3.6L ESS Aux Battery Bypass

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Jebiruph

Jebiruph

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I carry the fused jumper in my glove box and have wing nuts to install I also put my JL on a Deltran Tender Plus once a month for 24-36 hrs, it’s usually a solid green in less than 18 hrs but I leave.
Normally coming off the tender my batteries are in the 13.2 range so when starting the EVIC display shows 12.7 as the alternator is not putting out that much but within 24-36 of sitting it normally shows 13.5 but if I take it on a long drive it will slowly creep down toward 12.8-13, I keep ESS bypassed all the time and doubt I will ever use it.

@Jebiruph i have a question and that would be I have looked at t(e research you have done and as curious if the ESS battery does could one just run with the jumper installed all the time with the ESS negative disconnected, this would be having ESS disabled by what ever method one chooses
Yes, that is how I tested the jumper, with the aux (ESS) negative disconnected. ESS still works like this unless you disable it, everything is just running on one battery like the Cherokee's do. Realize that the two battery system is probably designed to fix issues with the single battery system while introducing it's own problems.





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Jebiruph

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In this configuration , does the aux battery charge?
No, but it shouldn't discharge either, except as a battery in storage might have the charge bleed off over time. You could occasionally check the aux voltage and reconnect as needed, or just occasionally reconnect without checking the voltage.
 

WranglerMan

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Yes, that is how I tested the jumper, with the aux (ESS) negative disconnected. ESS still works like this unless you disable it, everything is just running on one battery like the Cherokee's do. Realize that the two battery system is probably designed to fix issues with the single battery system while introducing it's own problems.
Its not that I have issue with having two batteries it’s the location of the second ESS battery that is a PITA to get to, normally as most know if a main battery goes out it’s not that much trouble to remove and replace, heck I have even replaced a main battery in a vehicle in the parking lot of Autozone in a pinch but it’s pretty impossible to do this with the ESS battery and accessing it from below as some have suggested looks like even a bigger pain then going in from the top

I have priced out the Genesis system but that’s way over the top for cost to eliminate the ESS battery so for now I will keep ESS bypassed and carry my jumper and wing nuts and when it craps out just use the jumper and disconnects the ESS negative
 
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c2m2h3

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Can't thank you guys enough. I appreciate the explanations and of course Jerry's info ! Thanks !!
 

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I disconnected the PCR last night using these photos from the other thread, then disconnected my Aux negative. Went for a quick drive and ESS worked just fine 9only once before I disabled it). Than I charged the main battery with a smart charger (NOCO Genuis 3500 set on AGM mode), went to 100% in a bout an hour whereas the other day it took several hours to charge both batteries. This morning, about a 30 minute drive to work, I'm still sitting at 14.0 - 14.2 volts. My next step is going to be to disconnect the negative from the main for a few hours and see if resting the system helps the chargin get back to where it should be. I'm concerned about overcharging the main battery.

Here are the pics I used to find the PCR relay and unplug. I had a large connector in the way that isn't in the pics which made it difficult, and for anyone that tries this you have to press on the grey tabs with a small screwdriver from underneath to get it to release and then just work it out.

Here's some better pictures of the PCR location, taken with the fender flare removed. I added these pictures to post #2.

pcr location b.jpg


pcr location 2b.jpg
 

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I disconnected the PCR last night using these photos from the other thread, then disconnected my Aux negative. Went for a quick drive and ESS worked just fine 9only once before I disabled it). Than I charged the main battery with a smart charger (NOCO Genuis 3500 set on AGM mode), went to 100% in a bout an hour whereas the other day it took several hours to charge both batteries. This morning, about a 30 minute drive to work, I'm still sitting at 14.0 - 14.2 volts. My next step is going to be to disconnect the negative from the main for a few hours and see if resting the system helps the chargin get back to where it should be. I'm concerned about overcharging the main battery.

Here are the pics I used to find the PCR relay and unplug. I had a large connector in the way that isn't in the pics which made it difficult, and for anyone that tries this you have to press on the grey tabs with a small screwdriver from underneath to get it to release and then just work it out.

You are not going to over charge the main battery, you have to remember these newer vehicles use what they call a “ smart charging algorithm so if the battery is near fully charged the relay senses the voltage and tells the alternator not to put out that much voltage so your battery either needs to be charged or the relay could be bad or the battery could be taking a crap but the only way to tell what the charge is to put a meter on the battery itself as you cannot go by what the EVIC display as that displays the alternator input.

I put my JL on a tender once a month and it normally takes 1/2 a day or so to go solid green and the displayed voltage is like 12.8 and normally stays in that range for a day or so and then hovers around 13.2 but if it sits for say a day or two without starting then the displayed EVIC voltage is 14.3 and it stays there until I take it for a lengthy drive and then the more I drive it the lower it drops, it seems that if left parked the onboard computer including tasers, smart stop/start modules all cause a minimal parasitic draw so in my mind that’s what causes the spike to over 14 when sitting but you have to remember that back before all this smart charging crap that alternators all put out 14+ volts all the time so every time your vehicle was running it was being charged at that rate but all in the sake of technology theses makers need to do all they can you squeeze those mileage rating so the less load on the alternator the better the mileage.

I personally have quit looking at the voltage as there seems no rhyme or reason for what voltage is displayed but what I do is occasionally pull the negative leads and check the voltages of each battery separately and they are normally in the 12.7 range which is fully charged and I have no warnings or evil messages displayed and I do test for correct ESS operation occasionally and it’s been 100%

Here are some numbers to compare to your battery


upload_2019-11-6_13-56-29.png
 

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You are not going to over charge the main battery, you have to remember these newer vehicles use what they call a “ smart charging algorithm so if the battery is near fully charged the relay senses the voltage and tells the alternator not to put out that much voltage so your battery either needs to be charged or the relay could be bad or the battery could be taking a crap but the only way to tell what the charge is to put a meter on the battery itself as you cannot go by what the EVIC display as that displays the alternator input.
I understand and that is my concern - the battery should be fuly charged but the system is still trying to charge it. After driving home today, where the voltage stayed at 14 (13.9 with A/C on) and when I got home the main battery was 12.65 when I checked with a meter. The Aux is at 12.54 when I checked, but it is disconnected. My concern is that the relay or something has an issue and it is not sensing to stop charge the battery even though it is full.

My next step is going to be to disconnect the main and let it sit for awhile to see if the corrects it.
 

moodywizard

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Man, all those jeeps before us were over charging their batteries this whole time...if only they knew.
 

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Man, all those jeeps before us were over charging their batteries this whole time...if only they knew.
Exactly, before all of this so called “smart technology” the vehicles alternator constantly kicked out 14+ volts all the time but now the voltage is supposed to be monitored and the charging voltage is adjusted accordingly but when say a relay fails that senses the voltage it’s going to send a full output from the alternator to the battery, they say doing this shortens the life of the battery but by how much who knows and honestly who cares as changing the main battery is pretty easy, now changing that ESS battery is another story
 

cbrenthus

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Exactly, before all of this so called “smart technology” the vehicles alternator constantly kicked out 14+ volts all the time but now the voltage is supposed to be monitored and the charging voltage is adjusted accordingly but when say a relay fails that senses the voltage it’s going to send a full output from the alternator to the battery, they say doing this shortens the life of the battery but by how much who knows and honestly who cares as changing the main battery is pretty easy, now changing that ESS battery is another story
Yes, that's true, but I thought AGM batteries were more sensitive to charging needs? I have to admit I'm a bit gun shy at the moment because my bike's battery starting going bad only a year after purchase, and I had it replaced under warranty right before the 2 year warranty was up - it's an AGM and I never had issues like that before. Anyway, I disconnected my battery in the jeep overnight last night to see if that changes anything and will go for a drive later.
 

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Yes, that's true, but I thought AGM batteries were more sensitive to charging needs? I have to admit I'm a bit gun shy at the moment because my bike's battery starting going bad only a year after purchase, and I had it replaced under warranty right before the 2 year warranty was up - it's an AGM and I never had issues like that before. Anyway, I disconnected my battery in the jeep overnight last night to see if that changes anything and will go for a drive later.
AGM can be a bit more sensitive to charging as over hearing from these high amp chargers can cause the battery to gas off and liquids cannot be replaced as they are so called maintenance free and also should no be discharged below 50% so this is why I keep my JL on a tender when it’s going to be parked several days and my tender charges at a very low rate and once charged goes into float mode and monitors

You also have to be mindful that these new vehicles have active brains, they do go into a rest mode but they still have a small parasitic draw and then if you add things like a Tazer or Smart Stop/Start they to draw a small amount of power and all of this adds up so it’s best to buy a tender and whenever it’s going to be parked just pop it on the tender and if you have a quick connect it literally only takes about 5 mins to hook up or disconnect

Here is a site that has a ton of info

https://www.batterystuff.com/
 

redracer

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I like this approach - which is the relay for the ESS? Are you getting any lights on your dash?
the relay is behind the passenger side tire mounted against the firewall.
No lights have appeared. I have been perfectly happy with this solution.
 

cbrenthus

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the relay is behind the passenger side tire mounted against the firewall.
No lights have appeared. I have been perfectly happy with this solution.
Thanks, I found it in another thread and disconnected last weekend. I was disappointing, though, as I thought that disconnecting the relay would disable ESS permanently, but it appears that it only prevents the batteries from being separated, thus having the same result as the jumper. No worries though, I just hit the button, and I'm planning on doing this to my wife's pacifica at the first oil change.
 

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I completely removed the auxiliary battery and wiring about 2 weeks ago due to a bad aux battery but learned something important if you do it this way. A 30 amp fuse is not enough to carry the max load of everything powered by the N1 terminal and when that fuse blows under those conditions it definitely lets you down and you don't have emergency flashers, windows won't roll up and down, etc. I did an amperage check and I was seeing 30.9 amps with heater blower at full blast and radio at about half volume, so I came off of N3 which originally fed the aux battery and is fused at 150A and ran a 6 gauge jumper to N1, I feel more comfortable doing it that way instead of a jumper from N2 to N1 which would have no fusing and could carry whatever current the main battery could provide.
 

c2m2h3

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So instead of N1 to N2, you ran a 6 gauge wire to N3 ? And with what size fuse ?
 

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