3.6L ESS Aux Battery Bypass

cbrenthus

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Sorry I missed all the activity on this thread, I was busy buying a Gladiator.

@cbrenthus , I think you're mostly right on everything. Unplugging the PCR is mostly the same as using the jumper. But if the ESS high capacity fuse is blown, unplugging the PCR won't help, but the jumper will. The jumper also makes it easier to go back and forth by just installing/removing the fuse as opposed to crawling under the jeep to unplu/plug in the PCR.

The problem the fused jumper solves is when a bad aux battery can't be jump started. Early on, people were getting towed to the dealer for a dead battery. It wasn't until several months later that it was found that unplugging the PCR could also work. Since I have a fused jumper, I still prefer the jumper as opposed to crawling underneath to unplug the PCR.
Good points - I wasn't aware of the ESS high capacity fuse. My other question is why the vehicle won't jump start with a dead Aux? Is it because I truly bad Aux, that is maybe shorted, sucks all the power away thus not letting the main charge up to start? Because why not just disconnect the Aux and get an ESS error?

I'm imagining the JT ESS will be identical, since it is the same system as the Pacifica as well.





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WranglerMan

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Maybe the Ford Bronco will be a better design :)
 
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Jebiruph

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Good points - I wasn't aware of the ESS high capacity fuse. My other question is why the vehicle won't jump start with a dead Aux? Is it because I truly bad Aux, that is maybe shorted, sucks all the power away thus not letting the main charge up to start? Because why not just disconnect the Aux and get an ESS error?

I'm imagining the JT ESS will be identical, since it is the same system as the Pacifica as well.
If you haven't yet, check out this thread https://www.jlwranglerforums.com/forum/threads/3-6l-ess-dual-battery-consolidated-information.25377/ , it may have all the information you're looking for.
 

cbrenthus

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TimmH

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Correct me if I am wrong and am misunderstanding all of this thread, there is a lot to read, and other similar threads have my head spinning. :)

It seems from this that if you put a small jumper between N1 and N2, that you would be able to start the Jeep immediately using the main battery (Assuming it is not discharged, and your only issue of the aux battery).

Is this correct.

Other option, if both are dead, would be disconnect the negative from the main battery, jumper N1 & N2, and put a power pack on the disconnected Negative cable end, and on the main battery positive post?

Last time I had a dead battery(In my Mustang), and just so happened to not have my jumper cables in the car. I was amazed at how difficult it is to find anyone with jumper cables or willingness to help.
 

cbrenthus

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Correct me if I am wrong and am misunderstanding all of this thread, there is a lot to read, and other similar threads have my head spinning. :)

It seems from this that if you put a small jumper between N1 and N2, that you would be able to start the Jeep immediately using the main battery (Assuming it is not discharged, and your only issue of the aux battery).

Is this correct.
Maybe - from what I have read, and I have the same head spinning that you do from reading so much about it, if the batteries are dead it could mess up the start sequence, thus requiring the jumper. All the jumper does is bypass the relay that separates the batteries, thus keeping them in parallel 100% of the time.

Other option, if both are dead, would be disconnect the negative from the main battery, jumper N1 & N2, and put a power pack on the disconnected Negative cable end, and on the main battery positive post?
No - in the above scenario you are only charging the AUX battery. However, if you disconnect the AUX negative, then yes, you'll charge only the main. There shouldn't be a need for the jumper though - you'll just get a service ESS system message after starting and a yellow ESS light. I'm currently running with the Aux negative disconnected, and I love running off a single battery and no ESS. The error message and yellow light don't bother me nearly as much as I thought they would ;)

Last time I had a dead battery(In my Mustang), and just so happened to not have my jumper cables in the car. I was amazed at how difficult it is to find anyone with jumper cables or willingness to help.
These days, I wouldn't jump someone's vehicle due to all of the sensitive electronics and liability. Something is messed up on their car, you might have a lawyer call you. And likewise I wouldn't accept a jump from just anyone - only a professional or my own jumper box.
 

c2m2h3

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I have no doubt Jerry will post up some clarification. He’s been great in responding. He also has a link that sends you to another thread that explains most things. The problem is, for some of us that don’t have a whole lot of electrical experience, it can be quite overwhelming. I think the best way is to explain it step-by-step with the jumper wire and which negative terminal is disconnected and where the jump pack cables are connected. I think some of the confusion is when people try to explain why these steps are necessary. Some of us don’t really care why FCA set this ESS system up, we just want to know how to disable it and jump your vehicle (jump pack) if either or both of the batteries are dead...
 
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Jebiruph

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Other option, if both are dead, would be disconnect the negative from the main battery, jumper N1 & N2, and put a power pack on the disconnected Negative cable end, and on the main battery positive post?
I think you are describing jump starting with just the aux battery which theoretically should work. The theory is it may be quicker to jump start if you only have to over come a drained small aux battery as opposed to a drained large main battery. If you are finding all the options confusing, ignore this one as it is probably of limited value.
 
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Jebiruph

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For those that are apprehensive about the two battery system, I recommend doing a practice run with using only the main battery. Either use a fused jumper or unplug the PCR to bypass the aux battery and disconnect the aux negative cable from the main battery terminal. After you run this way for a while I think you'll gain some confidence in the system or at least your ability to overcome it's deficiencies.

Even if you have a fused jumper, you should still become familiar with disconnecting the PCR in case you come across a fellow jeeper needing aux battery assistance.
 

TimmH

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For those that are apprehensive about the two battery system, I recommend doing a practice run with using only the main battery. Either use a fused jumper or unplug the PCR to bypass the aux battery and disconnect the aux negative cable from the main battery terminal. After you run this way for a while I think you'll gain some confidence in the system or at least your ability to overcome it's deficiencies.

Even if you have a fused jumper, you should still become familiar with disconnecting the PCR in case you come across a fellow jeeper needing aux battery assistance.
So putting the fused jumper on just puts the batteries in parallel? Thereby overcoming any deficiency in the aux battery to fail start-up requirements?

Would be nice to see someone come out with a conversion kit to completely remove the aux battery, at least for those of us that don't use the ESS.
 

WranglerMan

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So putting the fused jumper on just puts the batteries in parallel? Thereby overcoming any deficiency in the aux battery to fail start-up requirements?

Would be nice to see someone come out with a conversion kit to completely remove the aux battery, at least for those of us that don't use the ESS.
In a way if you use a properly fused jumper between N1 & N2 and disconnect the ESS negative you are effectively eliminating the aux battery and can leave it long term with no ill affects, I have tested it short term and it works well but I have ESS turned off using a Smart Stop/Start module and never use ESS.

I currently run with it like it came from the factory but when my baby battery craps out I doubt I will replace it and just run my jumper full time
 

cbrenthus

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Or, as I've mentioned, if you don't like ESS and want a single battery, just disconnect the AUX negative. You'll get a message after starting to service ESS, but it goes away quickly, and the ESS light will stay on, but you don't have to hit the button anymore. I've been running like this for a month or two and love it!
 

jeepdabest

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Or, as I've mentioned, if you don't like ESS and want a single battery, just disconnect the AUX negative. You'll get a message after starting to service ESS, but it goes away quickly, and the ESS light will stay on, but you don't have to hit the button anymore. I've been running like this for a month or two and love it!
I'm confused. (often) Doesn't the Jeep need to have a good aux to start? How does that happen without jumper?
 

Dkretden

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I'm confused. (often) Doesn't the Jeep need to have a good aux to start? How does that happen without jumper?
I’m am utterly confused too (but that is my normal state). I thought that a connected aux battery was required for starting........

if this is true..... disconnect the aux negative and still be able to start and drive around, jumping a Jeep with a fully depleted aux battery will be simple: 1) disconnect the aux negative, 2) use a jumper to jump the main, 3) start it, 4) drive to get your batteries tested/fixed.......

is it really that simple?
 

WranglerMan

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I’m am utterly confused too (but that is my normal state). I thought that a connected aux battery was required for starting........

if this is true..... disconnect the aux negative and still be able to start and drive around, jumping a Jeep with a fully depleted aux battery will be simple: 1) disconnect the aux negative, 2) use a jumper to jump the main, 3) start it, 4) drive to get your batteries tested/fixed.......

is it really that simple?
Or you could run a jumper and disconnect ESS negative and just run the Jeep with the one battery but I don’t believe that the one battery will support using ESS as it’s designed but if you disable ESS kicking in by what ever means it should run fine on just one battery
 

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