ESS battery , Jeep died

[Captjay17]

2021 JL Sport, 9,500 miles. battery save mode come on and Jeep died shortly after and wouldn't start again. Towed to dealer. No codes no nothing, cannot duplicate they say. They charged the main battery, not sure about ess battery. I'm assuming it takes a charge through main.

If ESS is turned off, will that help main battery? Does it somehow isolate? My wife has 6hr drive to get home.

Trying to figure out what can be done. My thinking from reading many other threads is ess battery drained main battery. But how long will this last since its died already?

Any thoughts appreciated

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[ConqSoft]

Yeah they should have replaced both batteries. If your ESS battery is bad it will continue to drain and eventually kill your main battery again.

 

[Captjay17]

Yeah they should have replaced both batteries. If your ESS battery is bad it will continue to drain and eventually kill your main battery again.

Appreciate it. Thought thats how it was set up. I'm 1400 miles away from her but I spoke to dealership and they said it all checked out fine. I have feeling they did not load test aux. bat. And only checked voltage. Unfortunately at less than 10k miles I'm hesitant to do anything myself or replace the batteries with better other than oem. If I bypass aux and ess I'll probably shoot my warranty.

 

[ConqSoft]

Bypassing the ESS shouldn't affect warranty. Just connect it back before taking it in.

 

[Reinen]

If you're putting that little mileage on a JL, you're either not driving it often or you are taking very short trips. That kills your batteries because they don't get fully recharged on a regular basis. Doing anything with ESS isn't going to do anything. To prevent that, you need to put a trickle charger on the battery when it sits idle. If it is parked outdoors, you can add a solar panel such as the Cascadia 4x4 hood solar panel. That's the easiest solution.

For your situation now, your batteries are shot due to lack of regular recharging. Just recharging them isn't going to resolve it. They can't hold the charge. They should have replaced both Main and Aux batteries, that will resolve everything. Then use the trickle charger or solar panel so this doesn't happen again.

 

[Captjay17]

If you're putting that little mileage on a JL, you're either not driving it often or you are taking very short trips. That kills your batteries because they don't get fully recharged on a regular basis. Doing anything with ESS isn't going to do anything. To prevent that, you need to put a trickle charger on the battery when it sits idle. If it is parked outdoors, you can add a solar panel such as the Cascadia 4x4 hood solar panel. That's the easiest solution.

For your situation now, your batteries are shot due to lack of regular recharging. Just recharging them isn't going to resolve it. They can't hold the charge. They should have replaced both Main and Aux batteries, that will resolve everything. Then use the trickle charger or solar panel so this doesn't happen again.

Garage kept. Yea short drives around town but this time ws a 6hr drive in her Jeep. However, I've never seen issues like this. We've had total of 5 Jeeps and none of her other Jeeps had this issue but they didnt have ess. Hoping she can make it back, she dropping off at another dealership closer to home tomorrow. I'll check into trickle charger. We love the Jeep but between the steering gear last yr and 3 dealerships at 3k miles and now this at 1.5yr old, bit ridiculous. Shes been stranded once because of this.

 

[Fudster]

2021 JL Sport, 9,500 miles. battery save mode come on and Jeep died shortly after and wouldn't start again. Towed to dealer. No codes no nothing, cannot duplicate they say. They charged the main battery, not sure about ess battery. I'm assuming it takes a charge through main.

If ESS is turned off, will that help main battery?

No. If ESS is turned off it simply won't engage ESS, but how the two batteries are connected to each other, which is in parallel at all times but an instant at cold crank, and during ESS events when they are isolated doesn't change.

Does it somehow isolate? My wife has 6hr drive to get home.

In short no. I long, if ESS is allowed to engage then during, and only during ESS events, yes, the two batteries are separated to allow the ESS battery to run appliances, saving the main battery for cranking. To be more precise, at the end of an ESS event both batteries are reconnected in parallel and both energize the crank, the main battery doing most of the work.

Trying to figure out what can be done. My thinking from reading many other threads is ess battery drained main battery. But how long will this last since its died already?

Any thoughts appreciated

Jason: the toolkit of approaches here, assuming its the batteries that have you in this situation are several. First, the only real test of a battery is done with a load tester. Each battery should be load tested independently. The way that this is done is, when the JL is parked and off, by disconnecting the black cable on the main battery's negative post that originates at the ESS battery.

There are two black factory cables there. One leads to the body ground on the passenger's front fender. That cable should REMAIN connected. It's the other one you temporarily remove.

This action temporarily disconnects the two batteries. Load testing of the main battery is done by putting a load tester on the main battery's posts. Load testing of the ESS battery is done by moving the negative lead of the load tester from the main battery's negative post to that dangling cable you just disconnected. Trust me, schematically, this only completes a circuit with the ESS battery.

Let's suppose the ESS battery is shot but not the main. Lets talk about how you can take that ESS battery out of the picture, either temporarily or permanently.

In the thread this post is connected https://www.jlwranglerforums.com/forum/threads/start-stop-battery-out-again.101383/post-2111067 to there is a link to how to effect this ESS battery disconnect without generating error messages.

The post itself of this link discusses a way to do this that generates an error message, but that error message is "ESS off" on the dash. Exactly what you want.

Let me give you the Reader's Digest version of my post. Wrap in electric tape the cable you disconnected for the independent load test. Crank once. It should fail. Crank again. If the main battery has power the vehicle (3.6L) should crank off the main battery, work forever more only off the main battery and throw an ESS off message in the dash.

From that point on the JL should crank on one attempt. Only reintroducing, if you choose, an energized ESS battery and reconnecting it will, on next cold crank, revert the JL back to its use of 2 batteries, turning off the ESS off light (i.e. allowing ESS to engage under the right conditions.)

 

[Reinen]

Garage kept. Yea short drives around town but this time ws a 6hr drive in her Jeep. However, I've never seen issues like this. We've had total of 5 Jeeps and none of her other Jeeps had this issue but they didnt have ess. Hoping she can make it back, she dropping off at another dealership closer to home tomorrow. I'll check into trickle charger. We love the Jeep but between the steering gear last yr and 3 dealerships at 3k miles and now this at 1.5yr old, bit ridiculous. Shes been stranded once because of this.

Yeah, it's a pain. I WFH and have no daily commute so I'm in the same boat. My Jeep either sits idle, takes short town errands or long off-road excursions. So I need to do that too. But it has nothing to do with ESS. It's all the always-on electronics in the JL. Keyless entry, monitoring for remote start signals, etc. Gone are the days when you shut the engine off and nothing is drawing from the battery. Now there's always something drawing power and the batteries need to be recharged on a daily basis, either by driving or an alternate charging method.

All ESS does is complicate things a little bit because instead of a single battery, there's a Main and Aux battery. They're always linked except during starts. One starts the engine, the other keeps the electronics functioning. You have to consider them as a single battery system. You'll go through a lot more batteries in the long run if you only replace them one at a time.

 

[Bilymac]

When I had the same type situation, I had to prompt the Dealership several times to test, then replace the AUX battery. Once they finally did, the problem was solved.

 

[Fudster]

... It's all the always-on electronics in the JL. Keyless entry, monitoring for remote start signals, etc. Gone are the days when you shut the engine off and nothing is drawing from the battery. Now there's always something drawing power and the batteries need to be recharged on a daily basis, either by driving or an alternate charging method.

True...but battery purists would also argue that is is the dissimilar size of the two batteries in parallel that's also part of the problem. At least they are of the same chemistry though.

All ESS does is complicate things a little bit because instead of a single battery, there's a Main and Aux battery. They're always linked except during starts. One starts the engine, the other keeps the electronics functioning.

At cold cranks, yes, for an instant the batteries are isolated where the Aux battery is tested. If you're running a 2018 without TSB 18-092-19 a dead Aux battery will strand you. If you have the TSB or running later model years the second attempt at cranking should switch over to the main battery and disable ESS in the EVIC--keeping things that way until the next cold crank where a charged Aux battery is detected.

When you stay that once cranked "the other keeps the electronics functioning" may not be wrong but deserves clarification. The batteries are also isolated during ESS events, where, yes, the Aux battery keeps the vehicle's appliances running during such events.

 

[Captjay17]

I can't make this up. Latest dealership says the Jeep has bad gas. Say what?! So you mean to tell me that bad gas caused ess to stop working, jeep to stall after the ELECTRICAL WARNING LIGHT came on into power save mode, and had zero power to even turn over? Someone please explain this to me because I've dealt with engines and machinery for years and could have never imagine a more incompetent diagnosis. Correct me if I'm wrong , however I don't belive so. What has happened to Jeep?!? We've had 5 Jeeps since 2007 and have loved them until this.

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