Jumperless aux battery/PCR bypass

[ShadowsPapa]

The electrical studs are either M8 1.25 or M6 1.0.

Yeah, I was thinking the bolts along the fender when I put M5
I knew one was 6 because I dug a M6 out of my stash of flanged nuts for my cables.

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[Lunentucker]

A friend of mine had his AUX battery deplete the main battery and then it went over to his Mustang next to it in the garage and depleted that too.
When he caught it the next morning it was trying to connect itself to his cordless leaf blower.
True story. He's got the video saved from his security camera.

 

[Maximus Gladius]

A friend of mine had his AUX battery deplete the main battery and then it went over to his Mustang next to it in the garage and depleted that too.
When he caught it the next morning it was trying to connect itself to his cordless leaf blower.
True story. He's got the video saved from his security camera.

I believe it! It’s the AI system that grows what it needs.

 

[ShadowsPapa]

A friend of mine had his AUX battery deplete the main battery and then it went over to his Mustang next to it in the garage and depleted that too.
When he caught it the next morning it was trying to connect itself to his cordless leaf blower.
True story. He's got the video saved from his security camera.

So it hadn't gotten to the camera yet? What about his cellphone battery?

 

[obrianmcc]

My AUX has been deleted for approx 9 months ... no issues. System works as intended. It will cycle six times and fault, but resets at the next start up. I'll be doing the same to my wife's JL when the AUX starts to become problematic.

 

[IanNubbit]

The issue with this is it keeps the Aux battery connected at all times. The relay is normally closed, not open. So if the battery fails, all the same issues are still susceptible.

 

[ShadowsPapa]

The issue with this is it keeps the Aux battery connected at all times. The relay is normally closed, not open. So if the battery fails, all the same issues are still susceptible.

You are supposed to at least pull the aux battery negative cable off of the IBS so that the battery is still in the truck, but not connected. You could fully remove it making bloody well sure the positive terminal you remove from the aux battery is totally insulated. But taking the aux battery ground cable off the main battery negative at the IBS should do it. That way there's not a complete circuit to the aux. Doesn't matter if only the positive is still connected.

Pulling the fuse allows you to disconnect that ground and not kick an error on startup. It can't run the start-up test by opening the PCR.

 

[IanNubbit]

You are supposed to at least pull the aux battery negative cable off of the IBS so that the battery is still in the truck, but not connected. You could fully remove it making bloody well sure the positive terminal you remove from the aux battery is totally insulated. But taking the aux battery ground cable off the main battery negative at the IBS should do it. That way there's not a complete circuit to the aux. Doesn't matter if only the positive is still connected.

Pulling the fuse allows you to disconnect that ground and not kick an error on startup. It can't run the start-up test by opening the PCR.

I just yesterday finally got time to remove it completly. My whole mission with the truck since day one has been remove everything electrical I dont need without any codes. I want a simple truck lol. I did it a way I havent seen yet, its free and didnt require making or cutting any cable, which I will do eventually when I get more time so I can remove the PCR relay and all of its cabling.

I personally removed the battery all together, removed the ground wire from the vehicle all together (requires cutting 3 ziptie retainers and some harness tape but no wire is shown, all of the harness wrap removed has the cables underneath still harness wrapped). Pulled the positive cable up from under the fuse box entirely. Broke the small tabs off the end of the AUX battery side of the Positive Aux battery cable, and attached it to the Main battery positive post closest to the firewall. This was the best free way I could think of and under the hood looks almost completly stock still.

Once I get time, I will create a short cable that goes on that same post of the postive terminal closest to the firewall, and instead of just going to Spot N2 on the fuse box it will go to N1, N2, and N3. This will make 1 short (8" at most) cable that supplies power to both the power in sections of the fuse box, along with the N3 location which will essentially allow it to "charge" like it would the AUX battery normally. I think I can get away with not having the N3 alltogether as I can then remove the PCR and the fuse mentioned in this post. Theoretically there should be no issues with that because there is no "sense" logic or circuit in the system. Just power to the relay to open the circuit to the Aux. But again, that will require testing.

 

[Mr._Bill]

Removing the ESS battery doesn't make the truck more simple. The ESS system is always active and cannot be disabled or removed. It will always be looking for the ESS battery. Removing any part of the ESS system will cause any future warranty claims for electrical to be denied.

 

[ShadowsPapa]

Once I get time, I will create a short cable that goes on that same post of the postive terminal closest to the firewall, and instead of just going to Spot N2 on the fuse box it will go to N1, N2, and N3. This will make 1 short (8" at most) cable that supplies power to both the power in sections of the fuse box, along with the N3 location which will essentially allow it to "charge" like it would the AUX battery normally. I think I can get away with not having the N3 alltogether as I can then remove the PCR and the fuse mentioned in this post. Theoretically there should be no issues with that because there is no "sense" logic or circuit in the system. Just power to the relay to open the circuit to the Aux. But again, that will require testing.

Ya sort of got me on that first part.......... the main battery charges like the aux battery already.
Current from the alternator goes through the high current fuse array bus - and to the main battery positive via N2. Connecting it to N3 as well won't gain a thing.
N2 and N3 come off the same bus bar, the only difference is there's a fuse in N3 and not N2. There's already a fuse at N7 so that output from the alternator is fused.
What you are doing is just rearranging the wires - it won't be any different than those who only disconnect the aux negative cable from the main battery and pull F42 to prevent PCR from opening.
Electrically you are doing nothing different other than removing the PCR wiring and connecting main battery + directly to N1 instead of going through the PCR wiring. That's the only difference. All you need to do is connect N1 to N3 terminal. Leave the rest alone.

 

[IanNubbit]

Ya sort of got me on that first part.......... the main battery charges like the aux battery already.
Current from the alternator goes through the high current fuse array bus - and to the main battery positive via N2. Connecting it to N3 as well won't gain a thing.
N2 and N3 come off the same bus bar, the only difference is there's a fuse in N3 and not N2. There's already a fuse at N7 so that output from the alternator is fused.
What you are doing is just rearranging the wires - it won't be any different than those who only disconnect the aux negative cable from the main battery and pull F42 to prevent PCR from opening.
Electrically you are doing nothing different other than removing the PCR wiring and connecting main battery + directly to N1 instead of going through the PCR wiring. That's the only difference. All you need to do is connect N1 to N3 terminal. Leave the rest alone.

i think ill disconnect the fuse for the PCR and takeoff N3. Run it for like a month, if all is good. Ill pull the relay and its cableling. Yes just pulling off the Aux ground has the same effect i like removing unnecessary parts, so they are out of the way to make everything easier to work on. Thats why the door harnesses are gone, rear sway bar, gone. If i don't use it, and the truck is perfectly functional without it, its coming off the truck

 

[Andy29847]

The ESS battery is there to keep the computers stable during ESS events. The Main and ESS batteries are only separated from each other during ESS events. The rest of the time they are paralleled together. The Main battery is the one that drives the starter.

There seems to be a lot of concern about the batteries and very little concern about exposing the "computer" to electrical fluctuations that might occur during a stop start using just one battery. Common sense would seem to indicate that if the manufactures thought running stop start on just one battery was OK, they would only provide one battery. While I mostly understand how starting solenoids on older cars and truck isolated some electrical equipment during starts, I am not sure how the system in JL Jeeps operates.

 

[jebiruph]

There seems to be a lot of concern about the batteries and very little concern about exposing the "computer" to electrical fluctuations that might occur during a stop start using just one battery. Common sense would seem to indicate that if the manufactures thought running stop start on just one battery was OK, they would only provide one battery. While I mostly understand how starting solenoids on older cars and truck isolated some electrical equipment during starts, I am not sure how the system in JL Jeeps operates.

I don't agree with the protecting the "computer" from electrical fluctuations theory. What's the difference between the electrical fluctuations when doing a cold start as opposed to an ESS warm start? Wouldn't the "computer" be exposed the the same electrical fluctuations during any start? I would think that adding the second battery and the controling relay would cause more electrical fluctuations than running a single battery system. Plus, the proper fix for electrical fluctuations is a capacitor, not a secondary battery system.

There are JL owners that have been running a single battery for years and I have never seen a reported electrical fluctuation issue. Cherokee's like my wife's 2019 have always had a single battery ESS system and during the short time I spent on that forum, I never saw reports of an electrical fluctuation issue. What Cherokee owners reported was the single battery failing during an ESS restart and stranding them in traffic, which is the problem the 2 battery system addresses by not using the starting battery to power the electronics during an ESS event.

And then there is the Genesis dual battery system that some people install to eleminate the small factory aux battery. What the Genesis system does is convert the 2 battery ESS system to a single battery ESS system and although I've seen issues reported with the Genesis system, I've never seen an ESS induced electrical fluctuation issue reported.

 

[sharpsicle]

I don't agree with the protecting the "computer" from electrical fluctuations theory. What's the difference between the electrical fluctuations when doing a cold start as opposed to an ESS warm start? Wouldn't the "computer" be exposed the the same electrical fluctuations during any start? I would think that adding the second battery and the controling relay would cause more electrical fluctuations than running a single battery system. Plus, the proper fix for electrical fluctuations is a capacitor, not a secondary battery system.

There are JL owners that have been running a single battery for years and I have never seen a reported electrical fluctuation issue. Cherokee's like my wife's 2019 have always had a single battery ESS system and during the short time I spent on that forum, I never saw reports of an electrical fluctuation issue. What Cherokee owners reported was the single battery failing during an ESS restart and stranding them in traffic, which is the problem the 2 battery system addresses by not using the starting battery to power the electronics during an ESS event.

And then there is the Genesis dual battery system that some people install to eleminate the small factory aux battery. What the Genesis system does is convert the 2 battery ESS system to a single battery ESS system and although I've seen issues reported with the Genesis system, I've never seen an ESS induced electrical fluctuation issue reported.

The difference is that on a cold start, not all the systems are designed to be on, so while the truck starts it can selectively protect those systems that it doesn't want the fluctuations to get to by keeping them off. Cold starts don't run everything (on purpose) which is why there's less worry. Vehicles have been doing this for decades, in part for electronics protection.

In contrast, on ESS events, all systems are staying on, so they need another mode of protection against possible voltage fluctuations since you can't do the same things to protect as you can on a cold start. That's the whole reason this system was developed. Coupled with the idea to not strand you based on just 1 battery, you get this two-battery system in order to provide isolation and reliability. As you said, the one-battery systems showed issues with reliability, so this was made to compensate. To keep the truck systems 100% on during an ESS start but not strand you due to ESS. All this is a scenario unique to ESS.

I totally agree that a single-battery system is simpler. But a lot of what you talked about above is just false. ESS events and cold starts are not the same. An ESS battery doesn't cause more fluctuations, it causes less. The switching is introducing a like-for-like power source that's been maintained in parallel during operation, has the same voltage. It isolates the voltage drop the starter introduces. Batteries can be viewed as large capacitors in this application if you prefer. Larger, denser, more controlled capacitors. However here, the quick discharge nature of capacitors is actually what you don't want when you isolate like this.

The issues arise when that ESS battery is no longer like-for-like. When the system detects this, it disables ESS. Thankfully you don't get stranded though, like in the Cherokee system, you get a warning, and you go get service. That's when batteries tend to get replaced. But this all centers around voltage and the voltage fluctuations that current draw creates.

Kits like the Genesis no longer have an ESS battery. It's a bit unfair to state it like they do. In reality they have a larger main battery which can withstand the starter draw better due to the significant increase in capacity. Isolation of one battery no longer happens here. Clearly it works, yes, but it's not an ESS battery anymore and no longer has the benefits of the original ESS system. If the batteries go bust or introduce unacceptable voltage fluctuations on a Genesis during ESS, you're stranded, just like the Cherokee's system. There's no isolation for protection and no back-up. I'm not saying the Genesis is begging for problems, but it's important to know what the differences are and why.

 

[jebiruph]

The difference is that on a cold start, not all the systems are designed to be on, so while the truck starts it can selectively protect those systems that it doesn't want the fluctuations to get to by keeping them off. Cold starts don't run everything (on purpose) which is why there's less worry. Vehicles have been doing this for decades, in part for electronics protection.

In contrast, on ESS events, all systems are staying on, so they need another mode of protection against possible voltage fluctuations since you can't do the same things to protect as you can on a cold start. That's the whole reason this system was developed. Coupled with the idea to not strand you based on just 1 battery, you get this two-battery system in order to provide isolation and reliability. As you said, the one-battery systems showed issues with reliability, so this was made to compensate. To keep the truck systems 100% on during an ESS start but not strand you due to ESS. All this is a scenario unique to ESS.

I totally agree that a single-battery system is simpler. But a lot of what you talked about above is just false. ESS events and cold starts are not the same. An ESS battery doesn't cause more fluctuations, it causes less. The switching is introducing a like-for-like power source that's been maintained in parallel during operation, has the same voltage. It isolates the voltage drop the starter introduces. Batteries can be viewed as large capacitors in this application if you prefer. Larger, denser, more controlled capacitors. However here, the quick discharge nature of capacitors is actually what you don't want when you isolate like this.

The issues arise when that ESS battery is no longer like-for-like. When the system detects this, it disables ESS. Thankfully you don't get stranded though, like in the Cherokee system, you get a warning, and you go get service. That's when batteries tend to get replaced. But this all centers around voltage and the voltage fluctuations that current draw creates.

Kits like the Genesis no longer have an ESS battery. It's a bit unfair to state it like they do. In reality they have a larger main battery which can withstand the starter draw better due to the significant increase in capacity. Isolation of one battery no longer happens here. Clearly it works, yes, but it's not an ESS battery anymore and no longer has the benefits of the original ESS system. If the batteries go bust or introduce unacceptable voltage fluctuations on a Genesis during ESS, you're stranded, just like the Cherokee's system. There's no isolation for protection and no back-up. I'm not saying the Genesis is begging for problems, but it's important to know what the differences are and why.

Good point about the difference between a cold start and warm start, I'll give you that one.

I have correctly described the Genesis as a single battery ESS system and that single battery is actually a smaller battery than the factory battery.

What is your source that the 2 battery system was developed to protect against possible voltage fluctuations as opposed to just conserving main battery power for the restart?

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