Jumperless Aux Battery Bypass

[Leisure Freak]

Been planning on doing the jumperless bypass for a while. I was gone for 10 days while the Jeep was on a battery tender. When I returned, I noticed my tender light was red. Checked Jeep. Batteries completely dead.
I did the bypass ,"Pulled aux neg, remove fuse F42". I was able to charge the main and run the jeep but the main was toast too. I charged it then let it sit overnight and the voltage was down to 12.2 the next morning.

I bought an AGM H7 battery and all is well. I do not have an ESS bypass nor after reading through most of this thread again do I see the real need for an ESS bypass. I've got a 850 CCA battery cranking a 4-cylinder engine on ESS every once and awhile.
Can someone give me a technical answer for why I actually need a ESS bypass?
The only reasons for a bypass that I have seen so far it would be possible to deplete the main battery with ESS activated. That doesn't make sense to me.

My F150 truck had a slightly bigger battery and ESS is active all the time unless I get into a town with lots of red lights. I get aggravated and then disable it. I never have a problem with it running the battery down.

I did as you did, running off of the new main battery with neg aux cable removed along with the F42 fuse pulled. No issues and no ESS bypass added. Generally a few ESS active events would probably go without issue. The prob is triggering ESS and the main battery alone is unable to meet the needs and restart. I know it is not a technical explanation but is the reason I've always pushed the stupid button ater start to disable ESS. Never have had a hiccup. If pushing the disable ESS button was ever too big a shore for me I would just pull the outer hood pin and live with it and its resulting dash light display that way. But that's just me. I bought a sport with crank windows/manual locks just to have the least amount of electronics and tech that I could. After over 35 years as a tech engineer, I've seen and had enough.

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[Down South]

I did as you did, running off of the new main battery with neg aux cable removed along with the F42 fuse pulled. No issues and no ESS bypass added. Generally a few ESS active events would probably go without issue. The prob is triggering ESS and the main battery alone is unable to meet the needs and restart. I know it is not a technical explanation but is the reason I've always pushed the stupid button ater start to disable ESS. Never have had a hiccup. If pushing the disable ESS button was ever too big a shore for me I would just pull the outer hood pin and live with it and its resulting dash light display that way. But that's just me. I bought a sport with crank windows/manual locks just to have the least amount of electronics and tech that I could. After over 35 years as a tech engineer, I've seen and had enough.

Thanks for the reply.
Pushing the ESS bypass button is no problem for me either. If I forget, the first time the ESS activated, I would press the button and bypass it.
My problem is the wife. She is technically challenged. She doesn't drive the Jeep that often and I will have to go over what button to press and when every time she drives the Jeep.
I may purchase the start/stop bypass somewhere down the road. I have no use for a Tazer.

 

[GtX]

My problem is the wife.

Almost always is.

 

[Heimkehr]

Can someone give me a technical answer for why I actually need a ESS bypass?

The only thing that comes to mind in that regard is the potential increase in the battery(s) practical service life. Really, the prevailing reason for disabling ESS is just one of convenience; in other words, not having to remember to press the dash button every time.

My problem is the wife.

My Missus is a decent, safe driver. My only quibble, and it's not an insignificant one, is that she inherited her mother's habit of occasionally parking by contact. And so I purchased a $10 Stop-sign-on-a-stick as a gentle reminder to not have any more expensive bumps. ?

 

[ConqSoft]

The only thing that comes to mind in that regard is the potential increase in the battery(s) practical service life. Really, the prevailing reason for disabling ESS is just one of convenience; in other words, not having to remember to press the dash button every time.



My Missus is a decent, safe driver. My only quibble, and it's not an insignificant one, is that she inherited her mother's habit of occasionally parking by contact. And so I purchased a $10 Stop-sign-on-a-stick as a gentle reminder to not have any more expensive bumps. ?

Ha, same. Even though she has a BMW with all the fancy sensors and 360 cameras I still have one of these in place:

https://www.amazon.com/Zone-Large-H...d2lkZ2V0TmFtZT1zcF9zZWFyY2hfdGhlbWF0aWM&psc=1

 

[DonH63]

Ha, same. Even though she has a BMW with all the fancy sensors and 360 cameras I still have one of these in place:

https://www.amazon.com/Zone-Large-Heavy-Rubber-Parking/dp/B085P221F5/ref=sxin_18_pa_sp_search_thematic_sspa?content-id=amzn1.sym.749943ff-94bd-4679-8f03-3b5488f65fae:amzn1.sym.749943ff-94bd-4679-8f03-3b5488f65fae&crid=2ZIEGYF0MFLT1&cv_ct_cx=garage+parking+stopper&keywords=garage+parking+stopper&pd_rd_i=B085P221F5&pd_rd_r=b5821b6b-57a0-4576-a9c8-8ac75541ae65&pd_rd_w=h1o1A&pd_rd_wg=uYqkv&pf_rd_p=749943ff-94bd-4679-8f03-3b5488f65fae&pf_rd_r=P5PE6SM1SFQ1M7KW4VSJ&qid=1688564951&sbo=RZvfv//HxDF+O5021pAnSA==&sprefix=garage+parking+stopper,aps,101&sr=1-1-2b34d040-5c83-4b7f-ba01-15975dfb8828-spons&ufe=app_do:amzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840&sp_csd=d2lkZ2V0TmFtZT1zcF9zZWFyY2hfdGhlbWF0aWM&psc=1

I've been thinking about these for a while, thanks for the link! My wife bumped her Suburban into my tool chest, which bent a drawer but did more damage to the sub, and I managed to nudge a shelf with my Grand Cherokee (moved the shelf out a little to get behind and forgot to put it back, duh!)

I put it in my cart, but am now stuck deciding if the 2 or 3 year extended warranty is a better deal? (The extended warranty marketing is sooo out of control.)

 

[Go Hogs!]

I still have 22 months of warranty left, and I have been hesitant to bypass the auxiliary battery for that reason. If I did the bypass but then needed to reattach the now dead aux battery before going in to the dealership for a warranty issue, how long would it take the aux to take out the main battery? Would I be able to drive the 25 miles to the dealership with a dead aux reconnected? I know I could periodically charge the aux to keep it on life support but was curious what would happen if it wasn’t charged. Thanks very much.

 

[OldGuyNewJeep]

I still have 22 months of warranty left, and I have been hesitant to bypass the auxiliary battery for that reason. If I did the bypass but then needed to reattach the now dead aux battery before going in to the dealership for a warranty issue, how long would it take the aux to take out the main battery? Would I be able to drive the 25 miles to the dealership with a dead aux reconnected? I know I could periodically charge the aux to keep it on life support but was curious what would happen if it wasn’t charged. Thanks very much.

Charge it before disconnecting. Unless it has a bad cell it should be shelf stable for years. Think about how long they sit on store shelves…

 

[Leisure Freak]

I still have 22 months of warranty left, and I have been hesitant to bypass the auxiliary battery for that reason. If I did the bypass but then needed to reattach the now dead aux battery before going in to the dealership for a warranty issue, how long would it take the aux to take out the main battery? Would I be able to drive the 25 miles to the dealership with a dead aux reconnected? I know I could periodically charge the aux to keep it on life support but was curious what would happen if it wasn’t charged. Thanks very much.

I did the bypass while the Aux battery was still functional. I keep my Aux available for emergency use or for if/when I may need to to add it back to the system. Even though it isn't being used for anything I put the trickle charger on it every 3 weeks and it does take a couple of hours or more to recharge 100%. So it does discharge slowly while in this state of disconnect.

 

[Ben-Zair Dun-Zatt]

Good day friends, I have been following the forum and posts for many years. You all are full of good advice and money saving tips. This last tip about making a duel battery set up to a single battery will save me thousands of dollars over the life of the Jeep.
I wanted to thank all of you.
However, some one posted that they showed concern about putting the negative cable on a smaller post when the single mod is performed. This also sparked a concern of mine because I view it a possible current/amp reduction To the battery.
So I put on the empty battery post with the original nut and a 24 inch battery cable with stud holes on both ends. I bought the battery cable at advance auto for $13 and I had to also buy some metric nuts M8-1.25 hex nuts for $4. I did not have the metric nuts to use. I put the nut on an empty ground stud on the fender wall attached to the same grounding buss bar. Real easy to do.
If it’s not needed, that is good, if helps or not, it’s there now.
I am attaching images for you.
Again all, thanks for your advice through the years.

 

[Sajeep]

I just did the above but I’m still getting the red notice on my dash. Will it go away eventually or I’m I doing something wrong ?

 

[Ben-Zair Dun-Zatt]

Sajeep, did you Pull fuse F42 in fuse panel FIRST, remove aux neg battery cable at main battery and tape the cable terminal with insulation tape? Be sure the negative (black) cable you remove at the main battery is from the aux batter below the fuse box. Two negative black battery cables end at the negative battery terminal. If you trace the negative battery cable back to the engine compartment right fender negative buss in my picture, THIS CABLE IS CONNECTED TO THE STUD THAT HAS THE PCR ON IT.
To simpify basically all you are doing is:
1. pulling fuse F42 in fuse box
2. removing aux battery cable terminal from main battery neg post that is connected to PCR
3. removing other negative battery neg terminal and reconnected it to PCR neg battery post
I read in one of the previous posts something about a mod on the earlier jeeps had something to do with being able to do this. Since I had a 2020, I did not read it throughly because it did not pertain to mine.
What I posted pertained to adding an addition negative cable because someone posted (and I agreed with) the negative cable being removed was larger than the smaller one remaining on it. So I was concerned with current carrying issues. But many people posted they had no problem.
If nothing else works, I would pull both negative and positive battery terminals and try to clear a possible fault. Just my opinion. Of course you would need to reset you clock, radio and other things.
I truly believe it is worth the time, effort and money to find out why it’s throwing a light. It will save you a lot of money and frustration in the future. I did exactly what the poster said to do and it worked for me.
Maybe some of the guys may have some additional advice for you. Good luck, please keep us posted.?

 

[Sajeep]

I didn’t pull the fuse first. I did it after removing the negative connection . Would that make a difference ? I also think my house battery is toast .

 

[jludave]

Would that make a difference ?

Yes. Pulling the fuse is what disables PCR, which is what controls ESS.

And, all you need to do is disconnect what should be the thinner of the 2 negative battery cables. Wrap the end with electrical or Tesa tape and zip tie out of the way.

 

[Ben-Zair Dun-Zatt]

Sajeep, if F42 controls a latching relay, the answer would be yes, it would make a difference pulling the fuse first. I am not sure what relay or electronics it controls, but if in fact it does make a difference if it controls a latching relay.
What do you mean by “house battery “? Is house battery the main battery or aux battery that is “Toast”?

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