How do I know if main battery or ESS battery is causing my issues?

[ForeOSU]

Jeep sat for 5 days and when I tried to start it, it was dead. Jump starting works and brings it back to life for a few days. But then the issue repeats.

Battery is about 3.5 years old so I’m ok buying a new one. But I want to make sure it is truly the main battery and not an ESS battery issue.
Thoughts?

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[ForeOSU]

Should have added - it’s a 2020 3.6L

 

[Chocolate Thunder]

Have both batteries tested. It doesn’t sound like ESS, sounds like a dying or weak battery.

 

[Dusty Dude]

Disconnect the negative on the aux battery and pull Fuse 42. This will eliminate the aux battery from the system. Then try for a couple of days. If the problem goes away, your aux battery is bad. If the problem is still there, replace both batteries. Another option would be to replace just the main battery and leave the aux battery disconnected.

 

[ForeOSU]

Tha

Disconnect the negative on the aux battery and pull Fuse 42. This will eliminate the aux battery from the system. Then try for a couple of days. If the problem goes away, your aux battery is bad. If the problem is still there, replace both batteries. Another option would be to replace just the main battery and leave the aux battery disconnected.

Thanks. Will plan to do this. Stupid question as I am mechanically declined -any illustrations on how to disconnect the negative on the aux battery? Want to make sure I’m disconnecting the correct thing.

 

[garyji]

2020 on OEM Batteries. They both need to be replaced ASAP.

G.

 

[Dan M.]

You are better of replacing both at the same time. Even if your current problem is only from one battery, the other one will likely die soon and you will be in the same situation.

 

[dchemphill1]

Tha

Thanks. Will plan to do this. Stupid question as I am mechanically declined -any illustrations on how to disconnect the negative on the aux battery? Want to make sure I’m disconnecting the correct thing.

It would be the smaller black battery cable. Tape up the end really good. and tuck it away so it does not touch metal.

 

[garykk]

From what you describe, it sure sounds like you aux. battery killed the main battery. And after several times your main is probably ruined too. Like most have said, replace both.

 

[lefflerp]

My 2020 did the same thing a few weeks ago. I let it sit for a week. The lights on the dash would come on but the Jeep would not start. I replaced both the main battery (Optima yellow top) and aux battery (O’Reilly) and all issues went away. When changing the aux go in under the passenger fender.

Also, a few months ago I noticed the electronics, temp control, etc. were slow to turn on/respond when first starting the Jeep. I think this a good indicator that it’s almost time to replace one or both of the batteries.

Good luck!

 

[regreen61]

Jeep sat for 5 days and when I tried to start it, it was dead. Jump starting works and brings it back to life for a few days. But then the issue repeats.

Battery is about 3.5 years old so I’m ok buying a new one. But I want to make sure it is truly the main battery and not an ESS battery issue.
Thoughts?

Even though I hit the auto stop start button each time I enter the Jeep I noticed a couple weeks ago it wasn't working. To keep this short I replaced both batteries with the Genesis Offroad Gen 3 JL Dual Battery Kit. Tested the small battery and at 3 years old it was at 20% capacity. It tells me if you are keeping the small battery it should be replaced every 2 years. Installation of the dual battery kit went well. All of my dash lights are clearer and brighter and I feel confident I will always have the battery power needed.

 

[ForeOSU]

For those that did the bypass of the aux battery, did your “a!” Warning light eventually go away? I did the bypass last night but the warning light is still on as of my drive home from work today.

 

[Ang1Sgt]

I changed both Batteries on my 2020 V6 yesterday. With all the talk here on the forum about short life batteries from Jeep, I decided to pull the plug and do both at the same time. The two issues I had went away with the battery change.

I also pulled the block out of the battery well and went from an H6 battery to an H7 battery with much more Cold Cranking Amps to help combat the cold and the long time mine sits unused especially in the Winter Months.

 

[Nvdardx28]

For those that did the bypass of the aux battery, did your “a!” Warning light eventually go away? I did the bypass last night but the warning light is still on as of my drive home from work today.

That warning light will not go off as it thinks your AUX battery is dead.

 

[Rhinebeck01]

That warning light will not go off as it thinks your AUX battery is dead.

@Nvdardx28

Are you of the belief that if you do an Aux battery bypass (either of the 2 ways to do so) that you will always have a "warning light" / the ESS related "A"warning, because the JL thinks it's Aux battery is dead.. IF that is your thinking you are incorrect.

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