Jeep wouldn't start this Morning

[Jeeperjamie]

That has always been the problem of DC parallel circuits using uneven amp hour rated sources. It would be less problematic had they used two batteries of equal value.

While not privy to how FCA/Jeep designed this ESS system of having dual batteries, I have a suspicion that they accepted the trade off of knowing both batteries would likely go down about the same time to keep steady load to the vehicle electronics vs. other makes who use a single battery for their ESS systems but accept a less stable load when the main battery becomes marginal.

I think to them, it came down to a "pick your poison" and they just ran with this dual battery setup.

I can agree with that. I've also talked to a few guys with the same system as we have in their JLs who have over 100,000 miles on their jeeps and haven't replaced the small battery yet but have replaced the big battery once. My neighbors has a 2018 and another guy a 2019, neighbors got 127,000 on his JLU and his small battery has never been replaced. I wonder if replacing the small battery when it's not the issue and keeping a bad big battery would cause a new small battery to wear out prematurely or sooner than it would.

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[Deleted member 28696]

Looks good but I had the big replaced and all is good now. The system seems nice but I'll just stick to what's stock. I feel like a lot of these battery issues are misdiagnosed from the feedback I've been getting and things I've been reading. As with a lot of vehicles, if they sit for awhile they won't start because of a dead battery. Although I feel like the big battery should of lasted longer than it though.

I hear ya, felt the same way until I had replaced both of those batteries twice in a short amount of time. That’s why I swapped it out for something better. It won’t void your Jeep warranty since your not changing anything about the electrical system of the vehicle or how it works the only thing your doing is swapping for a bigger dual battery with an isolator, the batteries or Genesis system won’t be directly warranted by Jeep but that’s to be expected. Some dealerships are apparently putting these Genesis systems in vehicles prior to sale. With Jeep you have to swap the unreliable components with something that works & that is more robust.

 

[Jeeperjamie]

I hear ya, felt the same way until I had replaced both of those batteries twice in a short amount of time. That’s why I swapped it out for something better. It won’t void your Jeep warranty since your not changing anything about the electrical system of the vehicle or how it works the only thing your doing is swapping for a bigger dual battery with an isolator, the batteries or Genesis system won’t be directly warranted by Jeep but that’s to be expected. Some dealerships are apparently putting these Genesis systems in vehicles prior to sale. With Jeep you have to swap the unreliable components with something that works & that is more robust.

True, I'm out of warranty anyway. 58,000 miles on mine so warranty isn't a issue. I'm just thinking about price of a new battery vs the Genesis system. Like how many times would I have to replace a battery before I see the pay back. Not knocking it though, it looks like a great system

 

[Deleted member 28696]

True, I'm out of warranty anyway. 58,000 miles on mine so warranty isn't a issue. I'm just thinking about price of a new battery vs the Genesis system. Like how many times would I have to replace a battery before I see the pay back. Not knocking it though, it looks like a great system

Yeah it’s fairly expensive, mostly due to the costs of the group 25 AGM batteries which was more than the Genesis system itself. I knew it would continue be a hassle having to deal with dead batteries time & again & dealing with Jeep service so I chose to confront the issue head on & hopefully this solves it long term, so far so good.

 

[Gvsukids]

I've been having the warning everyday to service my stop-start system. It wouldn't be so bad if it didn't kill the battery or turn off my traction control.

 

[Gvsukids]

My update is that the dealership found the connector to the vacuum pump was loose from the previous time the Jeep was in for service. After closing the connector the ess error went away.

 

[XJADDICTION]

Can’t say y’all didn’t warn me! My baby battery died and no Jeep start this am. I luckily watched lite brite how to on jumping the battery to get it going and using a lug nut to bypass temporarily the baby battery but decided to leave it at home until I can properly delete the baby start stoop battery. I think mine lasted as long as it did because I deleted the start stop with the Tazer Moni… I love that thing.

will I still be able to remote start the JT without the baby battery? I haven’t researched yet as I’ve been at work today and no time.

was sad but had to drive the GT Mustang to work today… ?

 

[ShadowsPapa]

I think mine lasted as long as it did because I deleted the start stop with the Tazer Moni… I love that thing.

Has nothing at all to do with it. Allowing auto stop/start to work or not to work has no impact on the life of the battery.

In almost all cases you can jump start with no special attention to anything.
I've jump started Jeeps multiple times with bad aux batteries and always did it just like any other vehicle.
Not sure how a lug nut can bypass a battery - you'd literally have to disconnect the battery to have it out of the system.

 

[Jeeperjamie]

Can’t say y’all didn’t warn me! My baby battery died and no Jeep start this am. I luckily watched lite brite how to on jumping the battery to get it going and using a lug nut to bypass temporarily the baby battery but decided to leave it at home until I can properly delete the baby start stoop battery. I think mine lasted as long as it did because I deleted the start stop with the Tazer Moni… I love that thing.

will I still be able to remote start the JT without the baby battery? I haven’t researched yet as I’ve been at work today and no time.

was sad but had to drive the GT Mustang to work today… ?

I'll bet it's your big battery not the small battery. Same thing happened with mine, ended up being a dead cell in the big battery. My small battery is still going strong.

 

[Mr._Bill]

I'll bet it's your big battery not the small battery. Same thing happened with mine, ended up being a dead cell in the big battery. My small battery is still going strong.

I bought both batteries. My originals are over three years old. I have not changed the small one, yet, due to the time required. After changing the main battery a couple weeks ago, everything is back to normal.

 

[ShadowsPapa]

My originals are over three years old.

That's good from what I've been learning about modern batteries in modern vehicles, especially with the heat.

25 degrees today, mine was charging at 15.0 volts for part of the trip.
Hmmm, has Jeep made some changes?

 

[Mr._Bill]

That's good from what I've been learning about modern batteries in modern vehicles, especially with the heat.

25 degrees today, mine was charging at 15.0 volts for part of the trip.
Hmmm, has Jeep made some changes?

We have a Compass that we got a month after the truck. I had to replace the main battery in it earlier this year. It is still running on the original Aux battery.

 

[Jeeperjamie]

I bought both batteries. My originals are over three years old. I have not changed the small one, yet, due to the time required. After changing the main battery a couple weeks ago, everything is back to normal.

I just turned 62,000 on mine and the smalls still going. The big went out at 56,000. It's crazy how the life spans are all over the place on these things. I guess environment and other factors come into play. The small will be 3yrs old in February

 

[XJADDICTION]

That's good from what I've been learning about modern batteries in modern vehicles, especially with the heat.

25 degrees today, mine was charging at 15.0 volts for part of the trip.
Hmmm, has Jeep made some changes?

my main battery reads 12 volts on volt meter and the baby battery appears to be dead. This is from the JL Forum and is a common problem with this Jeep JT and JL forum with the start stop.

“Here's the battery voltages on a working system, the PCR is connecting the batteries in parallel, both batteries providing power to everything. Normal operation is verified with 0 volts between N1 and N2.”

“Bypassing is accomplished by jumping N1 to N2. This diagram illustrates the jumper getting power back to the critical electronics.”

“Bypassing is accomplished by jumping N1 to N2. This diagram illustrates the jumper getting power back to the critical electronics.”

my problem is definitely the baby battery and it goes bye bye tomorrow. ?

https://www.jlwranglerforums.com/forum/threads/jumperless-aux-battery-bypass.95945/

 

[ShadowsPapa]

They aren't bypassing anything. That's the confusion. They are jumping crank battery to electronics.
Since the batteries are in parallel, the crank battery actually is connected to N1 at all times as long as the PCR is closed.
Your main battery at 12 volts means it's dead or near dead - not enough to start the vehicle.
The cables are large enough the voltage drop would be minimal.
The explanations floating around are flawed.
The one and only way an aux battery could act this way is with an internal short. It's not that common and those who "need" to jump N1 to N2 have some other issues going on but are convinced of what they believe so there's no fixing that.

Read my discussions on batteries, voltages and other fun Jeep electrics.

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