ESS Dual Battery Management

[Gee-pah]

I'd think that anyone running Jerry's N1 <-> N2 fused jumper hack, like you had prior @WranglerMan Will is apt to not be a great ESS fan--or at least a great ESS/Aux battery fan.

But that said, for all its ingenuity I'd also be apt to expressly disengage ESS with it installed, either by non-latching factory button push at cold crank or 3rd party gear.

I say this because it seems that with this hack installed, tests of the ESS battery prior to or during an ESS event might be a composite reading of the voltages of both batteries. This could lead to ESS events that might not occur, or remain in effect as long if ESS is activated at traffic stops, were the ESS batteries isolated as is the case from the factory.

This is NOT a stab at the hack. It's simply to say that at times workarounds sometimes have--as they say for medicines--contraindications--or situations where the benefits of its use can be outweighed by other factors. We don't want to drain the cranking battery in ESS events that normally wouldn't occur, or run as long, were the jumper not installed and the ESS battery managing *most of the power draw of an ESS event, presuming the main battery for engine cranking after the event ends.

*(I think at one point Jerry said that some operations do tax the main battery during ESS, like power steering.....as much as ESS won't engage if the steering wheel is turned.)

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[Jebiruph]

Thanks for your research, work and publication of this Jerry, along with your initial N1 <-> N2 fused jumper hack from a while back that could allow, say, a 2018 3.6L JL[U] to crank even if its ESS/Aux battery failed to meet voltage thresholds for the vehicle to attempt the crank (which is otherwise energized by both batteries).

In your more recent diagram of this thread you defined three different states of operation based upon the a) presence/absence of the fused jumper between terminals N1 and N2 of the high current fuses in the Power Distribution Center (PDC) and the b) on or off state of the connect/disconnect switch that forms part of the hardware of this thread. You named these three states as 1) Normal Operation, 2) Separated Batteries and 3) Aux Bypassed, which I'll use below for clarity.

Three questions:

Q1) Is it correct to say that your "Separated Batteries" state is not one that model year 2018 3.6L JL[U]'s without the flash (discussed on prior threads on the forum) to allow them, like model year 2019 and beyond 3.6L JL[U]'s to cold crank off of both batteries, or just the main battery (if the ESS/Aux battery fails its pre cold-crank testing) can use? If no, why?

Q2) Is it correct to say that your "Aux Bypassed" state would never engage the ESS system, (independent of the state of the factory non-latching bypass switch of 3rd party gear to disable ESS) because the IBS would not detect a voltage from the ESS/Aux battery? If no, why?

Q3) As an offshoot of Q2) why would, in your "Separated Batteries" state the 3.6L JL[U]'s not know, as you've stated, that the ESS battery was disconnected? Perhaps to rephrase the question, isn't such knowledge of the state of the ESS battery derived from the IBS--to which the ESS/Aux battery would not be connected to in your "Separated Batteries" state?

Please appreciate that none of these questions are critiques--just me trying to understand.

Thanks.

1. This is the same thing as disconnecting the aux battery negative cable from the main battery negative terminal as is done when charging the batteries separately.

2. It's the same aux bypass as always, running on 1 battery and after 6 ESS events, ESS is disabled.

3. As far as I can tell, there is no mechanism that allows the IBS to monitor more than 1 battery and in the JL it monitors the main battery.

There aren't any new concepts involved with this kit. There is a battery switch on the aux battery negative cable so the cable doesn't have to be removed and reinstalled. There is a fused bypass jumper from N1 to the main battery positive (same as N2, but more convenient in the case). And there volt meters to monitor the charge of each battery.

 

[WranglerMan]

@Jebiruph could one say disconnect the ESS positive from the ESS battery and run it to the main battery positive and then disconnect the ESS negative from the main negative and this would effectively let the ESS system see 12 volts for starting without issue and if this is the case the only caveat would be don‘t let the ESS system kick in to pull power from the main battery since it’s the only one your using.

If the above works one could effectively remove the ESS battery then disable ESS using a Tazer, Smart Stop/Start or similar tuner and possibly put in a larger main battery to make up for the parasitic draw that these JL’s use but now sure if this is even possible, I was thinking someone quite awhile back did this but maybe they were just thinking of doing it

 

[Jebiruph]

@Jebiruph could one say disconnect the ESS positive from the ESS battery and run it to the main battery positive and then disconnect the ESS negative from the main negative and this would effectively let the ESS system see 12 volts for starting without issue and if this is the case the only caveat would be don‘t let the ESS system kick in to pull power from the main battery since it’s the only one your using.

If the above works one could effectively remove the ESS battery then disable ESS using a Tazer, Smart Stop/Start or similar tuner and possibly put in a larger main battery to make up for the parasitic draw that these JL’s use but now sure if this is even possible, I was thinking someone quite awhile back did this but maybe they were just thinking of doing it

What you are describing is exactly what Genesis does, move the ESS positive cables to the main battery and disconnect the ESS negative.

This is also what's accomplished with the fused bypass jumper. The N1 terminal connects directly to the ESS positive. The N2 terminal connects directly to the main battery positive. So connecting N1 to N2 is the same as connecting the ESS battery positive to the main battery positive.

 

[MacJack]

Like so many have said, Jerry has helped us with his jumper for AUX battery. Thank God never needed it and was able to jump start my Jeeping buddy dead battery... I'm following this post as you guys are smarter them me and waiting to see what the final solution will be as a 2018 JLR battery system...

Keep up the research.

 

[Gee-pah]

@Jebiruph Jerry: I must not have my thinking cap on today.

Let me get the essense of my question up front. Is the Aux Bypass wiring configuration you show here https://www.jlwranglerforums.com/forum/threads/ess-dual-battery-management.60034/post-1291331 suppose to reflect your N1<-N2 jumpering hack of 2018. Is so, shouldn't the grounds between the 2 batteries be connected?


Restated:

In either the Separated Battery or Aux Bypass wiring configurations does the alternator energize the ESS/Aux battery? I think it does in the Aux Bypass where the fused jumper is the only thing the differs from factory wiring (but wouldn't the grounds between the two batteries have to be intact??? unlike what I see here https://www.jlwranglerforums.com/forum/threads/ess-dual-battery-management.60034/post-1291331 )


You mentioned the recommendation to periodically monitor the ESS/Aux battery voltage in what I presume is one or both of the wiring configurations other than the Normal Operation you describe above where an N1<->N2 fused jumper is lacking AND the wire from the ground of the ESS/Aux battery ties in uninterrupted to the ground of the main battery.

So I might hazard a guess that the alternator only charges the main battery in the Separated Battery wiring configuration and that every so often one must charge the ESS/Aux battery via external source as you did above at the correct ground contact point with the switch of this thread breaking the ground connection between the batteries, or revert to "Normal Operation" for a while where the alternator charges both batteries--either because the ESS/Aux battery has been expressly taxed by an owner for power, or natural processes where the ESS/Aux battery loses power over time have caused it to lose power in ways addressed by a trickle charger.

Thank you.

P.S. Are any of the configurations here https://www.jlwranglerforums.com/forum/threads/ess-dual-battery-management.60034/post-1291331 that are suppose to be just the fused jumper connected between N1 <-> N2 with the ground wire between the ESS/Aux battery and the main battery intact (i.e. your 2018 post on this)? If not what are we calling your hack from 2018--just "jumpering the two batteries?" (I just need a term so I can speak your language.) I think this is the source of my confusion.

Again, I seek to in no way critique--just have it make sense to me.

(So confused.)

 

[WranglerMan]

What you are describing is exactly what Genesis does, move the ESS positive cables to the main battery and disconnect the ESS negative.

This is also what's accomplished with the fused bypass jumper. The N1 terminal connects directly to the ESS positive. The N2 terminal connects directly to the main battery positive. So connecting N1 to N2 is the same as connecting the ESS battery positive to the main battery positive.

Jerry,

So the big benefit(s) of the Genesis System is:

1) Have two full size batteries that combined give a huge amount of amp hours for usage.

2) Has a automatic industry standard smart isolator and solenoid that work together to automatically monitor and isolate the batteries from each other to protect the crank battery once it falls below 12.6-12.8

3) Gives you the ability to push a “Boost” button under the hood or a button in the cabin if you have a the G screen that will give you a jump start from the aux battery if your crank battery has been drained to far down providing you have not sucked your full size aux battery down running aux accessories like aux lights, winch, air compressor etc..

4) The ability to change batteries without having to pull a fender flare or take out the PDC and risk breaking something.

As we all know the Genesis System is not inexpensive but honestly what on a Jeep is ?

I personally compare it to everything else I have put into my JL like my lift, 35” tires, beefed up steering stabilizer, winch, aux lighting, compressor etc..... I have pondered doing it for quite sometime and even though I have had zero trouble and I mean zero trouble outside of the normal recalls that we all go thru and one main battery replaced 7 months into ownership I just liked the design and opted for a better design over what FCA chose to put into the JL and to be honest had they put that ESS battery in a more accessible area like in the engine bay or even in the back somewhere I would have most likely never invested the coin into a new setup but I will enjoy not worrying anymore for a long time about batteries as I hope it gives me many years of trouble free service.

I have noticed the my smart charging system seems to work so much better like today after being parked for 12-13 hrs I got in my Jeep and the EVIC voltage display showed 14.1 but within a 30 min drive home it was down to 12.9-13.0 and did that crazy voltage going up and down during acceleration and braking and this is by design of the JL and my original setup before all of this it stayed above 14.0 volts 99% of the time and even after driving for an hour or two never for down to 13.0 volts so I’m guessing the new battery or should I say batteries have been a huge impact on this as the batteries are connected as one 99.99% of the time thru the smart isolator.

 

[Jebiruph]

@Jebiruph Jerry: I must not have my thinking cap on today.

Let me get the essense of my question up front. Is the Aux Bypass wiring configuration you show here https://www.jlwranglerforums.com/forum/threads/ess-dual-battery-management.60034/post-1291331 suppose to reflect your N1<-N2 jumpering hack of 2018. Is so, shouldn't the grounds between the 2 batteries be connected?


Restated:

In either the Separated Battery or Aux Bypass wiring configurations does the alternator energize the ESS/Aux battery? I think it does in the Aux Bypass where the fused jumper is the only thing the differs from factory wiring (but wouldn't the grounds between the two batteries have to be intact??? unlike what I see here https://www.jlwranglerforums.com/forum/threads/ess-dual-battery-management.60034/post-1291331 )


You mentioned the recommendation to periodically monitor the ESS/Aux battery voltage in what I presume is one or both of the wiring configurations other than the Normal Operation you describe above where an N1<->N2 fused jumper is lacking AND the wire from the ground of the ESS/Aux battery ties in uninterrupted to the ground of the main battery.

So I might hazard a guess that the alternator only charges the main battery in the Separated Battery wiring configuration and that every so often one must charge the ESS/Aux battery via external source as you did above at the correct ground contact point with the switch of this thread breaking the ground connection between the batteries, or revert to "Normal Operation" for a while where the alternator charges both batteries--either because the ESS/Aux battery has been expressly taxed by an owner for power, or natural processes where the ESS/Aux battery loses power over time have caused it to lose power in ways addressed by a trickle charger.

Thank you.

P.S. Are any of the configurations here https://www.jlwranglerforums.com/forum/threads/ess-dual-battery-management.60034/post-1291331 that are suppose to be just the fused jumper connected between N1 <-> N2 with the ground wire between the ESS/Aux battery and the main battery intact (i.e. your 2018 post on this)? If not what are we calling your hack from 2018--just "jumpering the two batteries?" (I just need a term so I can speak your language.) I think this is the source of my confusion.

Again, I seek to in no way critique--just have it make sense to me.

(So confused.)

If you disconnect the aux battery ground cable, the aux battery is isolated and cannot be charged by, or discharge into the system. People do this to charge the batteries separately or, along with the bypass jumper, to run a single battery system. All the battery switch does is disconnect and reconnect the aux battery negative cable for the same separate charging or single battery system.

If you are running with the batteries separated and you see the aux battery charge is low, you can reconnect it until it's charge by the alternator, then disconnect it again.

The bypass jumper still does the same thing, allows the operation of a single battery system by providing main battery power to N1 that normally gets powered from the aux battery.

 

[WranglerMan]

@Jebiruph i have a question in regard to the ESS negative, if it’s disconnected off the main or in my case off both ends since my ESS battery is gone how does the JL determine that starting voltage is available with the ESS negative not connected, I’m guessing as long as it sees 12+ volts on the positive side that’s all that is needed so if someone is running a jumper between N1 and N2 or in my case I have my ESS positive connected to the main crank battery it’s seeing the needed 12 volts

 

[Jebiruph]

@Jebiruph i have a question in regard to the ESS negative, if it’s disconnected off the main or in my case off both ends since my ESS battery is gone how does the JL determine that starting voltage is available with the ESS negative not connected, I’m guessing as long as it sees 12+ volts on the positive side that’s all that is needed so if someone is running a jumper between N1 and N2 or in my case I have my ESS positive connected to the main crank battery it’s seeing the needed 12 volts

The system uses the status of the battery as reported by the IBS to determine if there is enough power to restart before it auto stops. The IBS reports on the battery it is attached to, normally the main battery. The thing I don't like about the Genesis installation is that they connect the IBS to their second battery, not the main battery.

The concept of the IBS seems to confuse people. It's really no different from the battery monitoring in your phone or laptop. Those batteries are monitored for discharging and charging and the estimate of the remaining charge is displayed. They also warn and can act on a low charge level.

 

[Yellow Cake Kid]

The way I look at it is that there is undue preoccupation with the "ESS factor". The Engine Stop Start function is straightforward; the engine stops and the engine starts.

The complication is introduced by the insistence for drawing power while the engine is off under the premise that the practice can be exercised without impacting the effectiveness of the starter battery.

The strategies differ, as evidenced by the system offered by FCA as OEM for the Jeep, and the system imagined by Genesis.

I have not studied the Genesis system. I have been concerned with understanding the OEM Jeep system because that is what I am operating in my vehicle.

As has been discovered the Jeep's Power Control Relay is a cornerstone to the complications that Jeep introduced to vehicle operation.

The urge to bypass the Jeep's Power Control Relay seems like a natural response to the inconvenience the PCR offers.

Any system that ties two dissimilar batteries, or two batteries tied together that are tasked to different use is doomed to present troublesome experiences.

I am under the impression that the Genesis system attempts to address many or most of the issues encountered when running two batteries for different tasks, but it seems to do so with extremely complicated and convoluted circuitry.

Adding the ability to disconnect the Jeep's two OEM battery scheme seems like a good idea. Utilizing the additional switching to reconnect the parallel connection may seem to offer a quick boost for the starting system, and it may seem like a quick and easy solution, but it is not the most efficient use of the potential energy you are transporting.

The result of disconnecting the auxiliary battery and temporarily reconnecting it as a booster is that some of the downsides of running two dissimilar batteries are retained. The behavioral relationship between the two batteries is reversed. The aux battery will now sacrifice itself to charge the primary battery, where as in the unmodified system the primary battery tends to sacrifice itself to support the auxiliary battery. Regardless, of the configuration, the parallel circuit of dissimilar batteries will result in a system where battery life cycles are being squandered to charge batteries.

FWIW, a simple array of matched batteries placed in a full time parallel circuit offers great benefits with regard to increased capacity. This obvious option seems to be disregarded because the underlying premise is that vehicle owners want to be able to run one power system down while retaining capability of another system.

For my part, when my auxiliary battery ages, I will remove it and send it to the core yard. I do not intend to replace it. It is unnecessary and I do not see any benefit to using it.

A single battery system has served me well for several million miles of driving. Speaking for myself, a single battery has proven adequate, so I think that the practice of relying on one battery will continue to serve my needs.

If and when I voluntarily elect to add a second battery, I will pursue a system where the auxiliary battery is a completely independent battery where the system functions with an either one or the other, but not both, circuit layout. I will probably rely on a small wrench and bit of manual intention.

As I mentioned previously, I think the Genesis system seems to offer some features that address my concerns, but it seems to rely on a tangle of components to do something that has the potential to be very simple.

I do not want to offer discouragement for the concept introduced in the original post, but do feel that modifications that do not eliminate the parallel mismatch of batteries, or battery use, are only a stepping stone towards an appealing solution.

 

[Yellow Cake Kid]

The concept of the IBS...

I submit that the primary function of an IBS is to optimize the charge cycle pattern for the benefit of the owner of the battery. The IBS enables the application of best practice for charging the battery. It is a fantastic feature. It may have become ubiquitous and familiar, but the benefit for the charging system is remarkable.

The ability to share the information with other systems for purposes such as display of status, or determinations of eligibility for use in a switched network, has been exploited to pursue these secondary functions.

 

[WranglerMan]

The system uses the status of the battery as reported by the IBS to determine if there is enough power to restart before it auto stops. The IBS reports on the battery it is attached to, normally the main battery. The thing I don't like about the Genesis installation is that they connect the IBS to their second battery, not the main battery.

The concept of the IBS seems to confuse people. It's really no different from the battery monitoring in your phone or laptop. Those batteries are monitored for discharging and charging and the estimate of the remaining charge is displayed. They also warn and can act on a low charge level.

I have chatted with Shane and Mike at Genesis on several questions and from my understanding the reason the IBS is connected to the aux battery is that is not only the battery used to run say your winch and any other accessory its your backup battery and if say the IBS was connected to the main and you ran the main down the Jeep would not start unless you boosted it and when it’s in normal operation the batt are connected together so it’s basically one big 12 volt battery, so I believe it’s connected there as more reliable point as 99.99% of the time they are connected together thru the smart battery isolator so the IBS will always see 12+ volts but if it were connected to the main and you say left anything on in the Jeep it would pull the main battery down and once it got to 12.7 volts it would disconnect from the aux/backup and as the volts continued to drop the Jeep would not see the start voltage needed, you could still boost thru the aux to get you going though

I’m sure I’m missing something so maybe I need to ask them directly on why they did it the way they did to give a better answer

 

[WranglerMan]

The way I look at it is that there is undue preoccupation with the "ESS factor". The Engine Stop Start function is straightforward; the engine stops and the engine starts.

The complication is introduced by the insistence for drawing power while the engine is off under the premise that the practice can be exercised without impacting the effectiveness of the starter battery.

The strategies differ, as evidenced by the system offered by FCA as OEM for the Jeep, and the system imagined by Genesis.

I have not studied the Genesis system. I have been concerned with understanding the OEM Jeep system because that is what I am operating in my vehicle.

As has been discovered the Jeep's Power Control Relay is a cornerstone to the complications that Jeep introduced to vehicle operation.

The urge to bypass the Jeep's Power Control Relay seems like a natural response to the inconvenience the PCR offers.

Any system that ties two dissimilar batteries, or two batteries tied together that are tasked to different use is doomed to present troublesome experiences.

I am under the impression that the Genesis system attempts to address many or most of the issues encountered when running two batteries for different tasks, but it seems to do so with extremely complicated and convoluted circuitry.

Adding the ability to disconnect the Jeep's two OEM battery scheme seems like a good idea. Utilizing the additional switching to reconnect the parallel connection may seem to offer a quick boost for the starting system, and it may seem like a quick and easy solution, but it is not the most efficient use of the potential energy you are transporting.

The result of disconnecting the auxiliary battery and temporarily reconnecting it as a booster is that some of the downsides of running two dissimilar batteries are retained. The behavioral relationship between the two batteries is reversed. The aux battery will now sacrifice itself to charge the primary battery, where as in the unmodified system the primary battery tends to sacrifice itself to support the auxiliary battery. Regardless, of the configuration, the parallel circuit of dissimilar batteries will result in a system where battery life cycles are being squandered to charge batteries.

FWIW, a simple array of matched batteries placed in a full time parallel circuit offers great benefits with regard to increased capacity. This obvious option seems to be disregarded because the underlying premise is that vehicle owners want to be able to run one power system down while retaining capability of another system.

For my part, when my auxiliary battery ages, I will remove it and send it to the core yard. I do not intend to replace it. It is unnecessary and I do not see any benefit to using it.

A single battery system has served me well for several million miles of driving. Speaking for myself, a single battery has proven adequate, so I think that the practice of relying on one battery will continue to serve my needs.

If and when I voluntarily elect to add a second battery, I will pursue a system where the auxiliary battery is a completely independent battery where the system functions with an either one or the other, but not both, circuit layout. I will probably rely on a small wrench and bit of manual intention.

As I mentioned previously, I think the Genesis system seems to offer some features that address my concerns, but it seems to rely on a tangle of components to do something that has the potential to be very simple.

I do not want to offer discouragement for the concept introduced in the original post, but do feel that modifications that do not eliminate the parallel mismatch of batteries, or battery use, are only a stepping stone towards an appealing solution.

Im not as educated as a lot of techie guys but I personally don’t see the genesis system as complicated system as it basically uses a industry standard smart battery isolator with a solenoid that either connects or disconnects based on a preset voltage which is 12.7 +/-.1 so it can disconnect the main from 12.6-12.8 and once the main sees 13.2 for several minutes the isolator energizes the electromagnet in the solenoid and the batteries are once again connected and act as one and for the most part they are like this 99% of the time.

I’m sure at some point a failure will occur but if we wanted simple we would give up all the power grabbing goodies in these modern vehicles and go back to a simple system of one battery with manual windows and a am/fm radio but we all want our Bluetooth accessories along with phones, built in navigation, winches, lights, refrigerators etc....and expect them all to run without issues but that’s not going to happen so the best we can hope for is makers like FCA, Ford etc... do there part to design a better system and if they don‘t then we have to rely on makers like tazer, Flashcal, Genesis Off-road etc ...to come up with a better built mousetrap.....

Are all of these systems perfect.......NO THEY ARE NOT but we have to make the best case guess on what we personally need as owners and make the mod changes as we see fit and hope for the best

 

[Yellow Cake Kid]

It is an over simplification to regard the parallel interconnection of a fully charged primary battery and the partially charged secondary battery as acting as one, and that is the basis of my interest in this subject.

It seems as if Genesis has put a lot of thought into providing a solution, but it appears that the Genesis system charges the secondary battery by placing it back in the parallel array so it may be charged.

If that is so, the secondary becomes a parasite to the primary battery until the system reaches equilibrium.

A system could be devised that dedicated the charging to one or the other battery and not both at once.

That is the kind of dual battery management that appeals to me.

Perhaps the Genesis actually does this? As I mentioned, I have not studied its function. I have only read their 2018-2020 Jeep Wrangler JL Dual Battery Kit webpage, and at face value it appears to imply the parasitic circumstance I have described.

Nevertheless, as you explain, the end user experience provided by Genesis and Jerry's solutions will meet many users' needs and expectations. That is what matters. I agree.

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