorations - if you were closer I'd hire you to help get a few done.


Anyway, like the man said - it's all "12 volt systems". You could have a 10,000 amp alternator (man, I'd hate to lift that thing) and it would still be regulated at "battery voltage.
But if regulation goes awry, they can kick out enough voltage to fry things. Even an old 35 amp alternator can pass 16 volts if full-fielded.

The amperage only means it can deal with more draw or load or electrical need without dropping the voltage below 12-ish.
When testing a 60 amp alternator, when I crank the carbon pile to load it, I watch the amperage climb but as it approaches the max it can put out, the voltage plummets.
With a 35 amp, it can only hit 30-ish amps before the voltage takes a dump.
If I cranked into a 120 amp, I could approach 100-110 amps before the voltage would drop below 12 and so on.
So the larger alternator only means it can handle a much larger load or draw (in amps) before petering out and dropping voltage.
Think of the portable or stand-by generators for your house - they all put the same voltage out, but the load they can handle varies before they can no longer maintain the voltage needed.

In these, or other vehicles, regardless of alternator size in amperage, they all have the same voltage output/range, and it's regulated by the field current provided by the PCM. (voltage regulation has been built into the PCM since the 90s in Jeeps)

Copy! Thanks!

 

[Wasatch1]

Has anyone tried an Optima battery? I have one in my 96 911 that works great. Only trickle charged mid winter for low temps or snow. It's going on 6-7 years no jumps. Took my truck on another high load 6% freeway camping trip again. ESS working 1 week, but turned it off a few times due to 100 degrees temps.. Didn't dive it this weekend, used the 911, so just curious, if it will work Monday and if so, a few days or more? Just trying to track my personal truck ESS drama ?

 

[Jeepfreak22]

Yes the last two were both replaced following the required procedure

 

[SargeDiesel]

What does the dash screen say? It gives you the status of the system on one of the pages. There are a bunch of reasons that it won't engage that system, and they aren't necessarily it "being broken". It needs conditions to be just right to function.

Not necessarily..... mine works when it feels like it.... but when it doesn't, it only says "not ready"... I'm assuming it is because the aux battery is low.

t

 

[SargeDiesel]

So I took the truck to the dealer today for some troubleshooting on my perceived battery issue. To recap, my battery died twice sitting in the garage after not driving it for a week. I don't drive it much (6000 miles since April 2021). My concern was "something" was drawing down the battery....perhaps my Rockslide Engineering Stepsliders? I installed a battery tender and charged the battery full before going into the dealership today. Guess what, everything, including the auto start/stop, was working normally. Dealer tested the batteries and found them to be perfectly fine. They performed a draw test and determined there was a .1 amp draw on the system. They depowered the step sliders and the draw went to .002 amps. The max recommended draw is .05 amps according to Jeep. They then repowered the step sliders and reset the circuit breaker for the step sliders. Draw was then measured again at .002 amps. So, in conclusion, it seems the step sliders were not the culprit but rather my driving habits not adequately keeping the battery charged. I suppose this is good news in that there is nothing wrong with my truck. The battery tender should alleviate the battery from dying on me in the future.

On a side note, the mechanic said that it could be.....that when the battery died the first time from the infrequent driving, something went "haywire" with the step slider logic thus creating an abnormally high draw. It's his belief that pulling the circuit breaker for the step sliders somehow reset the logic of that system which corrected the .1 amp draw that he noted during testing. Since the draw then returned to .002 amps, things appear to return to normal.

Oh well. At least Jeep did not charge me for this servicing today and gave my truck a clean bill of health. From now on, I will plug her in to let the battery tender every now and again to keep everything topped off.

I know this is going back a bit, but your situation seems a lot like mine... always "not ready" how did you hook up your battery to charge ? I charged my batteries and still had the message, with the dual battery setup, the way you charge seems to matter. Thanks

 

[jebiruph]

Not necessarily..... mine works when it feels like it.... but when it doesn't, it only says "not ready"... I'm assuming it is because the aux battery is low.

t

Because there isn't a battery sensor monitoring the aux battery, there is no way for the system to know the state of charge of the aux battery until it actually fails. The aux battery is tested during every cold start and if it fails, ESS is disabled and the error light turned on.

 

[peterpilot379]

Sarge, it sounds like your your aux battery is faulty. That was the problem with mine even though the dealer claims it tested good. After they replaced my aux and main battery, I’ve been trouble free with the Stop/Start System.

Attached is a picture of my charger location and circleswhere attached to the battery. I haven’t had to us it since replacing both batters.

note to self, if this problem occurs again, I’m going todo that dual battery kit that everyone raves about on this forum.

 

[SargeDiesel]

Because there isn't a battery sensor monitoring the aux battery, there is no way for the system to know the state of charge of the aux battery until it actually fails. The aux battery is tested during every cold start and if it fails, ESS is disabled and the error light turned on.

Thank you for the info.......

So if tested & fails at start-up, I wouldn't get the "battery charging " error, because it would not send a charger due to failure ?

So from getting the "not ready " only, would this lead you to believe the AUX battery is bad, or just low from lack of driving ?

So the IBS, doesn't monitor both batteries ? If not, is the only reason the -neg cables are bound together ontop of the main battery for the parallel connection ?

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