Cheap ESS battery quick disconnect & applying TSB 18-092-19 for failed ESS battery

[Htfan]

Thought I would share a cheap/quick mod I've added for peace of mind. I've already had to replace (under warranty) one bad ESS battery that started to drain my main battery before it was replaced.

I know there are other more complicated/expensive options available which include voltage sensors and high Amp relays. This mod is $7 and 5 minutes. It allows the quick disconnect of the ESS battery ground without tools.

If the ESS battery becomes a problem again, just a quick turn of the knob and it's isolated. I also have a fused N1/N2 jumper if I don't want to see the P00FD error code (and "circle A" error on dash).

The other fused line you see across the main battery is not related and just my battery tender connection.

Note: I recently had my PCM updated on TSB 18-092-19 which resolves a number of issues including the way the JL handles a failed ESS battery. EDIT - Make sure that you have a fused jumper on N1 & N2 if you don't have the latest PCM update. Otherwise the jeep won't start with the ESS battery disconnected!

Hope this helps others!

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[DanW]

Thought I would share a cheap/quick mod I've added for peace of mind. I've already had to replace (under warranty) one bad ESS battery that started to drain my main battery before it was replaced.

I know there are other more complicated/expensive options available which include voltage sensors and high Amp relays. This mod is $7 and 5 minutes. It allows the quick disconnect of the ESS battery ground without tools.

If the ESS battery becomes a problem again, just a quick turn of the knob and it's isolated. I also have a fused N1/N2 jumper if I don't want to see the P00FD error code (and "circle A" error on dash).

The other fused line you see across the main battery is not related and just my battery tender connection.

Note: I recently had my PCM updated on TSB 18-092-19 which resolves a number of issues including the way the JL handles a failed ESS battery.

Hope this helps others!

THat is GREAT! Where can I get that part?

 

[Htfan]

THat is GREAT! Where can I get that part?

You can find them many places. Here's an Amazon link for one similar to what I installed.

https://www.amazon.com/Ampper-Batte...MF2FN9JQVHC&psc=1&refRID=1J9JV8E9WMF2FN9JQVHC

 

[Gee-pah]

Thought I would share a cheap/quick mod I've added for peace of mind. I've already had to replace (under warranty) one bad ESS battery that started to drain my main battery before it was replaced.

I know there are other more complicated/expensive options available which include voltage sensors and high Amp relays. This mod is $7 and 5 minutes. It allows the quick disconnect of the ESS battery ground without tools.

If the ESS battery becomes a problem again, just a quick turn of the knob and it's isolated. I also have a fused N1/N2 jumper if I don't want to see the P00FD error code (and "circle A" error on dash).

The other fused line you see across the main battery is not related and just my battery tender connection.

Note: I recently had my PCM updated on TSB 18-092-19 which resolves a number of issues including the way the JL handles a failed ESS battery.

Hey Jeff. Thanks for taking the time to write this up.

I do though think there needs to be an understanding of what is going on, and its implications by those that adopt this approach.

This is NOT to throw a monkey wrench into your ideas. Rather, it is to explain what's happening and the implications/contraindications of this design--at least as I best understand what I think you've done.

Correct me if I am wrong Jeff but it seems like on your main battery's negative/ground post you have added a device that allows the negative/ground wire from the ESS/Aux battery to be temporarily disengaged from the main battery's negative post--where it normally connects.

This is fine, but for some 3.6L owners it is mandatory that your fused jumper between the N1 and N2 terminals on the Power Distribution Center (PDC)--or N1 and the main battery positive post (same exact thing) be there as well or that 2018 won't crank. Again I think you appreciate this by your talk of the TSB 18-092-19 flash I discuss below, I just want to make that clear to the masses.

It's not that you said differently.

Here's the skinny. All 3.6L JLs test the ESS/Aux battery in isolation prior to cranking the engine. In 2018 3.6L JLs that haven't been flashed with the TSB 18-092-19 update you refer to, if the ESS/Aux battery doesn't pass this test the vehicle won't crank. It makes no difference whether the main battery is fully charged.

If you have a 2019 model year 3.6L JL or greater, or a 2018 with this flash, and your ESS/Aux battery lacks charge during this isolation test of its power I describe above, the vehicle will throw the diagnostic code you report, and upon an operator's subsequent attempts to crank the vehicle, switch over to the main battery to attempt to the crank.

Mind you, in any model year 3.6L JL, if the ESS/Aux battery passes this test, both batteries are connected in parallel by the vehcile to energize the crank. Baring Jeff's hack, all 3.6L JL model year vehicles keep the batteries in parallel at all times but for ESS events and the aforementioned instant at cold crank.

By Jeff placing a fused jumper on terminal N1 of the Power Distribution Center (PDC) that black box on top and in back of the engine bay near the passenger's seat, he has connected to the ESS/Aux battery. The other end of the fused jumper, attached to N2, or the main battery's positive terminal (it makes no difference) makes any vehicle test of the ESS/Aux battery a test that is of the composite voltage of both batteries.

That said, disconnect the ESS/Aux battery at the negative post of the main battery and Jeff has created a 3.6L JL where the ESS/Aux battery has been taken out of the loop, and is solely run on one main battery.

The tests of the ESS/Aux battery upon startup, because of Jeff's wiring change have fooled the 3.6L JL into thinking that it's testing the ESS/Aux battery when it's really testing the main battery.

Finally, when using this setup, it is advised to not allow ESS to engage.

Here's why:

In the factory setup, with your foot on the brake at a traffic light and all other ESS conditions met (i.e. you're not in a manual gear in an automatic, the steering wheel isn't turned, the engine is warmed up, etc.) the vehicle will test the ESS/Aux battery for an even higher threshold of voltage than needed to effect that cold crank. If this is met the vehicle will isolate the batteries, turn off the engine, and run appliances off of the ESS/Aux battery, monitoring it continually. If it's voltage dips too low, the ESS event is ended before the operator takes their foot off the brake, the batteries are reconnected, and the engine is cranked mostly with the power of the preserved main battery, so the alternator can charge both batteries.

Now let's look at what happens under Jeff's wiring--which is NOT a critique of his ideas, just why ESS is best not run with it enabled and an explanation of what's happening in this wiring scheme.

In Jeff's system, if all the criterion for engaging ESS are met, as usually the vehicle goes through the motions of checking the ESS/Aux battery's voltage both prior and during an ESS event, but given his wiring change the 3.6L JL is really testing only the main battery.

Assuming that main battery has power, the ESS event engages. If voltage dips too low, as usual, the vehicle switches the wiring to join both batteries and crank, only with Jeff's wiring the only battery is the main one--the very one depleted in the ESS event (NOT the separate ESS/Aux battery designed to bear this load to preserve the main battery for the crank) and engine cranking is threated.

With the jumper between N1 and N2 intact, but Jeff's changes at the main battery's negative post not installed (or engaged) what you've done is parallel connect both batteries 100% of the time. This too is a situation best contraindicated for running ESS as you will be taxing the main battery during ESS events in this setup too, only less because the ESS/Aux battery IS brought into the "electrical fold" of things.

I hope this educates. It is NOT my intention to be a smart ass. Jeff, you are a good guy; we've spoken privately before about the EZ Trunk you introduced to the forum.

Peace.

 

[Htfan]

Hi @Gee-pah

Appreciate your post!

Yes, to confirm if you choose to disconnect the ESS battery you MUST either have:

- fused jumper on N1 & N2 or
- the updated PCM programming I mentioned in the original post. (I believe starting in my2019 + this functionality came installed from the factory)

Otherwise the jeep won't start.

 

[WranglerAz]

Thanks for writing this up, lots of good learning info here.

I do not know if my 2018 has the PCM patch, is there e way on the vehicle to find out, or do i need to take it to a dealer?

For the N1 N2 jumper, what part do I need? Is this a pre made item I can purchase?

 

[Gee-pah]

Thanks for writing this up, lots of good learning info here.

I do not know if my 2018 has the PCM patch, is there e way on the vehicle to find out, or do i need to take it to a dealer?

For the N1 N2 jumper, what part do I need? Is this a pre made item I can purchase?

Provided you have the 3.6L engine:

for example, one of these:

https://www.amazon.com/InstallGear-...d=1&keywords=fused+wire&qid=1604179537&sr=8-5

always use a fused device like this and connect it to N1 and either N2 or the positive lead of the main battery

run this with ESS off

 

[Htfan]

Thanks for writing this up, lots of good learning info here.

I do not know if my 2018 has the PCM patch, is there e way on the vehicle to find out, or do i need to take it to a dealer?

For the N1 N2 jumper, what part do I need? Is this a pre made item I can purchase?

I believe you can buy these pre-made but are really a cheap diy project too. Here's a sample picture below.

You can use fuse holders like in the Amazon link Gee-pah provided above and crimp your own end connectors. . This image also shows wings nuts used for securing to the N1 and N2 terminals.

By the way, you can still run ESS with this jumper attached and the ESS battery disconnected. It uses the main battery only.

Check your recent service paperwork to see if the TSB has been applied to your 2018. I don't believe there is a way to view that specific information on your vehicle without propriety service tools. This is a dealership thing.

 

[Gee-pah]

Hey Jeff. Thanks for taking the time to write this up.

I do though think there needs to be an understanding of what is going on, and its implications by those that adopt this approach.

This is NOT to throw a monkey wrench into your ideas. Rather, it is to explain what's happening and the implications/contraindications of this design--at least as I best understand what I think you've done.

Correct me if I am wrong Jeff but it seems like on your main battery's negative/ground post you have added a device that allows the negative/ground wire from the ESS/Aux battery to be temporarily disengaged from the main battery's negative post--where it normally connects.

This is fine, but for some 3.6L owners it is mandatory that your fused jumper between the N1 and N2 terminals on the Power Distribution Center (PDC)--or N1 and the main battery positive post (same exact thing) be there as well or that 2018 won't crank. Again I think you appreciate this by your talk of the TSB 18-092-19 flash I discuss below, I just want to make that clear to the masses.

It's not that you said differently.

Here's the skinny. All 3.6L JLs test the ESS/Aux battery in isolation prior to cranking the engine. In 2018 3.6L JLs that haven't been flashed with the TSB 18-092-19 update you refer to, if the ESS/Aux battery doesn't pass this test the vehicle won't crank. It makes no difference whether the main battery is fully charged.

If you have a 2019 model year 3.6L JL or greater, or a 2018 with this flash, and your ESS/Aux battery lacks charge during this isolation test of its power I describe above, the vehicle will throw the diagnostic code you report, and upon an operator's subsequent attempts to crank the vehicle, switch over to the main battery to attempt to the crank.

Mind you, in any model year 3.6L JL, if the ESS/Aux battery passes this test, both batteries are connected in parallel by the vehcile to energize the crank. Baring Jeff's hack, all 3.6L JL model year vehicles keep the batteries in parallel at all times but for ESS events and the aforementioned instant at cold crank.

By Jeff placing a fused jumper on terminal N1 of the Power Distribution Center (PDC) that black box on top and in back of the engine bay near the passenger's seat, he has connected to the ESS/Aux battery. The other end of the fused jumper, attached to N2, or the main battery's positive terminal (it makes no difference) makes any vehicle test of the ESS/Aux battery a test that is of the composite voltage of both batteries.

That said, disconnect the ESS/Aux battery at the negative post of the main battery and Jeff has created a 3.6L JL where the ESS/Aux battery has been taken out of the loop, and is solely run on one main battery.

The tests of the ESS/Aux battery upon startup, because of Jeff's wiring change have fooled the 3.6L JL into thinking that it's testing the ESS/Aux battery when it's really testing the main battery.

Finally, when using this setup, it is advised to not allow ESS to engage.

Here's why:

In the factory setup, with your foot on the brake at a traffic light and all other ESS conditions met (i.e. you're not in a manual gear in an automatic, the steering wheel isn't turned, the engine is warmed up, etc.) the vehicle will test the ESS/Aux battery for an even higher threshold of voltage than needed to effect that cold crank. If this is met the vehicle will isolate the batteries, turn off the engine, and run appliances off of the ESS/Aux battery, monitoring it continually. If it's voltage dips too low, the ESS event is ended before the operator takes their foot off the brake, the batteries are reconnected, and the engine is cranked mostly with the power of the preserved main battery, so the alternator can charge both batteries.

Now let's look at what happens under Jeff's wiring--which is NOT a critique of his ideas, just why ESS is best not run with it enabled and an explanation of what's happening in this wiring scheme.

In Jeff's system, if all the criterion for engaging ESS are met, as usually the vehicle goes through the motions of checking the ESS/Aux battery's voltage both prior and during an ESS event, but given his wiring change the 3.6L JL is really testing only the main battery.

Assuming that main battery has power, the ESS event engages. If voltage dips too low, as usual, the vehicle switches the wiring to join both batteries and crank, only with Jeff's wiring the only battery is the main one--the very one depleted in the ESS event (NOT the separate ESS/Aux battery designed to bear this load to preserve the main battery for the crank) and engine cranking is threated.

With the jumper between N1 and N2 intact, but Jeff's changes at the main battery's negative post not installed (or engaged) what you've done is parallel connect both batteries 100% of the time. This too is a situation best contraindicated for running ESS as you will be taxing the main battery during ESS events in this setup too, only less because the ESS/Aux battery IS brought into the "electrical fold" of things.

I hope this educates. It is NOT my intention to be a smart ass. Jeff, you are a good guy; we've spoken privately before about the EZ Trunk you introduced to the forum.

Peace.

I received a very valid inquiry to the above where someone asked why running ESS with either both batteries connected in parallel all the time, or the main battery being the only battery connected is a bad idea--not because they didn't get the concepts above--but rather because other vehicles have ESS systems with one battery..

..a very fair question

The answer is that it has to do with the way the ESS system is designed by the manufacturer of each vehcile.

In the 3.6L JL Wrangler's case, because of the 2 battery setup, it is *possible* (I have not tested the limits of this either in my driveway or worse on the street where I could get stuck) that the threshold for when the vehicle shuts off an ESS event before the operator takes their foot off the brake is a lower voltage than in one battery designed ESS systems because FCA designed the 3.6L JL system to preserve the main battery in an ESS event to bear the ox's load of the engine crank's electrical demands on the starter.

It is possible that in single battery ESS systems that the threshold for ending an ESS event before the operator takes their foot off the brake is at a higher voltage that won't comprise the success of the engine crank.

Is it possible that FCA's voltage thresholds here--themselves subject to change with a future dealer flash from what those thresholds are today--are more than enough to run ESS on the main battery--especially depending upon your (aftermarket) appliance load during ESS events.

It's just this poster's opinion that it's not worth experimenting but maybe on one's own property. If you want to run ESS, I feel that keeping the wiring as per factory, or installing the Genesis system is your play.

The latter will give you at most 6 ESS events per cold engine crank. As discussed elsewhere on this forum, the Genesis system will cause the 3.6L JL to "see" similar voltages on the two batteries. And when the system sees this 6 times per crank, it assumes something is wrong and shuts off the ESS system on that trip.

This is not a bad design. Seeing identical voltages on each battery can suggest a faulty wiring situation to the 3.6L JL's computer where the batteries are hooked up in parallel and producing a composite voltage of both batteries despite which battery is tested independently; not a composite voltage as a byproduct of a user installed wiring scheme that permanently connects the batteries or takes one of the batteries out of the electrical system of the vehicle.

 

[OldGuyNewJeep]

THat is GREAT! Where can I get that part?

https://www.amazon.com/dp/B07JZ8MKL2/

 

[Htfan]

https://www.amazon.com/dp/B07JZ8MKL2/

Yes, that's the one. Same Amazon item I posted earlier in the thread

 

[TCogs1]

So great thread and information, allow me to start with a big thank you... Thank you for educating me...

I too am not happy with the FCA or Genesis design (warranty void)...

I too have experienced Jeep (JLRU 2018) shut downs in the middle of an intersection, both stock AGM batteries dropping a cell, over time (<10 volts each) and less than proactive support from FCA on this issue. Meaning Jeep cares is a joke.. Lets not get me started on that...

Bottom line, if we modify anything, the dealer and FCA are clear, it will void the warranty.. thus i have installed better AGM batteries, but the risk is still there..

Thus my question.. If I introduce a third "power" source (>500 amp hours) as a back up, so that my winch and other accessories are not attached - comingled with the Jeep system, yet available for a "jump" in the event of a Jeep failure, how best should that be done?

I have been working with engineers at Victron.. we have a few ideas.. with a simple Clamp on "jump" when needed..

My use case is weeks off grid in the Sierras..

Thanks in advance of your thoughts..

TC

 

[Htfan]

So great thread and information, allow me to start with a big thank you... Thank you for educating me...

I too am not happy with the FCA or Genesis design (warranty void)...

I too have experienced Jeep (JLRU 2018) shut downs in the middle of an intersection, both stock AGM batteries dropping a cell, over time (<10 volts each) and less than proactive support from FCA on this issue. Meaning Jeep cares is a joke.. Lets not get me started on that...

Bottom line, if we modify anything, the dealer and FCA are clear, it will void the warranty.. thus i have installed better AGM batteries, but the risk is still there..

Thus my question.. If I introduce a third "power" source (>500 amp hours) as a back up, so that my winch and other accessories are not attached - comingled with the Jeep system, yet available for a "jump" in the event of a Jeep failure, how best should that be done?

I have been working with engineers at Victron.. we have a few ideas.. with a simple Clamp on "jump" when needed..

My use case is weeks off grid in the Sierras..

Thanks in advance of your thoughts..

TC

You're very welcome! Glad it helped. The information/idea was based on several other great threads on this forum.

I haven't introduced a third power source yet myself other than a battery tender when I'm parked (both plug in and solar). However many others on this forum have. Here's one of the threads about "overlanding" :

https://www.jlwranglerforums.com/forum/threads/overlanding-battery.31628/

Let us know what you come up with!

 

[Gee-pah]

So great thread and information, allow me to start with a big thank you... Thank you for educating me...

I too am not happy with the FCA or Genesis design (warranty void)...

I too have experienced Jeep (JLRU 2018) shut downs in the middle of an intersection, both stock AGM batteries dropping a cell, over time (<10 volts each) and less than proactive support from FCA on this issue. Meaning Jeep cares is a joke.. Lets not get me started on that...

Bottom line, if we modify anything, the dealer and FCA are clear, it will void the warranty.. thus i have installed better AGM batteries, but the risk is still there..

Thus my question.. If I introduce a third "power" source (>500 amp hours) as a back up, so that my winch and other accessories are not attached - comingled with the Jeep system, yet available for a "jump" in the event of a Jeep failure, how best should that be done?

I have been working with engineers at Victron.. we have a few ideas.. with a simple Clamp on "jump" when needed..

My use case is weeks off grid in the Sierras..

Thanks in advance of your thoughts..

TC

Thomas:

That's an interesting approach--the 3rd battery--that has me recognizing what questions need to be answered--more than best how to answer them or what factors lead to the best answer: which may vary among owners.

To make what I said clearer, to my mind the questions that need to be answered are "how does this 3rd battery connected to the other 2 (at least on the 3.6L) and when?"

Any permanent parallel connection will increase overall amp hours but need to also address if the alternator can handle such loads. Such permanent connections are a double edge sword: they serve to amplify the power limitations of the other batteries, but can also be drained by weaker batteries when the vehicle is at rest, or if such a 3rd battery becomes defective, drain the other two.

So then the question becomes one regarding when the batteries are paired or isolated, and if the vehicle, when cranked, or even supplemented by external charger, has capacity to charge all three.

I might be inclined here to examine Genesis' model for connection and separation, both automatic and manual override and take the best parts of it that suit your needs.

 

[TCogs1]

Thomas:

That's an interesting approach--the 3rd battery--that has me recognizing what questions need to be answered--more than best how to answer them or what factors lead to the best answer: which may vary among owners.

To make what I said clearer, to my mind the questions that need to be answered are "how does this 3rd battery connected to the other 2 (at least on the 3.6L) and when?"

Any permanent parallel connection will increase overall amp hours but need to also address if the alternator can handle such loads. Such permanent connections are a double edge sword: they serve to amplify the power limitations of the other batteries, but can also be drained by weaker batteries when the vehicle is at rest, or if such a 3rd battery becomes defective, drain the other two.

So then the question becomes one regarding when the batteries are paired or isolated, and if the vehicle, when cranked, or even supplemented by external charger, has capacity to charge all three.

I might be inclined here to examine Genesis' model for connection and separation, both automatic and manual override and take the best parts of it that suit your needs.

Thank you for the effort... I forgot to mention I am leaning toward two q-cell 380 as another charging source via the victor on dc to dc inverter-pv manager. Thus the loads to the alternater would be reduced. Besides the mopar-warn winch does more harm to the stock agm batteries, than anything else.

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