Start stop not ready / battery charging message after aux battery change - What next?

[ATX_Jeeper]

My new to me 21 JTRD always has this message on. Today I replaced the Aux battery and still see the message even after a short test drive. During the drive I did notice the voltage fluctuating between 12 and 14 volts. Once I got home I used my volt meter to test the original aux battery since it was now out of the Jeep and it was reading about 12.3 volts. I also tested the main battery with the engine off and it was also reading 12.3 volts. Unfortunately I did not test the new aux battery before installing it but it had a date code of 12/22 so I'm sure it was fine.

What other options do I have to resolve this issue?

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[Lunentucker]

I'd put it in charge overnight and give it a few run cycles to see if it clears.
I think you're going to get equal voltage readings as long as they're connected in the factory default configuration.
You might also try pulling the ESS fuse and running it for a bit with that out.

F42 is the one.

 

[ATX_Jeeper]

I'd put it in charge overnight and give it a few run cycles to see if it clears.
I think you're going to get equal voltage readings as long as they're connected in the factory default configuration.
You might also try pulling the ESS fuse and running it for a bit with that out.

F42 is the one.

I usually have ESS disabled and the Tazer remembers that setting so I'm not worried about being stranded and just wanted to clear the error message. Also, when I tested the original aux battery it was out after the Jeep and after the test drive. I guess I was expecting it to be dead to let me know the new aux battery just needs some run time to top off. Hopefully this clears up after a few more drives but for now, its bugging me.

 

[Lunentucker]

I usually have ESS disabled and the Tazer remembers that setting so I'm not worried about being stranded and just wanted to clear the error message. Also, when I tested the original aux battery it was out after the Jeep and after the test drive. I guess I was expecting it to be dead to let me know the new aux battery just needs some run time to top off. Hopefully this clears up after a few more drives but for now, its bugging me.

So you're getting this message with ESS disabled?

 

[ATX_Jeeper]

So you're getting this message with ESS disabled?

No, I have to enable it. I usually have it off so that I don't see the ESS message and won't get stranded at a stop light.

 

[Jeeperjamie]

It either needs time to recharge or your main battery was the problem instead of your Aux Battery. I had the same thing going on and ended up taking mine tot the dealership and I thought it was the small aux battery and they hooked it up to the machine and said the bigger battery had a dead cell and was the problem. Had it replaced and haven't had anymore issues. It took about 50 miles of driving for the ESS/Aux battery to recharge and start working again.

For reference I took mine to Advance auto and tested it myself and both my test and advance's test showed the Main battery being fine but the machine at the dealership said something different. They told me that people come in all the time with the same issue I was having saying it's the small battery and saying they took it to advance or tested it at the house and it seemed fine only to find out once they put it on the machine that it was the main battery the whole time.

 

[Jeep-A-Kneez]

I found that the message you are getting " start/stop not ready, battery charging" is about the main battery. If the auxiliary battery is bad then you will only see "start/stop not ready". Of course this is provided all other requirements have been met to allow the start/stop to operate, steering wheel turned, not at operating temperature are a few.

 

[ATX_Jeeper]

It either needs time to recharge or your main battery was the problem instead of your Aux Battery. I had the same thing going on and ended up taking mine tot the dealership and I thought it was the small aux battery and they hooked it up to the machine and said the bigger battery had a dead cell and was the problem. Had it replaced and haven't had anymore issues. It took about 50 miles of driving for the ESS/Aux battery to recharge and start working again

Thanks for this info as I was wondering if the main battery could also cause the message. Next time I'm out I'll have the local parts store test the main battery. If its bad, I'll try to get the dealer to replace it.

 

[Jeeperjamie]

Thanks for this info as I was wondering if the main battery could also cause the message. Next time I'm out I'll have the local parts store test the main battery. If its bad, I'll try to get the dealer to replace it.

I had Advance check mine and they said it was good to go. I took it to the dealership and was expecting them to just replace the small battery but they said they had to test the system first. When they threw it on the machine, it came back that it was the main battery. I'm not sure what the difference is but my guy at the dealership showed me the read out and it was a dead cell in the main battery.

 

[ShadowsPapa]

My new to me 21 JTRD always has this message on. Today I replaced the Aux battery and still see the message even after a short test drive. During the drive I did notice the voltage fluctuating between 12 and 14 volts. Once I got home I used my volt meter to test the original aux battery since it was now out of the Jeep and it was reading about 12.3 volts. I also tested the main battery with the engine off and it was also reading 12.3 volts. Unfortunately I did not test the new aux battery before installing it but it had a date code of 12/22 so I'm sure it was fine.

What other options do I have to resolve this issue?

Did you remove the IBS for several minutes to reset it?
Did you use an AGM charger and fully charge the new battery before installation?
Did you also fully charge the crank battery?
(best to do all three of the above)

I found that the message you are getting " start/stop not ready, battery charging" is about the main battery. If the auxiliary battery is bad then you will only see "start/stop not ready". Of course this is provided all other requirements have been met to allow the start/stop to operate, steering wheel turned, not at operating temperature are a few.

While the truck is sitting in your garage and while you are driving it, the batteries are in parallel - connected together.
It only knows about the crank battery via the IBS and if the battery has been charged improperly, it can't have valid information about the crank battery.
The only time it knows about the aux battery is at the instant you push the big button to start it.
Once started, they are together.
My 2020 used to give me the not ready, battery charging message until I had driven long enough to charge the batteries. Neither battery was bad. It just sat long enough the voltage was low (below 12.4)
Once I'd drive it long enough, then that not ready, battery charging message went away.
So - how would it know which was which since they are connected together the whole time you are driving?

Thanks for this info as I was wondering if the main battery could also cause the message. Next time I'm out I'll have the local parts store test the main battery. If its bad, I'll try to get the dealer to replace it.

I'd not let the fools at a parts store test a lawn mower battery.
You can't test them properly until they are fully charged with a correct charger, which may take a couple hours - up to 3 or 4 hours. Those clowns and their hand held test tools are a joke, IMO.

 

[ATX_Jeeper]

I had Advance check mine and they said it was good to go. I took it to the dealership and was expecting them to just replace the small battery but they said they had to test the system first. When they threw it on the machine, it came back that it was the main battery. I'm not sure what the difference is but my guy at the dealership showed me the read out and it was a dead cell in the main battery.

I was hoping to avoid the dealer for now.

 

[ShadowsPapa]

I had Advance check mine and they said it was good to go. I took it to the dealership and was expecting them to just replace the small battery but they said they had to test the system first. When they threw it on the machine, it came back that it was the main battery. I'm not sure what the difference is but my guy at the dealership showed me the read out and it was a dead cell in the main battery.

No parts store CORRECTLY checks batteries. They are clowns with amateur tools and no training.
You can't throw a load on a battery and say good or bad unless it's REALLY bad.
The dealer has a procedure that it more correct - if the voltage is under something like 12.4 volts, they must charge the battery first. A 12.4 volt battery is almost HALF DEAD. So how can you properly check a half dead battery?
Fully charge battery with correct charger, sometimes taking hours.
THEN test it.
Heck, parts stores sell parts - drive in with a battery at 12.2 volts, they toss a load on it and it fails, oops, you need a battery. Congrats, you just tested a battery that's less than half charged and it failed.

 

[Jeeperjamie]

No parts store CORRECTLY checks batteries. They are clowns with amateur tools and no training.
You can't throw a load on a battery and say good or bad unless it's REALLY bad.
The dealer has a procedure that it more correct - if the voltage is under something like 12.4 volts, they must charge the battery first. A 12.4 volt battery is almost HALF DEAD. So how can you properly check a half dead battery?
Fully charge battery with correct charger, sometimes taking hours.
THEN test it.
Heck, parts stores sell parts - drive in with a battery at 12.2 volts, they toss a load on it and it fails, oops, you need a battery. Congrats, you just tested a battery that's less than half charged and it failed.

100% correct. The guy I deal with at my dealership told me the same thing. It cost me $86 for them to test it right but they knocked it off the price of the main battery they installed. Worthy it for peace of mind as far as I'm concerned.

 

[ATX_Jeeper]

Did you remove the IBS for several minutes to reset it?
Did you use an AGM charger and fully charge the new battery before installation?
Did you also fully charge the crank battery?
(best to do all three of the above)



While the truck is sitting in your garage and while you are driving it, the batteries are in parallel - connected together.
It only knows about the crank battery via the IBS and if the battery has been charged improperly, it can't have valid information about the crank battery.
The only time it knows about the aux battery is at the instant you push the big button to start it.
Once started, they are together.
My 2020 used to give me the not ready, battery charging message until I had driven long enough to charge the batteries. Neither battery was bad. It just sat long enough the voltage was low (below 12.4)
Once I'd drive it long enough, then that not ready, battery charging message went away.
So - how would it know which was which since they are connected together the whole time you are driving?



I'd not let the fools at a parts store test a lawn mower battery.
You can't test them properly until they are fully charged with a correct charger, which may take a couple hours - up to 3 or 4 hours. Those clowns and their hand held test tools are a joke, IMO.

I believe the IBS is connected to one of the battery terminals. If so, both batteries were removed for the aux battery install. The main was out for about 10 min and the aux was out for about 5 min.

The new aux battery wasn't touched prior to install.

The main battery wasn't tested or charged. It was just removed and re-installed as the aux battery sits underneath it on the diesel models.

I was only going to let the parts store test the main battery since it is easily accessible. Fair point about them being clowns though. I do have a battery tender so I have the ability to charge the main battery if I need to. However, if its going bad, I'll just replace it.

 

[Jeeperjamie]

I was hoping to avoid the dealer for now.

That was what gave me peace of mind. You might can find a shop with a similar setup.

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