Main battery and Aux Battery replacement write up

[MudderNuker]

I drove the Gladiator for a couple of hours yesterday doing some errands and had no starting issues. The temperature dropped to low 20s last night and this morning I attempted to remote start the truck and it didn't start. I got in and tried to start it by pressing the button, but all hell broke loose. It turned into a Xmas tree with all lights and all kinds of clicking noises. The only way to reset everything was to disconnect the ground terminal from the main battery and the N1 terminal on the fuse box. Luckily, I had my NOCO jump pack at the ready. It started right up after reconnecting the terminals. Obviously the two battery design is not optimal on these trucks. On our old WK2 Grand Cherokee without ESS the original battery lasted 8 years. The Gladiator's barely made to 4.

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[MudderNuker]

I drove the Gladiator for a couple of hours yesterday doing some errands and had no starting issues. The temperature dropped to low 20s last night and this morning I attempted to remote start the truck and it didn't start. I got in and tried to start it by pressing the button, but all hell broke loose. It turned into a Xmas tree with all lights and all kinds of clicking noises. The only way to reset everything was to disconnect the ground terminal from the main battery and the N1 terminal on the fuse box. Luckily, I had my NOCO jump pack at the ready. It started right up after reconnecting the terminals. Obviously the two battery design is not optimal on these trucks. On our old WK2 Grand Cherokee without ESS the original battery lasted 8 years. The Gladiator's barely made to 4.

Got my batteries two days ago but it hasn't stopped snowing. Hope to install soon.

 

[MudderNuker]

So finally the weather cooperated and we had temperatures above freezing so I decided to take advantage of balmy 38 degree garage and replaced both batteries. I started at 11:56 and was done at 12:29 (same day ). Exactly 35 minutes including looking for some tools. I went in from the top and it is a very simple and easy process. I believe it is even easier than going through the wheel well which requires lifting the Jeep and removing a heavy tire plus removing the plastic rivets which would probably take longer. Started right up with no warning lights or errors.

 

[69charged]

Well, add me to the list I think. Truck was running great, no messages or anything. Then it got down to -39 Celsius and went out to start it and nothing. Just a click as of the starter was trying. Then the message starter protection enabled. Wait 1:59 seconds. So I waited, tried again and same click then same message. Of course I was trying to get to work so I tried a few more times and I could smell an electrical burning smell from drivers side where the starter is. I got a flashlight and could see the ribbon cable had gotten pretty hot.
Today I tried to boost it, and you could tell it was a pretty heavy load on the running truck. So I pulled the batteries out and tested them. 12.1V on the big one, and 9.2V on the small one. So I’ll charge them up , and try the voltage test again. I also load tested the big battery for 700 CCA and it came back weak, and the small one at 300 CCA and it failed miserably!!
So I think I’ll charge them for a day and see but not holding my breath they are ok.
For reference, mine is a 23 diesel with 66,000kms on it.
Also for anyone reading this in the future, the aux battery is extremely easy to get out. It is under the main battery under a little door. Remove big battery, open little door and take aux battery out.

 

[69charged]

So, as a follow up, I put the main battery on charge for several hours and load tested again. it came back good-weak. So, I charged the small one for about an hour and tested it as well. Also came back good-weak. I am going to buy 2 new batteries today and see what happens. If it still won't start, I guess it will have to get towed to the dealer. Possibly the starter?

 

[MudderNuker]

So, as a follow up, I put the main battery on charge for several hours and load tested again. it came back good-weak. So, I charged the small one for about an hour and tested it as well. Also came back good-weak. I am going to buy 2 new batteries today and see what happens. If it still won't start, I guess it will have to get towed to the dealer. Possibly the starter?

Good luck! I believe new batteries will fix the issue. Both of the batteries I took out read between 12.45 and 12.6V. You would think they were still good but not the case.

 

[Wilsonb80]

Adding to the list, replaced the Main back in January now i have the crazy A and remote start will not work.. Ugg time for the AUX battery. wish me luck.

 

[69charged]

Got both batteries installed, and tried it out. Same thing. You can hear the starter solenoid click and hold for about 5 seconds then release. No start. Will not turn over at all.
Also found out that I had the smaller battery in my diesel. After all the reading I did I thought that jeeps equipped with the tow package came with the bigger battery. I had to remove the little plastic spacer in the battery tray to put in a 94R battery. And my fabric battery cover won’t go back on. Oh well. That was a mouse attractant anyway.
To the dealer it goes!!

 

[Jim SoG]

Not to be a pain, but what is the largest AGM that will fit in stock spot on a gas JT?

Jim

 

[Mr._Bill]

Not to be a pain, but what is the largest AGM that will fit in stock spot on a gas JT?

Jim

94R (H7)

 

[Jim SoG]

Thank you sir.

 

[G_S]

Going to replace both batteries this this weekend.
If I am doing it, why not just do both & be done with it.....

But on what order do I do?
Which one first?
Main or Aux ?

 

[ShadowsPapa]

Going to replace both batteries this this weekend.
If I am doing it, why not just do both & be done with it.....

But on what order do I do?
Which one first?
Main or Aux ?

Doesn't matter. But be bloody well sure to separate the two ground cables from each other and keep the ends from touching ground if doing the main first - as the aux battery will still keep the system hot.

CHARGE BOTH before installing! Don't install new batteries without installing them.
Disconnect the IBS while doing this - it will reset.
As FCA says "only reinstall the IBS onto fully charged new batteries".

As to other comments, no you do not have to lift the vehicle and take off a wheel to replace the aux battery if you don't go through the top. They believe it's harder because they read that's the only way to do it. It's not. Crank the wheels hard and you can pull some of the clips and get to the aux battery if you don't want to go through the top.
The top method isn't without risks - as some have found out, things can get out of alignment and some have had electrical issues after, but it's also not bad, either

 

[G_S]

Just wanted to update

I am not the most mechanical
And over all did not think it was that bad
A little bit of a pain, but not that bad.

Went for the wheel well method

 

[Mr Miami]

For the love of God, please don't turn this into another oil thread...

You may try to trivialize the issue but I did wake up today after losing sleep due to flashes of 0W30 and 5W30 appearing in my dreams. My wife told me to stop mumbling Pennzoil Ultra and Mobil 1 as I was sleeping.

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