3.6L ESS Aux Battery Bypass

[oliver8]

The Genesis dual battery kit deletes the aux battery, but it adds a second full size group 25 battery up higher, not sure if they make it for wrong side drivers.

Thanks Jim Lee, yes i have already talked Genesis, they only make a kit for the rhd jk and are not likely to make one for the jl.

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[LincolnSixAlpha]

Thanks Jim Lee, yes i have already talked Genesis, they only make a kit for the rhd jk and are not likely to make one for the jl.

I installed a Genesis system about a month ago, love it. Also, the fact that the motorcycle battery is now gone. I'm assuming from your comment that the Genesis system won't work in your left-hand drive due to battery placement, thinking your batteries are on the opposite side?

 

[oliver8]

I installed a Genesis system about a month ago, love it. Also, the fact that the motorcycle battery is now gone. I'm assuming from your comment that the Genesis system won't work in your left-hand drive due to battery placement, thinking your batteries are on the opposite side?

Yes none of the mounting plate brackets will match up .Thinking of getting an American adventure lab battery/compressor mount for the storage space under the back floor and setting that up as a dual battery set up for my fridge etc and removing the aux battery.

 

[LincolnSixAlpha]

Yes none of the mounting plate brackets will match up .Thinking of getting an American adventure lab battery/compressor mount for the storage space under the back floor and setting that up as a dual battery set up for my fridge etc and removing the aux battery.

Yea, that was the real reason for the dual battery to support the ARB fridge while camping, as well as eliminating that secondary motorcycle battery which would not be easily changed while offroading in an emergency situation. At a minimum, I'm hoping you're able to rectify your situation. The Australian "bush" is certainly much more far/wide and vast then the bush we have here in Az, although both are deadly.

 

[Jebiruph]

The interesting thing to me is just how shitty these auxiliary batteries must be considering how many seem to be failing in less than 2 years of use.

I was in Colorado on Imogene when one of our forum members (screen name escapes me at the moment) seemed to be having this exact issue and wound up being a trail tampon blocking travel in both directions. All I know is, once he got moved out of the way, my family and I decided considering what we'd just witnessed that it would be best to climb to the top of pass (instead of going all the way over to Ouray), then turn around...we were based out of Mountain Village above Telluride...and if he was still there (I asked if he had other people in his group, to which he replied he did) we'd help them get down the mountain. When we got back (about 45 minutes to an hour later) he was already gone.

Not confidence inspiring to say the least. Way to go Jeep.

Thanks to the OP for posting up the info. Looks like I'll be adding a jumper wire/fuse to the tool bag.

Here's my current thoughts on how to manage the batteries for an off-roading trip. Before you leave home, load test the aux battery, even if it's just disconnecting the main battery and verifying that the aux battery is able to start by itself. It wouldn't hurt to load test both batteries. Reconnect everything and use the drive to your destination to fully charge the aux battery. After you arrive and before you head off-road, use the jumper to by-pass the aux battery, then disconnect it from the system. Now it should be a fully charged back for the main battery. If the main battery dies on the trail, disconnect it and reconnect the aux battery.

One of the advantages of using a fused jumper is so you can leave the jumper installed and install/remove the fuse as needed.

 

[four low]

Now that the 3.6 is getting BSG, will it be possible to have a "by pass", or does the whole system die if the 48v dies?

 

[jeepdabest]

Yea, that was the real reason for the dual battery to support the ARB fridge while camping, as well as eliminating that secondary motorcycle battery which would not be easily changed while offroading in an emergency situation. At a minimum, I'm hoping you're able to rectify your situation. The Australian "bush" is certainly much more far/wide and vast then the bush we have here in Az, although both are deadly.

All men have learned that any bush can be costly and deadly.

 

[Jebiruph]

Here's my current thoughts on how to manage the batteries for an off-roading trip. Before you leave home, load test the aux battery, even if it's just disconnecting the main battery and verifying that the aux battery is able to start by itself. It wouldn't hurt to load test both batteries. Reconnect everything and use the drive to your destination to fully charge the aux battery. After you arrive and before you head off-road, use the jumper to by-pass the aux battery, then disconnect it from the system. Now it should be a fully charged back for the main battery. If the main battery dies on the trail, disconnect it and reconnect the aux battery.

One of the advantages of using a fused jumper is so you can leave the jumper installed and install/remove the fuse as needed.

Ok, that seems complicated, this is simpler. Install the jumper and disconnect the aux battery full time. Check the aux battery voltage every several weeks and reconnect or trickle charge to keep it charged so you always have a fully charged backup battery.

Just be aware that based on user experience with the single battery ESS system on the Cherokee, ESS wears out standard batteries quickly. If you want to use ESS with a single battery, upgrade to an AGM battery.

 

[dugal]

I have spent the last 4 days on-and-off carefully absorbing all the information in this thread. OMG what a well done wealth of useful and important data. Special kudos to Jebiruph and everyone who weighed-in. All posts were relevant and on-track and Jebiruph's responses were timely and informational put in simple terms. This thread should be a model for all threads. Thoroughly enjoyable, relevant and much appreciated. Cheers

 

[Jebiruph]

I have spent the last 4 days on-and-off carefully absorbing all the information in this thread. OMG what a well done wealth of useful and important data. Special kudos to Jebiruph and everyone who weighed-in. All posts were relevant and on-track and Jebiruph's responses were timely and informational put in simple terms. This thread should be a model for all threads. Thoroughly enjoyable, relevant and much appreciated. Cheers

Thanks for your comments, I also appreciate everyone staying on topic.

 

[WhatExit?]

Jerry, Jerry, Jerry - great stuff - thank you!

Like many, I'm on both the JL and JT Gladiator forums (I own the latter). I can easily assume the JT is no different than the JL in regard to the two batteries. BUT rather than assume, does anyone know for sure so I can follow everything in this great thread knowing it applies to my JEEP?

Also, I can't afford to spend big bucks on a Genesis kit so I'll be considering a 2nd battery in the bed of my Gladiator. I'll need to find and understand info on if/how a dual battery setup changes due to the AUX/ESS battery.

Thanks again, -Dan

 

[WhatExit?]

For my benefit and hopefully others, I've re-quoted a number of what I think are key posts to put them in one place as this thread is, at 11+ pages, quite informative and long...

I've seen quite a few posts related to failed Aux batteries causing flaky or dead electronics, stalling and failing to start/auto restart. I've come up with a simple way to temporarily bypass a bad Aux battery (also blown PCR fuse or bad PCR) and get back on the road. Warning - this post contains a lot of informed assumptions, so post your related experiences to help validate or invalidate any information I've provided.

Here's a picture of my bypass kit. The jumper is used to connect the N1 terminal to the N2 terminal. I wanted to be able to install the jumper securely, but still be able to quickly disconnect it. A fused jumper seemed to be the best and cheapest way to go. Removing the fuse is a simple way to disconnect the jumper and it protects against overloading the wire. I don't know how much current will pass through the wire, so I used the largest I could find.

Here's how I tested the bypass. I disconnected the Aux battery at N1 and the ground wire at the Main battery negative terminal to simulate a bad aux battery. The voltmeter confirms the disconnect with low voltage at N1.

Here's a shot of the dead instrument panel due to the disconnected Aux battery.

Here's the jumper installed between N1 and N2, voltmeter shows the Main battery voltage at N1.

Here's the live instrument panel.

Here's the instrument panel after starting, only error indicated is open hood.

For those interested, following are some diagrams to illustrate how I understand it works. (See this thread for additional information on the dual battery system https://www.jlwranglerforums.com/forum/threads/3-6l-ess-battery-diagram.14401/)

Here's the battery voltages on a working system, the PCR is connecting the batteries in parallel, both batteries providing power to everything. Normal operation is verified with 0 volts between N1 and N2.

Here's the effect of a failed Aux battery, no power to critical electronics. This should be verifiable by a voltage difference between N1 and N2.

Bypassing is accomplished by jumping N1 to N2. This diagram illustrates the jumper getting power back to the critical electronics.

(updated 04/13/2019)
Additional 3.6L ESS system information is available here.
3.6L ESS Dual Battery Consolidated Information
https://www.jlwranglerforums.com/forum/threads/3-6l-ess-dual-battery-consolidated-information.2

I've seen quite a few posts related to failed Aux batteries causing flaky or dead electronics, stalling and failing to start/auto restart. I've come up with a simple way to temporarily bypass a bad Aux battery (also blown PCR fuse or bad PCR) and get back on the road. Warning - this post contains a lot of informed assumptions, so post your related experiences to help validate or invalidate any information I've provided.

Here's a picture of my bypass kit. The jumper is used to connect the N1 terminal to the N2 terminal. I wanted to be able to install the jumper securely, but still be able to quickly disconnect it. A fused jumper seemed to be the best and cheapest way to go. Removing the fuse is a simple way to disconnect the jumper and it protects against overloading the wire. I don't know how much current will pass through the wire, so I used the largest I could find.

Here's how I tested the bypass. I disconnected the Aux battery at N1 and the ground wire at the Main battery negative terminal to simulate a bad aux battery. The voltmeter confirms the disconnect with low voltage at N1.

Here's a shot of the dead instrument panel due to the disconnected Aux battery.

Here's the jumper installed between N1 and N2, voltmeter shows the Main battery voltage at N1.

Here's the live instrument panel.

Here's the instrument panel after starting, only error indicated is open hood.

For those interested, following are some diagrams to illustrate how I understand it works. (See this thread for additional information on the dual battery system https://www.jlwranglerforums.com/forum/threads/3-6l-ess-battery-diagram.14401/)

Here's the battery voltages on a working system, the PCR is connecting the batteries in parallel, both batteries providing power to everything. Normal operation is verified with 0 volts between N1 and N2.

Here's the effect of a failed Aux battery, no power to critical electronics. This should be verifiable by a voltage difference between N1 and N2.

Bypassing is accomplished by jumping N1 to N2. This diagram illustrates the jumper getting power back to the critical electronics.

(updated 04/13/2019)
Additional 3.6L ESS system information is available here.
3.6L ESS Dual Battery Consolidated Information
https://www.jlwranglerforums.com/forum/threads/3-6l-ess-dual-battery-consolidated-information.2

If you disconnect the Aux battery ground cable form the Main battery terminal, that should isolate it from the system so it won't run down. The problem is trying to jump start from the Aux battery with a drained Main battery still connected, as that will put additional load on the Aux battery. After you reconnect the Aux battery to the Main battery terminal, removing that terminal from the Main battery would isolate the drained Main battery from the system. After starting, you would have to reconnect the Main battery terminal while running.

In brief, disconnect Aux ground before running accessory. When done, reconnect the Aux ground. If the Main battery was severely drained, disconnect Main battery terminal before attempting a start from the Aux battery.

edited 1/12/19 with updated diagram
In case the other diagrams aren't clear, here's a simplified diagram to emphasize how the batteries are connected in parallel through the PCR. A bad Aux battery seems to cause issues with the Aux battery powered systems, this shows the bypass jumper connecting the Main battery to the Aux battery powered systems.

Just completed two weeks with the Aux battery bypassed. No difference in the operation of the jeep, I actually forgot it was bypassed. Bypassing hasn't changed the running voltage, still running around 14.7 v.

I don't have any plans to physically remove it, but with the ground cable disconnected there is no electricity flowing through it, so it is electrically removed. It does provide a benefit when it works, so as long as I can bypass it when it doesn't, it will stay in unless I install a real dual battery system.

Don't wait until it goes bad to bypass it, if you're going to do it, bypass it while it is still good. Then if your main battery is not able crank the starter, you have a functional backup available.

I am not planning to permanently remove the Aux battery. The fuse in the jumper is to facilitate quickly bypassing/un-bypassing the Aux battery. With the fuse in and the Aux negative disconnected, the Aux battery is bypassed. With the fuse out and the Aux negative connected, the Aux battery is not bypassed.

 

[Jebiruph]

Jerry, Jerry, Jerry - great stuff - thank you!

Like many, I'm on both the JL and JT Gladiator forums (I own the latter). I can easily assume the JT is no different than the JL in regard to the two batteries. BUT rather than assume, does anyone know for sure so I can follow everything in this great thread knowing it applies to my JEEP?

Also, I can't afford to spend big bucks on a Genesis kit so I'll be considering a 2nd battery in the bed of my Gladiator. I'll need to find and understand info on if/how a dual battery setup changes due to the AUX/ESS battery.

Thanks again, -Dan

I have to believe the JT has the same battery setup as the JL (and Pacifica, Durango and Grand Cherokee). You can test by removing the positive terminal from the main battery (being careful not to let it short to ground) and verifying the JT still starts. Or you could verify the existence of the PCR behind the passenger side front wheel fender liner.

The Genesis kit https://www.jlwranglerforums.com/forum/threads/genesis-off-road-dual-battery-kit.5422/ replaces the Aux/Main batteries with a battery pair that for ESS purposes acts like a single battery. The Genesis battery pair does not split and power separate systems during an auto stop like the Aux and Main do.

 

[Jebiruph]

For my benefit and hopefully others, I've re-quoted a number of what I think are key posts to put them in one place as this thread is, at 11+ pages, quite informative and long...

If you haven't seen it yet, I use this thread https://www.jlwranglerforums.com/forum/threads/3-6l-ess-dual-battery-consolidated-information.25377/ to provide the highlights of my battery related threads.

 

[WhatExit?]

I have to believe the JT has the same battery setup as the JL (and Pacifica, Durango and Grand Cherokee). You can test by removing the positive terminal from the main battery (being careful not to let it short to ground) and verifying the JT still starts. Or you could verify the existence of the PCR behind the passenger side front wheel fender liner.

The Genesis kit https://www.jlwranglerforums.com/forum/threads/genesis-off-road-dual-battery-kit.5422/ replaces the Aux/Main batteries with a battery pair that for ESS purposes acts like a single battery. The Genesis battery pair does not split and power separate systems during an auto stop like the Aux and Main do.

Sounds like a big benefit to going with the Genesis dual battery kit. If only it wasn't so so costly

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