Jumperless Aux Battery Bypass

[ResqFE]

So I disconnect the aux battery and pulled the F42 fuse. I still get the cuation light on dash.
Comments or recommemdations?

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[Rhinebeck01]

I have an 2018 JLU Sahara, manufacture date 1/18. I got the “start/stop in battery protect mode” message the other day. I did some poking around and discovered my main battery was around 11.5 volts and my aux was around 12.5 volts. I disconnected the aux. battery negative from the main battery and the Jeep wouldn’t start, main battery was too weak. I reconnected the aux negative and it started back up. Long story short, my aux battery is what was giving the Jeep the extra power to start. My aux battery was replaced by Jeep about 2 years ago while still under warranty and the main was original. I put a battery tester on them and the main tested bad and the aux was still good.
I also noticed the voltage meter on the Jeep was constantly around 14.1 volts when the Jeep was running. I guess it was trying to always charge my bad main battery.
I bought a new main battery and installed with the aux still connected. Now when I first start driving it is around 14 volts. As it charges, the voltage will vary from 12.8 to 14.1 volts, as I believe it is designed to do. At first it starts around 14.1 and gets lower and lower the longer you drive, and it charges, eventually getting to 12.8 volts. When you take your foot off the gas the voltage goes up, charging more when you aren’t using engine power. When you push the gas pedal down the voltage drops down. This is a gas saving measure Implemented on new cars. It usually takes 40-60 minutes of driving before mine gets as low as 12.8, which to me indicates batteries are fully charged.

I also have just decided to install the $50 auto stop/start disable from Amazon.
FURYENGRAVER Plug Play Engine... https://www.amazon.com/dp/B08YN5S713?ref=ppx_pop_mob_ap_share
It was easy to install and seems to work with no problems. It automatically disables auto start/stop every time you start the Jeep. If you push the start stop button, it will still work, Basically it makes the Jeep default to auto stop/start disabled, which is what I like.

After two days of the auto stop/start working with no issues, I decided to try the F42 fuse removal along with disconnecting the aux battery negative cable from the main battery. Everything is working perfectly. No error codes, no having to push the auto start/stop button every time I start the Jeep, no aux battery issues to worry about.

??

@JL18

I'm not familiar with that offering .... the FURYENGRAVER Plug Play Engine Auto Start Stop Eliminator Cable for 2018-2021 Jeep Wrangler JL JLU....

It uses the OBDll port as part of the install, no way would I have installed that unit...

I suggest you return that iffy offering to Amazon for a refund now, while you can... Now, before you have battery(s) related issues thanks to that offering.

It is highly likely that that unit, will intermittently wake up UConnect and cause battery depletion..
.. Also, there is a big concern that the unit's parasitic draw will deplete battery(s).

Were I you, I would have purchased a SmartStopStart unit.

Yes, the SmartStopStart unit will cost you $100, but that unit has proven to be a no problem ... never hiccuping unit, to use with the JL or JT. Many use the SmartStopStart.

.

 

[Rhinebeck01]

So I disconnect the aux battery and pulled the F42 fuse. I still get the cuation light on dash.
Comments or recommemdations?

@ResqFE

Viewing your post on smartphone... hard to tell but did you disconnect the smaller of the 2 cables on your Main battery Neg side.. The smaller of the two cables is the Aux negative.

 

[ResqFE]

Yep... smaller one. Still habe light and 14+ volts on dash

 

[ResqFE]

I have had a tazer installed for 6 months, no issues

 

[NewJLU2019]

@JL18

I'm not familiar with that offering .... the FURYENGRAVER Plug Play Engine Auto Start Stop Eliminator Cable for 2018-2021 Jeep Wrangler JL JLU....

It uses the OBDll port as part of the install, no way would I have installed that unit...

I suggest you return that iffy offering to Amazon for a refund now, while you can... Now, before you have battery(s) related issues thanks to that offering.

It is highly likely that that unit, will intermittently wake up UConnect and cause battery depletion..
.. Also, there is a big concern that the unit's parasitic draw will deplete battery(s).

Were I you, I would have purchased a SmartStopStart unit.

Yes, the SmartStopStart unit will cost you $100, but that unit has proven to be a no problem ... never hiccuping unit, to use with the JL or JT. Many use the SmartStopStart.

.

This does the same thing the Tazer will do. Question if the Aux battery is never being ran will it end up same issues ??

Our SmartStopStart product is a memory device for the ESS disable button. It retains factory operation of ESS disable button, but allows the vehicle to remember your preference for each time you start the Jeep, rather than always defaulting to ESS ON as it does from the factory.

 

[Rhinebeck01]

This does the same thing the Tazer will do. Question if the Aux battery is never being ran will it end up same issues ??

Our SmartStopStart product is a memory device for the ESS disable button. It retains factory operation of ESS disable button, but allows the vehicle to remember your preference for each time you start the Jeep, rather than always defaulting to ESS ON as it does from the factory.

Neither the current offering, Tazer JL Mini or the SmartStopStart unit use the OBDll port.

The FURYENGRAVER Plug Play Engine Auto Start Stop Eliminator Cable for 2018-2021 Jeep Wrangler JL JLU uses the OBDll port which is not good.... can lead to major issues ...

As for your ? .....

A JL that has the owner doing the ESS button push or has a unit, in essence, do the ESS button push.... is the JL, any less apt to have fewer or no Aux battery issues.. The answer is no.

.

 

[JL18]

@JL18

I'm not familiar with that offering .... the FURYENGRAVER Plug Play Engine Auto Start Stop Eliminator Cable for 2018-2021 Jeep Wrangler JL JLU....

It uses the OBDll port as part of the install, no way would I have installed that unit...

I suggest you return that iffy offering to Amazon for a refund now, while you can... Now, before you have battery(s) related issues thanks to that offering.

It is highly likely that that unit, will intermittently wake up UConnect and cause battery depletion..
.. Also, there is a big concern that the unit's parasitic draw will deplete battery(s).

Were I you, I would have purchased a SmartStopStart unit.

Yes, the SmartStopStart unit will cost you $100, but that unit has proven to be a no problem ... never hiccuping unit, to use with the JL or JT. Many use the SmartStopStart.

.

It does not plug into your OBDII port. Your OBDII port is left with nothing plugged into it. So far it’s been perfect. Not a glitch and I haven’t noticed any parasitic draw issues, but I drive it everyday, so I guess I won’t notice till it sits a long time without being driven.
Here is a YouTube video I found showing it’s installation. I’ll buy the tried in true if I have to but I’ll try to save $50 first?

 

[Rhinebeck01]

@JL18

I did some internet searching in regard to this device after my post here.... and did find info that says no OBDll port usage which is a positive thing. The ad for that device made it seem like the OBDll port was used which would be bad..

I did however, find multiple internet posts that did mention that the device you installed does in fact hiccup intermittently though.. other similar knock off offerings also hiccup intermittently.

The only unit that never hiccups is the SmartStopStart unit that most here have installed. I know I will only recommend the SmartStopStart unit.

Note: Resale value of a used SmartStopStart unit is very good.... just the opposite of that for the iffy, hiccuping Chinese knock offs.

 

[JL18]

@JL18

I did some internet searching in regard to this device after my post here.... and did find info that says no OBDll port usage which is a positive thing. The ad for that device made it seem like the OBDll port was used which would be bad..

I did however, find multiple internet posts that did mention that the device you installed does in fact hiccup intermittently though.. other similar knock off offerings also hiccup intermittently.

The only unit that never hiccups is the SmartStopStart unit that most here have installed. I know I will only recommend the SmartStopStart unit.

Note: Resale value of a used SmartStopStart unit is very good.... just the opposite of that for the iffy, hiccuping knock offs.

Thanks for the info. If I have any weird issues, I’ll pull it out without hesitation and get the $100 one. But, so far it’s been good. Every time I start the Jeep is defaults to start/stop disabled. My remote start works fine. Zero issues, but I’ll be monitoring it closely! Thanks

 

[dazar]

Thanks for sharing all of this information. Since there have been several different experiences with the 2018s, I thought I would share my experience and ask a couple of questions. I have a 2018 JLUR. It is an early 2018 build - I took delivery in May 2018, but I think it was built in Feb or Mar. It is not our daily driver and only has 20k miles on it. I have been getting a message, something like "auto start disabled battery charging" for a little while. Then the other day I went out and it would not start. I assumed it just needed a new battery until I found this forum and realized it also has an Aux battery. Being curious, I removed the F42 fuse and the negative cable to bypass the Aux battery and it started right up. I do not have any warning lights and everything seems fine. I haven't put the top/doors back on yet and it is cold and raining here in Michigan, so I wasn't able to take it for a test drive. I did start it in the garage a few times throughout the day today and everything seems fine. The battery gauge is reading between 14.3 and 14.5. Is it possible my Aux battery is bad, but my main battery is still good? Would a bad Aux battery keep it from starting? From what I've read in this thread, it seems ok to leave the Aux battery where it is while being bypassed -- is it really ok to leave the dead aux battery bypassed and in place indefinitely? Please let me know your thoughts. Thanks!!

 

[Rhinebeck01]

Thanks for sharing all of this information. Since there have been several different experiences with the 2018s, I thought I would share my experience and ask a couple of questions. I have a 2018 JLUR. It is an early 2018 build - I took delivery in May 2018, but I think it was built in Feb or Mar. It is not our daily driver and only has 20k miles on it. I have been getting a message, something like "auto start disabled battery charging" for a little while. Then the other day I went out and it would not start. I assumed it just needed a new battery until I found this forum and realized it also has an Aux battery. Being curious, I removed the F42 fuse and the negative cable to bypass the Aux battery and it started right up. I do not have any warning lights and everything seems fine. I haven't put the top/doors back on yet and it is cold and raining here in Michigan, so I wasn't able to take it for a test drive. I did start it in the garage a few times throughout the day today and everything seems fine. The battery gauge is reading between 14.3 and 14.5. Is it possible my Aux battery is bad, but my main battery is still good? Would a bad Aux battery keep it from starting? From what I've read in this thread, it seems ok to leave the Aux battery where it is while being bypassed -- is it really ok to leave the dead aux battery bypassed and in place indefinitely? Please let me know your thoughts. Thanks!!

@dazar

As you noted, your 2018 JL, built in early 2018 will not start or even try to start, if the Aux battery is depleted.... even though the Main battery is fully charged/healthy, it will not try to start. Forum search using the words TSB 18-092-19 completed (Power Control Update) to learn more about this.

.I strongly suggest that you ASAP, replace your factory installed (in 2018) Main battery.... and yes, keep your dead Aux battery bypassed as you have done.

The Aux battery can be left bypassed forever should you want to do so. Just be sure to limit the use of ESS. Push the ESS button and then drive or buy an adjunct that in essence does that battery push for you.

Read here in regard to the H7 ... again H7 Main battery you will want to buy to replace your current Main battery.. https://www.jlwranglerforums.com/forum/threads/??-main-battery-replacement-talk-jl-jt.100534/

Should you decide to change out the Aux battery read here: https://www.jlwranglerforums.com/fo...ent-the-easy-way-pull-the-fender-flare.56807/

 

[JL18]

Thanks for sharing all of this information. Since there have been several different experiences with the 2018s, I thought I would share my experience and ask a couple of questions. I have a 2018 JLUR. It is an early 2018 build - I took delivery in May 2018, but I think it was built in Feb or Mar. It is not our daily driver and only has 20k miles on it. I have been getting a message, something like "auto start disabled battery charging" for a little while. Then the other day I went out and it would not start. I assumed it just needed a new battery until I found this forum and realized it also has an Aux battery. Being curious, I removed the F42 fuse and the negative cable to bypass the Aux battery and it started right up. I do not have any warning lights and everything seems fine. I haven't put the top/doors back on yet and it is cold and raining here in Michigan, so I wasn't able to take it for a test drive. I did start it in the garage a few times throughout the day today and everything seems fine. The battery gauge is reading between 14.3 and 14.5. Is it possible my Aux battery is bad, but my main battery is still good? Would a bad Aux battery keep it from starting? From what I've read in this thread, it seems ok to leave the Aux battery where it is while being bypassed -- is it really ok to leave the dead aux battery bypassed and in place indefinitely? Please let me know your thoughts. Thanks!!

My Aux battery died about 2 yrs ago and the dealership replaced it under warranty. They didn't say anything about issues with the main battery. After only a few months of the replacement, I started getting the battery charging message. I didn't pay any attention to it. I actually didn't mind the auto start/stop not working. It wasn't until I recently got the "battery protection mode" message that I started looking into things. Mine was opposite yours, when I disconnected the aux battery it wouldn't start and when I reconnected it, it would start. I also measured the voltage on the main battery and it was under 12, I think 10 something. I also put a load tester on it and it was very bad. You can get a load tester for about $25. It's probably old enough you should just replace it, but a load tester would give you a better idea what kind of shape it's in.

Mine must have the software update?

Since I have replaced the main bettery, pulled the f42 fuse, disconnected the aux negative cable, and installed an auto start/stop disabler, I've had no more issues or warnings.

I don't think it can hurt anything leaving the aux batter sitting there disconnected. It would be good to get rid of that dead weight, but that requires more effort, lol.

 

[dazar]

@Rhinebeck01 Thank you for the quick response and detailed information. I will get a new H7 battery (I think that is what is in there now because I have the Tow package). I will also look at adding a SmartsStopStart. Follow-up question regarding the TSB, will I be able to get the dealer to apply that Power Control Update with my AUX bypassed?

 

[Rhinebeck01]

You may be able to get a dealer to do as it would be covered under longer power train warranty. Or you could pay to have dealer do.

I would not bother though. You know now how to deal with your 2018.

If you want to try to have done, do read here https://www.jlwranglerforums.com/forum/threads/ess-dual-battery-management.60034/post-1357760

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