3.6L ESS Aux Battery Bypass

OP
Jebiruph

Jebiruph

Well-Known Member
First Name
Jerry
Joined
Feb 18, 2018
Messages
1,304
Reaction score
1,573
Location
Iowa
Vehicle(s)
2018 JLU, 2019 KL, 2020 JT
  • Thread starter
  • Thread Starter
  • #226
A while back one of the you tubers I watch, Kevin and Britney with Lite Brite, showed a way to jump the jeep using a jumper wire. Was this related to possibly a bad aux and then using the bypass that has been stated in this thread? Or did he do something else to “jump” the jeep? Just trying to make sure I understand. I plan to build a jumper wire as well per the instructions in this thread as I don’t want to be stranded while camping or off roading.

I did a search and can’t for the life of me find the episode where Kevin does this, maybe someone on here has a link to it but either way. Would like to know what he did so I don’t end up stranded.
I saw that, they were demonstrating that if the aux battery fails, but the main battery is good, the jumper gets you past the cold start aux battery test. They later replaced the temporary jumper with a permanent unfused jumper, I would only recommend a fused jumper unless the aux battery is removed.





Advertisement

 

MadDog27

Well-Known Member
First Name
Jon
Joined
Mar 5, 2019
Messages
651
Reaction score
1,058
Location
Aurora, Colorado
Vehicle(s)
2021 JLUR 2.0T, 2019 Subaru Ascent
Vehicle Showcase
1
I saw that, they were demonstrating that if the aux battery fails, but the main battery is good, the jumper gets you past the cold start aux battery test. They later replaced the temporary jumper with a permanent unfused jumper, I would only recommend a fused jumper unless the aux battery is removed.
Perfect! Thank you for the help and all the work you’ve put into this thread.
 

cbrenthus

Well-Known Member
Joined
May 2, 2018
Messages
692
Reaction score
792
Location
FL
Vehicle(s)
'19 Mojito JLUR
I see. So the point of eliminating the AUX Battery is what then ?
Because it is harder to jump if it dies or cause it is acting parasitic on the MAIN Battery ?
I've read a lot of Aux battery failures, and when it goes it takes the main with it. I don't want to have to worry about 2 batteries in parallel, especially when I don't use ESS. ;)
 

c2m2h3

Well-Known Member
First Name
Chris
Joined
May 13, 2017
Messages
246
Reaction score
58
Location
US
Vehicle(s)
2012 JKU Wrangler Sahara
I TOTALLY Agree....

So the Jumper BYPASSES the Aux ? and uses the Main for the Cold Start Aux Test and everything else ? Basically taking the 2 Batteries OUT of Parrell ?

Chris
 
OP
Jebiruph

Jebiruph

Well-Known Member
First Name
Jerry
Joined
Feb 18, 2018
Messages
1,304
Reaction score
1,573
Location
Iowa
Vehicle(s)
2018 JLU, 2019 KL, 2020 JT
  • Thread starter
  • Thread Starter
  • #230
I TOTALLY Agree....

So the Jumper BYPASSES the Aux ? and uses the Main for the Cold Start Aux Test and everything else ? Basically taking the 2 Batteries OUT of Parrell ?

Chris
The ESS system has main battery circuits and aux battery circuits that are connected by the PCR (Power Control Relay) except when auto stopped and during a brief cold start test. All the jumper does is keep the main battery circuits and aux battery circuits connected, regardless of what the PCR is doing. Virtually the same thing is accomplished by unplugging the PCR, since it can't separate the circuits when it is unplugged. This allows you to run on either or both batteries. All system modifications are at your own risk.
 

c2m2h3

Well-Known Member
First Name
Chris
Joined
May 13, 2017
Messages
246
Reaction score
58
Location
US
Vehicle(s)
2012 JKU Wrangler Sahara
I thought that the goal was to prevent the Aux from Draining the Main.....This sounds like they are specifically tied together with the Jumper.....How does the Jumper help that situation ?
 
OP
Jebiruph

Jebiruph

Well-Known Member
First Name
Jerry
Joined
Feb 18, 2018
Messages
1,304
Reaction score
1,573
Location
Iowa
Vehicle(s)
2018 JLU, 2019 KL, 2020 JT
  • Thread starter
  • Thread Starter
  • #232
I thought that the goal was to prevent the Aux from Draining the Main.....This sounds like they are specifically tied together with the Jumper.....How does the Jumper help that situation ?
Since you can run on either or both batteries, you can disconnect either battery you want at your own risk.
 

c2m2h3

Well-Known Member
First Name
Chris
Joined
May 13, 2017
Messages
246
Reaction score
58
Location
US
Vehicle(s)
2012 JKU Wrangler Sahara
So connect both with the Jumper, and then you can disconnect the AUX (Negative lead ?) and it doesn't cause a drain to the Main Battery ? (At your own risk, of course)
 
OP
Jebiruph

Jebiruph

Well-Known Member
First Name
Jerry
Joined
Feb 18, 2018
Messages
1,304
Reaction score
1,573
Location
Iowa
Vehicle(s)
2018 JLU, 2019 KL, 2020 JT
  • Thread starter
  • Thread Starter
  • #234
So connect both with the Jumper, and then you can disconnect the AUX (Negative lead ?) and it doesn't cause a drain to the Main Battery ? (At your own risk, of course)
That's correct, a disconnected aux battery will not drain the main battery and the negative lead seems to be the obvious way to disconnect it.
 

c2m2h3

Well-Known Member
First Name
Chris
Joined
May 13, 2017
Messages
246
Reaction score
58
Location
US
Vehicle(s)
2012 JKU Wrangler Sahara
Thanks again, again, again and I'm sure several more times, Jerry

Makes sense....
 

Rufus

Well-Known Member
Joined
Jun 2, 2019
Messages
692
Reaction score
571
Location
NYC
Vehicle(s)
2018 2 door JL Sport 3.6 V6
That's correct, a disconnected aux battery will not drain the main battery and the negative lead seems to be the obvious way to disconnect it.
But just to accomplish the bypass you only need the jumper, correct? I just want to have it for the situation when the aux battery dies.
 
Last edited:

c2m2h3

Well-Known Member
First Name
Chris
Joined
May 13, 2017
Messages
246
Reaction score
58
Location
US
Vehicle(s)
2012 JKU Wrangler Sahara
I believe that the Jumper is also necessary if you should need to jump the vehicle with something like a jump pack.....There has been info posted about how to connect the Jumper, and what to disconnect from the batteries when jumping the JL. I can't fully explain it, but I know I have the info saved somewhere....
 

Rufus

Well-Known Member
Joined
Jun 2, 2019
Messages
692
Reaction score
571
Location
NYC
Vehicle(s)
2018 2 door JL Sport 3.6 V6
I believe that the Jumper is also necessary if you should need to jump the vehicle with something like a jump pack.....There has been info posted about how to connect the Jumper, and what to disconnect from the batteries when jumping the JL. I can't fully explain it, but I know I have the info saved somewhere....
I will go back through this thread but my understanding was that the jumper would solve the problem of the main battery being able to trigger the relay to allow it to crank the starter (as opposed to the aux battery having to trigger the relay).
 

c2m2h3

Well-Known Member
First Name
Chris
Joined
May 13, 2017
Messages
246
Reaction score
58
Location
US
Vehicle(s)
2012 JKU Wrangler Sahara
I'll let the pros answer that....it "sounds correct"......
 

Advertisement




Morris 4x4 Center
 



Advertisement
Top