VIDEO : HOW TO Replace the Main & Auxiliary Battery on a JL Wrangler / JT Gladiator

kevman65

Hooked
Just wondering, has anyone tried the way the tech manual shows and gone from the bottom to replace the AUX battery?

Fold the fender liner out of the way, 3 bolts, and the bottom half of the case drops down with battery in it.
 

wayoflife

Administrator
Staff member
Just wondering, has anyone tried the way the tech manual shows and gone from the bottom to replace the AUX battery?

Fold the fender liner out of the way, 3 bolts, and the bottom half of the case drops down with battery in it.
LOL - For the love of god, I hear internet experts tell me all the time that is the "best" way to do it. Like I asked or even care. Not saying that you are and realize you're just asking but holy cow.

Yes, I have tried doing it both ways and so far as I could tell, there is no simple "folding the fender liner out of the way" or at least, not very easily. Hell, it annoys the hell out of me just to try and remove the upper shock bolt being that the stupid fender liner, the one that should just fold out of the way is always in the way! If you want to go from below, you NEED to remove the fender and the liner comes with it. In order to do that, you need to remove 4 bolts, pull one push tab that you will most likely break and then, as the fender comes off, you will most likely break MOST of the fender clips or at least, on newer JL's and JT's. If you buy Mopar replacements, these cost $4 a piece. If you buy cheap ones off of Amazon, they will not fit unless you cut the center holes on the fenders out. Anyway, after the fender is pulled, you need to unplug the DRL/indicator light and then, it can come completely free of the body. It is only after all this that you can get to the bolts securing the bottom of the auxiliary battery tray to the main tray.

Having tried doing it both ways, I can tell you that it takes JUST AS LONG to do as going from above and again, you will most likely break most of your fender clips. That said, I think it's great that people have more than one way to do things and clearly, they should use whatever method they feel is best for them. (y)
 

OverlanderJK

Resident Smartass
LOL - For the love of god, I hear internet experts tell me all the time that is the "best" way to do it. Like I asked or even care. Not saying that you are and realize you're just asking but holy cow.

Yes, I have tried doing it both ways and so far as I could tell, there is no simple "folding the fender liner out of the way" or at least, not very easily. Hell, it annoys the hell out of me just to try and remove the upper shock bolt being that the stupid fender liner, the one that should just fold out of the way is always in the way! If you want to go from below, you NEED to remove the fender and the liner comes with it. In order to do that, you need to remove 4 bolts, pull one push tab that you will most likely break and then, as the fender comes off, you will most likely break MOST of the fender clips or at least, on newer JL's and JT's. If you buy Mopar replacements, these cost $4 a piece. If you buy cheap ones off of Amazon, they will not fit unless you cut the center holes on the fenders out. Anyway, after the fender is pulled, you need to unplug the DRL/indicator light and then, it can come completely free of the body. It is only after all this that you can get to the bolts securing the bottom of the auxiliary battery tray to the main tray.

Having tried doing it both ways, I can tell you that it takes JUST AS LONG to do as going from above and again, you will most likely break most of your fender clips. That said, I think it's great that people have more than one way to do things and clearly, they should use whatever method they feel is best for them. (y)
All that I would guess is accurate but I would think reason enough to not do it is a little thing called gravity. I would rather work from above than below.
 

kevman65

Hooked
LOL - For the love of god, I hear internet experts tell me all the time that is the "best" way to do it. Like I asked or even care. Not saying that you are and realize you're just asking but holy cow.

Yes, I have tried doing it both ways and so far as I could tell, there is no simple "folding the fender liner out of the way" or at least, not very easily. Hell, it annoys the hell out of me just to try and remove the upper shock bolt being that the stupid fender liner, the one that should just fold out of the way is always in the way! If you want to go from below, you NEED to remove the fender and the liner comes with it. In order to do that, you need to remove 4 bolts, pull one push tab that you will most likely break and then, as the fender comes off, you will most likely break MOST of the fender clips or at least, on newer JL's and JT's. If you buy Mopar replacements, these cost $4 a piece. If you buy cheap ones off of Amazon, they will not fit unless you cut the center holes on the fenders out. Anyway, after the fender is pulled, you need to unplug the DRL/indicator light and then, it can come completely free of the body. It is only after all this that you can get to the bolts securing the bottom of the auxiliary battery tray to the main tray.

Having tried doing it both ways, I can tell you that it takes JUST AS LONG to do as going from above and again, you will most likely break most of your fender clips. That said, I think it's great that people have more than one way to do things and clearly, they should use whatever method they feel is best for them. (y)
Glad I didn't ask where Hoffa's body was buried 🤪
 

wayoflife

Administrator
Staff member
Glad I didn't ask where Hoffa's body was buried 🤪
LOL - Like I said, it's not on you. I just can't tell you how many times I get people on YouTube posting on this video to tell me how I'm doing it wrong or how their way is better or whatever. And, some of them are down right nasty about it - like I've somehow called them them the wrong pronoun or something. It's just weird.
 

kevman65

Hooked
LOL - Like I said, it's not on you. I just can't tell you how many times I get people on YouTube posting on this video to tell me how I'm doing it wrong or how their way is better or whatever. And, some of them are down right nasty about it - like I've somehow called them them the wrong pronoun or something. It's just weird.
Only reason I asked, I know a tech from one of the dealerships and he showed me the Tech Bulletin showing the process and it's from the bottom.
In it they don't remove the fender or the liner, just pop the liner loose so it folds away from engine and frame. No video, just pictures, and it's hard to tell how much trouble it is just from stills.
 

wayoflife

Administrator
Staff member
Only reason I asked, I know a tech from one of the dealerships and he showed me the Tech Bulletin showing the process and it's from the bottom.
In it they don't remove the fender or the liner, just pop the liner loose so it folds away from engine and frame. No video, just pictures, and it's hard to tell how much trouble it is just from stills.
Sorry, never seen the tech bulletin but I have personally tried doing it both ways. That said, I honestly don't know how you "just pop the liner loose". I mean, it's riveted and plastic welded to the fender structure and bolted onto the body with 2 bolts. Sure, the liner is somewhat flexible enough to bend with force but there's no way it just "folds away" from the engine and frame. I would encourage you to try it for yourself.
 

kevman65

Hooked
Sorry, never seen the tech bulletin but I have personally tried doing it both ways. That said, I honestly don't know how you "just pop the liner loose". I mean, it's riveted and plastic welded to the fender structure and bolted onto the body with 2 bolts. Sure, the liner is somewhat flexible enough to bend with force but there's no way it just "folds away" from the engine and frame. I would encourage you to try it for yourself.
What, and cause blood and suffering on myself? 🤪

Always ask first. My JT is 3 years old this month, so I figure this chore is coming up.
 

wayoflife

Administrator
Staff member
What, and cause blood and suffering on myself? 🤪

Always ask first. My JT is 3 years old this month, so I figure this chore is coming up.
LOL - too funny but for better or for worse, this is a chore you will have to do soon.

And, so it's clear, I never said that going from below is wrong or a bad way to do things. I just don't think it's as fast or as easy as the internet experts will try and tell you.
 

RanchoRubi

Caught the Bug
So I did the replace today. Did it from the top per Eddie’s video. Was straightforward. Easier than I thought.
But….. since Jeep tolerances aren’t consistent, dealing with the aux battery and reconnecting the leads was a PITA. Got the same aux batt as Eddie. Not a lot of clearance between top of aux batt and plastic mount that goes on top. So orientation of leads and wires is critical. Given that, regardless of dealing with fender liner, it would have be horrific to try to synch it up through a bottom approach. Sorry I didn’t take pics.
FWIW, these stock batteries go like clockwork between 32-36 mos. My Jeep turned 35 months.
And I would not try the bottom approach.
thanks for the how to instruction, Eddie
 

RanchoRubi

Caught the Bug
Also, I was pleasantly surprised by the Jeep design and approach of the multi layer trays. Sure there’s a few bolts, but it’s robust and well designed.
 

wayoflife

Administrator
Staff member
So I did the replace today. Did it from the top per Eddie’s video. Was straightforward. Easier than I thought.
But….. since Jeep tolerances aren’t consistent, dealing with the aux battery and reconnecting the leads was a PITA. Got the same aux batt as Eddie. Not a lot of clearance between top of aux batt and plastic mount that goes on top. So orientation of leads and wires is critical. Given that, regardless of dealing with fender liner, it would have be horrific to try to synch it up through a bottom approach. Sorry I didn’t take pics.
FWIW, these stock batteries go like clockwork between 32-36 mos. My Jeep turned 35 months.
And I would not try the bottom approach.
thanks for the how to instruction, Eddie
Aside from the tolerance issues you encountered, I'm glad to hear things were easier than you thought it would be. Thanks for reporting back on how things went and to confirm going through the top worked out well for you.
 

wayoflife

Administrator
Staff member
I have seen the tech bulletin and let me tell you, it’s not worth doing it from the bottom. Tried it on a used JL that we had and I gave up. Had it out he top in 10 mins max.
Glad to hear it and thanks for letting us know! (y)
 

SHeard

New member
VIDEO : HOW TO Replace the Main & Auxiliary Battery on a JL Wrangler / JT Gladiator

Having your Jeep battery die really isn’t that big of a deal, especially if you have a set of jumper cables handy and another vehicle near by that's willing to help out. But, what do you do if you're out in the middle of nowhere and all alone? That just happened to Cindy and I and if you can believe it, on our Jeep JL Wrangler that's only about two years old! Fortunately, we did have our super compact, Type S Jump Starter with us and that was able to get us going again. However, once we got home, we discovered that our battery still wasn't holding a charge or at least, not enough to fire up the engine. All the lights worked, the radio played, windows opened and closed and even the dash lit up just fine - there just wasn't enough juice to get it to get it to crank.

Well, as some of you may or may not know, the Jeep JL Wrangler and JT Gladiator Truck has two batteries under the hood - a large traditional size battery that's used for cranking the engine and a smaller auxiliary one that powers everything else, including a relay that connects the two batteries together for cranking. Needless to say, even if your main battery wasn't dead, you could still have problems starting your engine if your auxiliary battery is dead or dying. I should note that we were actually seeing strange messages on the dash EVIC including one for, Aux Switches being temporarily disabled due to "Battery Charging" and another saying, "Service Shifter". So, when it comes time to replace one, you're more than likely going to need to replace both and for us, we decided to use the opportunity to upgrade our main battery to an Odyssey. I wish we could have upgraded our auxiliary one too but there really isn't a whole lot to choose from and so I just got a Super Start Platinum from my local O'Reilly Auto Parts Store. In this video, you'll get to see just how easy it is to replace the main battery AND what all you'll need to do to replace the auxiliary one. We hope it helps you out.


Type S Jump Starter: https://amzn.to/31fyFRI
Odyssey Battery 48-720: https://amzn.to/3eB8FmU
Milwaukee Cordless Ratchet: https://amzn.to/3fLGao3
Tekton Torx/E-Sockets: https://amzn.to/3jpCvhB

#wayalife #odysseybattery #oreilly #milwaukee #tekton
Great tutorial. You make it look so easy. I've always carried a jump starter in each of my vehicles as a precaution. I also recently bought a trickle charger/maintainer to hook up to my 2019 JLUR for when it sits for an extended period. My question is do I just hook it up to the main battery terminals? Will doing this keep the hidden starter battery charged as well?
 

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Don't know about the aux battery charging, but I keep a high quality battery charger/maintainer (CTEK MULTI US 7002) on the main battery most of the time since I am not a daily driver (work from home). A sudden main battery failure on the very morning we were to start a 2000 mile round trip through very remote places really freaked me out. The Jeep turned into a pinball machine overnight!
 

wayoflife

Administrator
Staff member
Great tutorial. You make it look so easy. I've always carried a jump starter in each of my vehicles as a precaution. I also recently bought a trickle charger/maintainer to hook up to my 2019 JLUR for when it sits for an extended period. My question is do I just hook it up to the main battery terminals? Will doing this keep the hidden starter battery charged as well?
I'm not 100% sure but I'm pretty sure that you can just hook up to the main battery and it'll get the job done.
 
I went through this post and didn’t see this question get asked. Has anyone tried to replace the aux battery with a full size one?

Not a dual battery setup, but using a dual battery setup, just not tying the batteries together. Using the second battery as the aux battery?

Seems like you could just extend the battery connections to the second battery in the dual battery setup?

This would probably make the battery last a lot longer and put the battery in a place that’s much easier to change.

I’ve looked at it a little and I can’t see a reason why this can’t be done. This may become a winter project if I can’t find a reason NOT to do this. I’m on aux battery #4 for a 2018 with 24k miles.
 

TomF

New member
Thanks to Wayalife's Battery Replacement video for making me much more confident in doing this. It took me an hour and twenty minutes and I am a novice in auto maintenance. The hardest part was removing and reinstalling the plastic tray that the PDC plastic box rests upon. You have to slide it under some tightly stretched harnesses. All in all, not too bad and a successful completion. I think, for me, this method is better than pulling the fender....just my opinion and I am sure others feel removing the fender is easier.
 
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