Battery, Second Battery, and Jump Starting

[BoomerangJ]

I store my 2022 Gladiator with ~7k miles on it for a couple of months at a time. The first year-no issue-after a couple of months it started right up. Earlier this year it was completely dead. I jumped it got it going to look it to the dealer for scheduled service. They said both batteries were fine just low on charge. I tickle charged them and no issue except I think the secondary battery never recovered as the auto off at stop signs never worked. I left again for a couple of months-but installed a battery tender on the main battery. Came back it started right up-that was last Sunday. Drove it M-W. Today on Friday the battery was low enough that it couldn't start. I put the transfer case in neutral and pushed it out of the garage (auto tranny remained in park). Hooked up the jumper cables and tried to start it and it flashed "auto park dis-engaged-keep transmission in drive and drive to nearest dealer". But the starter will not engage at all-like it's locked out. Tried to shift the transfer case back into 2H but it will not let me shift it. Several questions! How can I jump start it? What is up with these batteries, especially the secondary battery? I don't give one crap for the auto off function-It's the first button I hit to turn it off when it was working. My number is 512-423-2179 if someone wants to call me. Thanks!

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[Mr._Bill]

The two batteries are paralleled together all the time. The only time they are separated is during ESS events and the startup test.

The JT computers never turn off. It has a large parasitic draw. The 8.4 head unit increases the load. If the truck is not being driven enough to keep the batteries charged, then it needs to have a battery maintainer connected.

The batteries can be ruined if they become fully discharged. You survived the first year due to new batteries, but it was downhill from there.

You may be able to recover by disconnecting the batteries and separately charging each one with a good AGM charger. You may need to buy new batteries and a maintainer and start over.

 

[Mr._Bill]

The OEM batteries are not known for their quality or longevity. I got over three years out of mine, but it was driven regularly. When the main gave out, a year ago, I replaced it with a ACDelco 94R from Amazon. The Aux battery died about six months ago. I have one to replace it, just haven't got it done yet.

 

[Andy29847]

The Jeep battery design is not the best thing about the truck. I've changed mine to just one battery. Everything still works the same. To do this, I disconnected the aux battery and removed fuse F42. I re-placed the 2 Mopar batteries (big one is 700 CCA, little one is 200 CCA) with an Everstart H7/Group 94 battery. The new battery is 850CCA and comes with a 4 year warranty. Best of all, The battery system in my truck works like all the cars and trucks I have had for the last 50 years.

The "Battery Talk" section of this forum has tons of good info but it can be hard to find the right stuff. Here is a good place to start: 3.6L ESS Battery Cable Diagram | Jeep Gladiator (JT) News, Forum, Community - JeepGladiatorForum.com

This thread is the skinny on deleting the aux battery: Jumperless aux battery/PCR bypass | Jeep Gladiator (JT) News, Forum, Community - JeepGladiatorForum.com

 

[Medical_Bartender]

Anyone have a suggestion on a good trickle charger for these trucks? I'll be going on a 9 month "vacation" of sorts and intend to leave it on the charger for that time.

 

[BoomerangJ]

The two batteries are paralleled together all the time. The only time they are separated is during ESS events and the startup test.

The JT computers never turn off. It has a large parasitic draw. The 8.4 head unit increases the load. If the truck is not being driven enough to keep the batteries charged, then it needs to have a battery maintainer connected.

The batteries can be ruined if they become fully discharged. You survived the first year due to new batteries, but it was downhill from there.

You may be able to recover by disconnecting the batteries and separately charging each one with a good AGM charger. You may need to buy new batteries and a maintainer and start over.

Thanks for the response. It's at the dealer now. Sounds like they are going to put in a new auxiliary battery and maybe a new main battery. I read the forums and I can't confirm if the battery tender on the main will keep the auxiliary battery topped off? Or do I need a second battery tender for the auxiliary battery and somehow connect it to the terminals that go to the auxiliary battery? Any thoughts/advice on the "best" battery tender setup?

 

[BoomerangJ]

Anyone have a suggestion on a good trickle charger for these trucks? I'll be going on a 9 month "vacation" of sorts and intend to leave it on the charger for that time.

I've used the battery tender brand on boats, in the heat of Texas, and I've been able to get 5 years out of my batteries. More importantly the boat always started! Nothing like getting ready for some fun and the boat won't start! Same with this jeep!!

 

[BoomerangJ]

The Jeep battery design is not the best thing about the truck. I've changed mine to just one battery. Everything still works the same. To do this, I disconnected the aux battery and removed fuse F42. I re-placed the 2 Mopar batteries (big one is 700 CCA, little one is 200 CCA) with an Everstart H7/Group 94 battery. The new battery is 850CCA and comes with a 4 year warranty. Best of all, The battery system in my truck works like all the cars and trucks I have had for the last 50 years.

The "Battery Talk" section of this forum has tons of good info but it can be hard to find the right stuff. Here is a good place to start: 3.6L ESS Battery Cable Diagram | Jeep Gladiator (JT) News, Forum, Community - JeepGladiatorForum.com

This thread is the skinny on deleting the aux battery: Jumperless aux battery/PCR bypass | Jeep Gladiator (JT) News, Forum, Community - JeepGladiatorForum.com

Yes! I think this will be my plan. The Jeep is at the dealer now and they even talk bad about this auxiliary battery. That setup should win an award for the worst car design feature ever. A Battery that requires the inner fender to be remove or to remove the electronics sitting on top of it!! For now it's covered under warranty and I'm getting new batteries. I'm also not a fan of the ESS. Makes me feel like I'm driving a golf cart and not a big bad Jeep Gladiator Mojave! LOL! What really bothers me is I use this Jeep in Arizona and I take it out in the desert. This Jeep started just fine M-T-W. Didn't drive it on Thursday. Friday it was dead. Had I been out in the desert with no phone service 25 miles from help and a dead auxiliary battery-not good. Just a reminder that I need to pack more water then I think I will need. But for a vehicle like this to have an unreliability issue of this nature is ridiculous. Makes me kinda wish I had my 1977 Jeep CJ back! Man was that vehicle simple!

 

[sharpsicle]

I read the forums and I can't confirm if the battery tender on the main will keep the auxiliary battery topped off? Or do I need a second battery tender for the auxiliary battery and somehow connect it to the terminals that go to the auxiliary battery?

They're in parallel when at rest. One will maintain both.

Only time the batteries are separate is when ESS is active or at the extremely-quick momentary startup test.

 

[Mr._Bill]

Thanks for the response. It's at the dealer now. Sounds like they are going to put in a new auxiliary battery and maybe a new main battery. I read the forums and I can't confirm if the battery tender on the main will keep the auxiliary battery topped off? Or do I need a second battery tender for the auxiliary battery and somehow connect it to the terminals that go to the auxiliary battery? Any thoughts/advice on the "best" battery tender setup?

The batteries are paralleled together, so one connected to the nuts on top of the main battery will keep both batteries charged.

Get a battery tender like you would use for the boat. It just needs to be one compatible with AGM batteries.

 

[Mr._Bill]

Yes! I think this will be my plan. The Jeep is at the dealer now and they even talk bad about this auxiliary battery. That setup should win an award for the worst car design feature ever. A Battery that requires the inner fender to be remove or to remove the electronics sitting on top of it!! For now it's covered under warranty and I'm getting new batteries. I'm also not a fan of the ESS. Makes me feel like I'm driving a golf cart and not a big bad Jeep Gladiator Mojave! LOL! What really bothers me is I use this Jeep in Arizona and I take it out in the desert. This Jeep started just fine M-T-W. Didn't drive it on Thursday. Friday it was dead. Had I been out in the desert with no phone service 25 miles from help and a dead auxiliary battery-not good. Just a reminder that I need to pack more water then I think I will need. But for a vehicle like this to have an unreliability issue of this nature is ridiculous. Makes me kinda wish I had my 1977 Jeep CJ back! Man was that vehicle simple!

No one really likes ESS, but you can blame the EPA for having to put up with it. The two battery design is not the problem, Mercedes has been using it for at least a decade. The Jeep implementation is not the best. Their problem was no space in the engine bay to make the battery easily accessible.

 

[Lunentucker]

With the one exception of this actually NOT disabling the ESS system, it's the quick and easy.
Read the description for details

 

[Outback_Joe]

If you have a power outlet where you store your truck get a good trickle charger/battery maintainer. I drive mine most of the time but not long enough to completely charge both batteries, so I keep a trickle charger on it. This really helps in the wintertime to, the truck jumps to life even on minus zero mornings.

 

[Outback_Joe]

Anyone have a suggestion on a good trickle charger for these trucks? I'll be going on a 9 month "vacation" of sorts and intend to leave it on the charger for that time.

I have been using this charger for about a year. Very happy with it since it can be used on AGM as well as standard wet batteries.

From Amazon

 

[JW Jeep]

This is what I use. I hook it up easily through trailer plug when I am not using vehicle enough. It’s has worked great

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