Jumperless Aux Battery Bypass

[WranglerDad]

Yup. I’ve been wavering back and forth. By “leaving them in place” and “making sure it doesn’t short out” I assume u mean to disconnect both pos and negative. I though some had said to leave positive on the old Aux batt or connect it to main. Did u just tape yours off?

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[mdkautzman]

Does anyone ever hook the aux battery back up to charge it once in a while incase you need to revert back for a dealer visit?
Seems if you need to go in for a service and want it all factory again the aux battery will just drain your main due to sitting so long uncharged. Possibly now a bad aux battery after a while without constant charging.

 

[OldBlue]

Does anyone ever hook the aux battery back up to charge it once in a while incase you need to revert back for a dealer visit?
Seems if you need to go in for a service and want it all factory again the aux battery will just drain your main due to sitting so long uncharged. Possibly now a bad aux battery after a while without constant charging.

Once every couple of months I set up a trickle charger on the aux battery just to keep them topped up just for dealer visits. Since the wife's '20 JLUSS is almost out of warranty (mileage) I'll just the aux in hers die.

 

[Stuckinthesand]

Yup. I’ve been wavering back and forth. By “leaving them in place” and “making sure it doesn’t short out” I assume u mean to disconnect both pos and negative. I though some had said to leave positive on the old Aux batt or connect it to main. Did u just tape yours off?

Just disconnect the negative if you leave the aux battery in place. If you remove the aux you need to run it to the main. Tape off the negative.

 

[bud1lite]

Taser mini is installed and operates awesome I’m baffled…. After both grounds were secured I started the jeep and drove it without the fuse in and no dash light either, Im totally at a loss for words I followed everyones directions as if it weren’t easy enough but testing my battery out of the jeep was just an added bonus to help figure out what is going on.

So yours is a 20 model?My 22 is probably the same then....ohno

 

[rhocking]

I debated on whether to start a new thread or post in this thread where there is already a lot of good information in regards to the 'easy' way to do an Aux battery bypass.

Decided to ask the questions here so that anyone searching this thread would find the answer.

Q1: When doing a jump start, for example using a battery pack, with the fuse 42 out and Aux battery Negative disconnected is the battery pack connected to Main Positive terminal and Main battery Negative terminal?
and
Q2: With both batteries in play I have read that a more powerful battery pack/jump starter is required. Is this still true with the Aux battery bypassed or does the system behave as though the Jeep is 'normal' and has a single battery?

 

[GrayWolf.Overland]

I debated on whether to start a new thread or post in this thread where there is already a lot of good information in regards to the 'easy' way to do an Aux battery bypass.

Decided to ask the questions here so that anyone searching this thread would find the answer.

Q1: When doing a jump start, for example using a battery pack, with the fuse 42 out and Aux battery Negative disconnected is the battery pack connected to Main Positive terminal and Main battery Negative terminal?
and
Q2: With both batteries in play I have read that a more powerful battery pack/jump starter is required. Is this still true with the Aux battery bypassed or does the system behave as though the Jeep is 'normal' and has a single battery?

With the fuse gone, the main battery is the sole cranking battery and for jump start purposes you should consider this setup like it's a single battery vehicle.

My understanding on this is not as thorough as @Jebiruph , but IMO
the Aux positive is connected to the main positive just to keep some systems happy and allow the jeep to operate thinking there is AUX connected and in parallel

 

[Canucklesammich]

Hey miketomp1972, did you buy your 2020 new or used? If you got it used, who knows what any previous owner did trying to wire up lights, a winch or something else. If you got it new, then you got me...maybe a worn, frayed main wire that doesn't provide a proper ground & needs the aux wire to ground properly. Just guessin'.

 

[Canucklesammich]

With the fuse gone, the main battery is the sole cranking battery and for jump start purposes you should consider this setup like it's a single battery vehicle.

My understanding on this is not as thorough as @Jebiruph , but IMO
the Aux positive is connected to the main positive just to keep some systems happy and allow the jeep to operate thinking there is AUX connected and in parallel

Yup, you're correct. Another reason to leave the hot side still connected to the aux with the ground disconnected is that power is still flowing in through the red cable( though there's no current) and if it hits something grounded, like the side of the engine bay it will at least start blowing fuses, possibly a lot worse (then you WILL have current flow ). This is also why the aux won't recharge after the ground disconnect and if not maintained w/ a charger from time to time, it'll eventually just go dead.

 

[Stuckinthesand]

I debated on whether to start a new thread or post in this thread where there is already a lot of good information in regards to the 'easy' way to do an Aux battery bypass.

Decided to ask the questions here so that anyone searching this thread would find the answer.

Q1: When doing a jump start, for example using a battery pack, with the fuse 42 out and Aux battery Negative disconnected is the battery pack connected to Main Positive terminal and Main battery Negative terminal?
and
Q2: With both batteries in play I have read that a more powerful battery pack/jump starter is required. Is this still true with the Aux battery bypassed or does the system behave as though the Jeep is 'normal' and has a single battery?

With fuse pulled and aux negative disconnected you should have no issue using a jump pack and I can confirm did use a jump pack in my situation with no issues. If both batteries were still connected it would be very hard to get it started off a jump pack.

 

[Tiger4Life]

Ok I have read so many threads and I’m all confused. I have removed fuse F42. Aux battery is still in place. So I need to remove the neg battery cable from the main? I’ve been fighting this for over a month. If someone has time I’ll give my cell and you can let me know which cable to remove from the neg side from the main

 

[Rhinebeck01]

Ok I have read so many threads and I’m all confused. I have removed fuse F42. Aux battery is still in place. So I need to remove the neg battery cable from the main? I’ve been fighting this for over a month. If someone has time I’ll give my cell and you can let me know which cable to remove from the neg side from the main

@Tiger4Life

PM sent.

 

[Tiger4Life]

@Rhinebeck01 has been a life saver for me and a wealth of knowledge. I am now a lot smart than I was this morning. Any of you guys on here need to take his advice. Thx so much for all the help

Mike

 

[miketomp1972]

Update to my dilemma, may main battery tested at home @ 12.7

As long as the ground is disconnected and fuse pulled it bypasses the aux. The PCR is what makes the batteries work together by having them connected in parallel. By pulling the fuse and removing the negative terminal you are taking the aux out of the equation. Just like the main battery without a negative you don’t have power to anything. Now if you didn’t pull the fuse and only disconnected the negative terminal you would get the error symbol on your EVIC. By pulling the fuse you are stopping the system from doing a self test on the aux battery. This is why it is still necessary to deactivate start/stop even with the aux disconnected. You can never truly delete the aux setup. It would just use the main battery in a start/stop situation if not deactivated.
[/QUO
Update: thank you stuckinsand my voltage was 12.7 at home, AutoZone said battery reset good and having faith in them I continued my attempt with this bypass which brought me to this thread and with your suggestion I had a friend test my battery this time on his meter and the battery said BAD. Went to AutoZone again and it came back as bad….. pissed sooo bought a new AGM the larger one went home and guess what yup now everything works as you described. thank you

 

[bud1lite]

Nice!Thanks for the update!

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