Battery Charging

[Lost1wing]

If you only have the battery charging message on the ess page like me. Charging both batteries and resetting the ibs got the message to go away and the ess to start working again.

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[rr11]

It started working but within 48 hours it was back to battery charging.

 

[Lost1wing]

It started working but within 48 hours it was back to battery charging.

You can isolate them again the see the voltages independantly. Let them sit for a while then check again. Maybe your Aux battery is going south, as was said in other posts, not all parts store test batteries correctly.

 

[rr11]

I agree on parts stores checking batteries, but this test was by the owner and has been doing test for years. I will try bypassing the aux and see how it acts.

 

[Lost1wing]

I agree on parts stores checking batteries, but this test was by the owner and has been doing test for years. I will try bypassing the aux and see how it acts.

With both batteries paralleled together, you just won't know who the culprit is. The best way in my opinion would be to disconnect both charging them both with an AGM charger. Let then sit isolated over night and put the meter on them to see which one is not holding a charge. A good battery that passes a load test doesn't mean it is fully charged.

 

[Lunentucker]

On a 2020 which of the neg wires on the main battery terminal is the aux neg?

2020 should be the smaller diameter cable. For whatever reason they flipped them in 21.

 

[Lost1wing]

2020 should be the smaller diameter cable. For whatever reason they flipped them in 21.

Funny you say that. That is what I thought. I also read somewhere that the M8 stud is for the supplemental battery and the M6 stud is for the fender ground. I need to physically look at mine. Mine is a 2020.

 

[rr11]

I checked the grounds using Shadows Papa's instructions. on my 2020 build date it was the cable on the taller stud.

 

[tonywin]

I removed the AUX negative cable from the main battery post, taped and it up, and removed fuse 42. That should be enough to isolate the auxiliary correct?

Is it normal for the service stop start battery light to come on?

 

[ShadowsPapa]

System is ready 30 miles in I hit my first stop light and when the engine stops the voltage drops from 14.1 to 12.2 is this normal.

How fast does it drop?
If it takes 30 seconds, it's NORMAL as it's under load.

If it's there instantly, then it's a problem. If it takes a few seconds, it's FINE.

 

[ShadowsPapa]

, but this test was by the owner and has been doing test for years.

Doesn't mean he's ever done them correctly. You can NOT properly check or test a battery if it comes in to be tested at under about 12.4 volts. It needs to be charged, then tested. Testing a low battery is, well................

There are multiple things to look for - capacity and cranking amps.
CCA is a spring, capacity is a marathon. A battery can pass CCA type testing all day and fail in the longer run. Or it can supply decent power over time, but not a heavy draw for a short period.

I removed the AUX negative cable from the main battery post, taped and it up, and removed fuse 42. That should be enough to isolate the auxiliary correct?

Is it normal for the service stop start battery light to come on?

No.


This pic shows charging only the aux battery, on a 2020.
For 2021, the cable with the larger end that has the stud is the aux battery ground.
In the case of the 2020, the top ground cable is the aux battery ground cable.
2021 and later the top ground cable is the chassis ground cable.
They hire an engineer to change how cables connect every couple of years.
I think he's the same guy that used to figure out where the hood release cable handle went on the next model year.


Anyway - picture below, charging the aux battery on a 2020.
Positive charger clamp on the positive cable clamp on the main battery, charger negative clamp on the aux battery cable end.

 

[tonywin]

No.


This pic shows charging only the aux battery, on a 2020.
For 2021, the cable with the larger end that has the stud is the aux battery ground.
In the case of the 2020, the top ground cable is the aux battery ground cable.
2021 and later the top ground cable is the chassis ground cable.
They hire an engineer to change how cables connect every couple of years.
I think he's the same guy that used to figure out where the hood release cable handle went on the next model year.


Anyway - picture below, charging the aux battery on a 2020.
Positive charger clamp on the positive cable clamp on the main battery, charger negative clamp on the aux battery cable end.

Thanks for the picture. I have a 2020 and I removed the cable that has the negative clamp on in your picture. Is there an additional step I need to do?

 

[Andy29847]

I removed the crank battery and had NAPA test it and they said it was good. This leads me to believe the aux battery is bad. I guess my next move is to pull the fuse and the aux negative.

This doesn't mean much. The Jeep systems are setup with unusually high thresholds. A battery that tests good might not be good enough to pass the Jeep poll for the stop/start system. That is one reason it often takes multiple visits to get battery problems fixed. I think that if you disconnected your aux battery and you are still getting a similar message from your Jeep, that is a strong indicator of problems with the main battery.

If you decide to replace the main battery, go for something like this:

MTX-94R/H7 battery | Interstate Batteries

850 cold cranking amps, 140 minutes reserve capacity, 36 month warranty

 

[rr11]

Prior to testing the battery I placed a Noco 10 battery charger/maintainer on the positive terminal and the tall stud on the IBS for 24 hours. The charger showed the system at full charge and I removed the battery from the jeep to test it.

 

[kahuna357]

Mine never says anything about battery charging, it only says START/STOP not ready. The weird thing is it works normal if the outside temp is at least 50F. Below that temperture START/STOP not ready.

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