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3.6L ESS IBS Information

Yellow Cake Kid

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The only comments I can add that may be helpful are a reminder that current measurements made at the battery are observations of voltage drop across a shunt resistor. The measurement of current is used as a proxy estimation to evaluate the capacity status of the battery by making conclusions based upon expectations that the battery will present some level of resistance at some level of capacity.

With regards to the first comment, measuring voltage drop in a parallel array where the voltage in the system is constantly trending towards entropy may lead to abstractions that do not indicate the actual capacity of the battery. The current measurement will include both the effect of the primary function of the battery as well as the settling effect of the parallel array.

With regards to the second comment, as vehicle operators we tend to think in terms of cranking amps and the ability to power accessories, but an evaluation of a battery's effectiveness regards the capacity of the battery to repeatedly perform the function required. A current measurement represents an instantaneous state, while we are more often concerned with long term performance. As you suggested the IBS and BCM are capable of considering more than a single measurement. I think that seems to be a good thing.



These discussions have created a question in my mind; What is the expected benefit of the Intelligent Battery Sensor?

Is it primarily implemented to enable the charging system to be effective while the vehicle manages for maximum efficiency when harvesting the kinetic energy from the vehicle's motor, or is it primarily intended to maximize the health of the battery?

Does the system address one concern at the expense of the other or is the advent of this technology a panacea that optimizes the achievment of both goals?



Thank you for the discussion.
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Jebiruph

Jebiruph

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These discussions have created a question in my mind; What is the expected benefit of the Intelligent Battery Sensor?

Is it primarily implemented to enable the charging system to be effective while the vehicle manages for maximum efficiency when harvesting the kinetic energy from the vehicle's motor, or is it primarily intended to maximize the health of the battery?

Does the system address one concern at the expense of the other or is the advent of this technology a panacea that optimizes the achievment of both goals?



Thank you for the discussion.
As far as I know, the purpose of the IBS is to allow for the implementation of the Auto Stop Start system. It determines if the main battery will be able to power a restart from an auto stop and provides information that influences alternator output.
 

Yellow Cake Kid

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Thank you for explaining your perspective.

Here is an interesting article that elaborates on IBS implementation in vehicles:

https://bimmerscan.com/bmw-intelligent-battery-sensor-ibs/

  • State of Charge (SoC) is a calculated condition showing the current charge of the battery. SoC is used during key ”OFF” periods to insure the battery maintains a sufficient charge to start the engine at least one more time.
  • State of Health (SoH) tracks the history of the battery. Charge/dis-charge cycles and times are monitored. SoH helps the DME determine the proper charging rates and anticipated battery life. Internal resistance of the battery is calculated by the IBS from the current and voltage dip during engine start. The values are forwarded to the DME to calculate the SoH of the battery.

Note that the "State of Charge" description seems to pertain to the perspective you have been considering, while I have been focused on the ideas that concern the "State of Health".

It has been useful to see a perspective that differs from what I was familiar with.

Thank you!
 

Birdman

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I had this same issue stop start not working battery charging. About a year ago they replaced both batteries and it was fixed then last week it started again. Took it to the dealer both batteries were at 62% they charged batteries both good and deemed the issue was the IBS they have now replaced that so we will see. Can a faulty IBS cause this issue as well or is my dealer just guessing?
 
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Jebiruph

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I had this same issue stop start not working battery charging. About a year ago they replaced both batteries and it was fixed then last week it started again. Took it to the dealer both batteries were at 62% they charged batteries both good and deemed the issue was the IBS they have now replaced that so we will see. Can a faulty IBS cause this issue as well or is my dealer just guessing?
They are guessing, but it's a good guess. What's your running voltage? Battery status information from the IBS is used to increase alternator output as needed to keep the battery charged. If your alternator output is high enough to charge the batteries, I don't think the IBS is the problem, but I'm guessing also.
 

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Birdman

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They are guessing, but it's a good guess. What's your running voltage? Battery status information from the IBS is used to increase alternator output as needed to keep the battery charged. If your alternator output is high enough to charge the batteries, I don't think the IBS is the problem, but I'm guessing also.
The voltage was always staying around 14 before the fix even in park and idle after the fix and battery charge it’s now driving at 14 but goes down to 12.5 at idle behaving more like when the ESS was working before.
 
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Jebiruph

Jebiruph

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If your voltage is going up and down according to engine RPM, my guess is a bad alternator. Due to my limited driving even before working from home, my voltage always stayed in the mid 14s driving and idling.

I would at least have the dealer verify the alternator output next time they look at it.
 

WranglerMan

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If your voltage is going up and down according to engine RPM, my guess is a bad alternator. Due to my limited driving even before working from home, my voltage always stayed in the mid 14s driving and idling.

I would at least have the dealer verify the alternator output next time they look at it.
Jerry,

My 2018 JL had the voltage float like this when I first got it and then it stayed above 14 all the time and when they checked my batteries they found the main had failed ( shorted cell ) so replaced under warranty and they also checked the alternator and it was good along with the IBS and ESS battery.

I was advised at that time and told the voltage going up and down was normal as the JL uses a “smart“ alternator that only sends voltage to the batteries as needed and this is suppose to help fuel economy by not being under a load all the time.

After my main was replaced my EVIC display went back to floating up and down and now even with my new dual genesis system it floats up and down and I had a local shop recently check the alternator and they advised it’s putting out 14.3-14.5 at full load but also said it won’t do that all the time ( not sure how they test it )

Normally when I get in my JL after it’s been parked for 10-12 hours the EVIC displays 13.7-14.2 but after approx driving 30-45 mins on the highway it drops to the low 13’s and if I continue to drive it has even dropped to 12.8-12.9.

Usually after it comes off my NOCO 10 or Odyssey 20 ( reconditioning ) my voltage displayed running is 12.8 and stays that way for a day or so but then I have two big full size batteries and after that it’s normally in the 13.8-14.2 starting but as I drive it slowly drops and as I slow to brake or just slow down the EVIC voltage ramps up to over 14 then once stopped it drops off.

This was done on the way home yesterday



This is how smart alternator operation was explained to me

https://www.redarc.com.au/alternator-vs-fixed-alternator

Jerry you sir have so much more knowledge on the whole ESS operation than me but this from my understanding is how the charging side is supposed to work and my batteries are brand new and the IBS along with the alternator I was told was good, I wish I knew how to check the operation of my smart alternator but don’t, I do know and have verified that if my JL sits for 3-4 days not on a charger when I start it the EVIC normally displays 14+ volts and the main crank battery matches that and with the engine off the main after resting several days is around 12.55 due to the draw from the Cole Hersee solenoid on my dual system but after driving that voltage output from the alternator slowly drops as my main battery volts go up and like I said I was told this was very normal but some seem to see this and others like you see a constant 14+ all the time so who knows really.

I continue to read, enjoy and learn from all you posts and look forward to seeing more from you, we all learn from this a lot and I doubt I will ever fully understand FCA’s design on this system over the older charging system I am so used to seeing on other vehicles I have owned .
 

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@WranglerMan Hi Will, the voltage on my 2020 JL has always floated up and down after being driven for some time. It's not a daily driver and I haven't watched it closely enough to notice when the float starts but I do know that the voltage stays in the 14 volt range on a 20 minute drive. But, it will be floating after a several hour drive. It's easy to watch on a curvy mountain road where you're constantly either on the brakes or on the gas. The voltage varies directly opposite of the alternators of a few years back. When accelerating the voltage drops to around 13 volts and when braking it climbs up to ~14 volts. It seems like it operates very similar to your set up.

Later,
Johnny
 
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Jebiruph

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Jerry,

My 2018 JL had the voltage float like this when I first got it and then it stayed above 14 all the time and when they checked my batteries they found the main had failed ( shorted cell ) so replaced under warranty and they also checked the alternator and it was good along with the IBS and ESS battery.

I was advised at that time and told the voltage going up and down was normal as the JL uses a “smart“ alternator that only sends voltage to the batteries as needed and this is suppose to help fuel economy by not being under a load all the time.

After my main was replaced my EVIC display went back to floating up and down and now even with my new dual genesis system it floats up and down and I had a local shop recently check the alternator and they advised it’s putting out 14.3-14.5 at full load but also said it won’t do that all the time ( not sure how they test it )

Normally when I get in my JL after it’s been parked for 10-12 hours the EVIC displays 13.7-14.2 but after approx driving 30-45 mins on the highway it drops to the low 13’s and if I continue to drive it has even dropped to 12.8-12.9.

Usually after it comes off my NOCO 10 or Odyssey 20 ( reconditioning ) my voltage displayed running is 12.8 and stays that way for a day or so but then I have two big full size batteries and after that it’s normally in the 13.8-14.2 starting but as I drive it slowly drops and as I slow to brake or just slow down the EVIC voltage ramps up to over 14 then once stopped it drops off.

This was done on the way home yesterday



This is how smart alternator operation was explained to me

https://www.redarc.com.au/alternator-vs-fixed-alternator

Jerry you sir have so much more knowledge on the whole ESS operation than me but this from my understanding is how the charging side is supposed to work and my batteries are brand new and the IBS along with the alternator I was told was good, I wish I knew how to check the operation of my smart alternator but don’t, I do know and have verified that if my JL sits for 3-4 days not on a charger when I start it the EVIC normally displays 14+ volts and the main crank battery matches that and with the engine off the main after resting several days is around 12.55 due to the draw from the Cole Hersee solenoid on my dual system but after driving that voltage output from the alternator slowly drops as my main battery volts go up and like I said I was told this was very normal but some seem to see this and others like you see a constant 14+ all the time so who knows really.

I continue to read, enjoy and learn from all you posts and look forward to seeing more from you, we all learn from this a lot and I doubt I will ever fully understand FCA’s design on this system over the older charging system I am so used to seeing on other vehicles I have owned .
Thanks for the comments, I'm still learning about this stuff too and rely on everyone's posts to help analyze how things work.

My experience has been that my voltage never varies based on engine rpm. Specifically, if my driving voltage is 14.5v, my idle voltage is 14.5v. So if @Birdman 's voltage fluctuates between a driving voltage of 14v and an idle voltage of 12.5v, it looks to me like his alternator output is low.

This is different than the voltage dropping over time on a long trip as the charge builds in the battery. Having a driving/idle voltage of 14.5v at the start of the trip and a driving/idle voltage of 13.1v at the end of the trip would be the smart alternator detecting that less power was needed as the battery charged.
 

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Jebiruph

Jebiruph

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Here's a diagram of the JL alternator. It's not the alternator that's smart, it's the PCM that monitors and adjusts the alternator output. As various systems increase the load on the alternator, the PCM detects the load and increases alternator output by adjusting the field.

Jeep Wrangler JL 3.6L ESS IBS Information alternator 3.PNG


The PCM can increase alternator output if the IBS reports a low charge in the main battery to facilitate faster charging. This is what I think accounts for the high voltage on infrequently driven JLs like mine. And it also seems to increase alternator output during deceleration.
 

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Jerry,

I guess I needed to clarify and glad you took time to explain, I guess I should have been more clear on my voltage floating but what you detailed is my exact scenario, My starting idle voltage is the same as my running voltage and only floats during braking and deceleration but as you said the long one drives the lower that voltage will be due to the batteries getting charged.
 

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Hi all,

Really great thread. So many dynamic variables to grapple with but everyone here is making this over-the-top complicated contraption way more understandable. Especially to Jerry, really appreciate all your knowledge and willingness to share it with the rest of us. Kudos and thanks to all.

I'd like to provide another data point for your consideration.

I too have been struggling with constant high alternator output (typically >14.5v) regardless of whether at idle or not. It basically seemed like I had a bad battery. Several trips to the dealer always resulted in no trouble found (NTF). Both batteries load tested OK.

I have a 2019 Sport S 3.6L Auto (20K miles) completely stock ESS circuit. Very tempted to do Jerry's bypass but have held off because I'm the oddball who actually doesn't mind the Auto Stop/Start functionality. Truthfully, I enjoy it in most circumstances, but I digress.

My ESS routinely would be disabled due to "Battery Protection Mode". The only way it seemed I could keep the ESS working was to put a battery tender on my rig every other day or so. The tender always went into float mode quickly, within an hour or two. So this convinced me the batteries (in parallel) where fine.

Finally I got fed up, went and asked to see the Service Manager at the dealership. After a long discussion (based on all the great input from this thread) and to his credit, he agreed to take a small road trip with me. He also knew I had been in several times already, all resulting with NTF.

Sure enough, after the fourth or fifth red light (ESS event), the ESS stopped working with it's usual "Battery Protection Mode" complaint. The EVIC was consistently at or above 14.5v during the entire drive.

I was finally able to convince these people that a) my batteries are not adequately being charged or b) the IBS monitoring system isn't working as intended.

He 'reluctantly' had a tech replace the IBS with both of them saying that they never seen one go bad before.

Immediately after however, the alternator output dropped into the mid 13v range and I have yet to see ESS disabled due to any battery protection issue.

So I have a data point that strongly enforces your ideas of IBS functionality being key to running with higher than expected alternator output voltages.

On even short (<10 mile) trips, I now routinely see my EVIC display indicate high 12v readings.

Hope this helps enlighten some of your IBS discussion points.

Jay
 

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Good thread, I have had the ESS not ready due to battery charging for quite some time now. I disabled the AUX, and have no issues starting, so I think there could be an issue with the IBS as my voltage is always ~14.4 but I have to admit, I don't like ESS anyway and this saves me from hitting the button every time. I have been meaning to hook my charger up and get the battery to 100% and see what happens.

An interesting note, when the battery not charged enough issue started happening, I swear ESS would work on warmer days but not on cooler days. Over 80 degrees the ESS would engage and surprise me, but under 80 it would never come on.
 

jeepoch

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@cbrenthus,

Maybe you already know this, but batteries are way more efficient at higher temperatures. Chemical interactions at the molecular level naturally have higher kinetic energies at higher ambient temperature. This translates into higher voltage as temperature increases. Also lower voltage as temperature decreases.

If your battery has a low charge already, colder temperatures will naturally make things worse.

Jay
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