Main vs Aux battery replacement question on 2021 JT

[ecidiego]

The Aux will charge without disconnecting anything. Testing it is another story obviously. I charge through the 7 pin and afterwards... my start stop works every single stop for days. Eventually it starts not doing that as the alternator never 'finishes the job' since Jeep has it cutout too early.

After a 7 hr road trip I pulled the cables and the main was at 12.4. Ctek takes it to 12.8 like it should.

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[Mojave2021]

Thanks - trying to charge both batteries now and it’s taking much longer than when I was charging the main directly. Sounds like for the load test I need to remove it to test it. I should make sure I have a replacement on hand I guess if it fails so I don’t have to rip it out again (or I just replace it no matter what it reads if I go thru that work.

Anyways I’ll drive it a bit to see if it works better after fully charging both.

 

[Mojave2021]

Did the IBS reset procedure right after charging it up. Stop start now is enabled about 2 minutes after the truck warms up. Seems to be working much better now.

 

[Mojave2021]

FYI my aux battery wasn’t holding its charge overnight at all. The main battery was dropping overnight though not as badly as the aux was.

I tried replacing the aux battery alone and ESS worked the same day but then the next day it stopped working again. Once the main battery was replaced everything worked perfectly the next day.

I went with the larger Duralast Platinum Elite 94R battery from Autozone with a 5 year warranty and a Duracell Aux 14 with a 3 year from Batteries Plus. The 94R fit perfectly fine.

Replacing the aux battery from underneath was substantially easier than I was expecting it to be. Just removed a few clips on the inner fender closest to the battery and one bolt, folded the inner fender back and didn’t even need to remove the wheel/tire. Just turned it towards the driver side.

I did buy the aux battery initially from Summit Racing and they sent me a battery manufactured over 3 years back. I managed to get my money back after a very long conversation with one of their support managers. Now I know not to buy a battery online. The 2 batteries I ended up with were manufactured in the past few months.

 

[ecidiego]

I got that Duracell Aux. So far so good. Odyssey main. Odyssey should modify their Aux to fit properly. I tried... didn't want to 'make it work'. It's the plastic casting.

Main, even matches the paint. =D

 

[ecidiego]

The green LED is an ultrasonic emitter with white strobe.... added that after I found mouse shit on my battery. So far so good. I also spray peppermint oil all over the engine compartment and the suspension.

 

[ShadowsPapa]

I also spray peppermint oil all over the engine compartment and the suspension.

That's the only thing I found that actually worked keeping mice out of the WJ I had. Nothing else worked, then I saw a video where they actually tested it with real mice - gave it a try.
No further damage.
I did have to refresh it now and then, though.

I have to leave the hood up on my JD lawn tractor if I park it out under my lean-to. Dang rodents will find the top of the air filter by all of the console wiring within a day otherwise. Open, they don't bother it.

 

[ecidiego]

That's the only thing I found that actually worked keeping mice out of the WJ I had. Nothing else worked, then I saw a video where they actually tested it with real mice - gave it a try.
No further damage.
I did have to refresh it now and then, though.

I have to leave the hood up on my JD lawn tractor if I park it out under my lean-to. Dang rodents will find the top of the air filter by all of the console wiring within a day otherwise. Open, they don't bother it.

I don't know if the ultrasound plus strobe thing even works but I'm leaving it.... belt and suspenders approach. It's another battery drain tho.

 

[Mojave2021]

I got that Duracell Aux. So far so good. Odyssey main. Odyssey should modify their Aux to fit properly. I tried... didn't want to 'make it work'. It's the plastic casting.

Main, even matches the paint. =D

Yeah the Duracell fit perfectly. I have an Odyssey in my 77 Trans Am and it has been great. But I decided to go with the Autozone one on the main battery as it had a 2 year longer warranty, and the specs look pretty similar to the Odyssey. With the Autozone 2 minutes from our house I thought it made sense and it's substantially cheaper.

 

[Mojave2021]

ESS has been working perfectly for a few weeks now. You guys were right that the voltage definitely varies a lot more now with healthy batteries. I expected the drop when turning off but not the variation when on. Never had this type of system on a car before.

Gas mileage is up about 1 to 1.5MPG after.

 

[JTSUSN]

Thanks guys for the quick responses!

I’m new to the forum and I have a question about replacing both batteries. It may be a little drawn out but I want to get the full context in here. I had been having a slow to start problem and had to jump it off a couple times. The last time I got this message I had never seen before saying to safely stop the vehicle was shutting down, I was already stopped so I tried again but the battery seemed like it was charged enough after testing so I wanted to see if it was the alternator, I loosened the positive terminal started it back and removed the terminal, it shut off ( old school thinking it was the alternator).I replaced it , then COMPLETELY dead no lights, dings… nothing. Now today I replaced both batteries, it started then those crazy messages, vehicle not in park , wipers coming on I mean like it’s possessed. Now it will not even move and I’m about ready to put a match to it. Any suggestions?

 

[ShadowsPapa]

but the battery seemed like it was charged enough after testing so I wanted to see if it was the alternator, I loosened the positive terminal started it back and removed the terminal, it shut off ( old school thinking it was the alternator).I replaced it

No, don't ever do that. It's not a way to test, it's a way to blow things up.
Never ever do that to ANY alternator, old or new type. That's left over from your great grandfather and GENERATORS. A generator is ok, but an alternator - you can lead to voltage spikes that blow things out like diodes and worse.
You can blow the alternator, the regulation circuit and other things due to voltage spikes. I've seen diodes blown apart by that.

Anyone looking on, never disconnect a battery cable to "test" an alternator - it's a good way to lead to some very expensive repairs!

Now, the fact that yours died suggests to me that the aux battery was bad or at least dead. you have two batteries.

First, some questions - you CHARGE both new batteries before replacing them?
Did you disconnect the IBS that sits on the main battery negative terminal from that small connector while it was off to reset it?
Rules - when replacing batteries, ALWAYS fully charge the replacements before installation.
When replacing the batteries in a vehicle with the IBS on the negative clamp, disconnect the IBS connector for at least 20-30 seconds while it's off the battery to reset it for relearning the new batteries.

When you had the main battery out, were you very careful to not let the positive cable touch ANYTHING at all - since the aux battery would keep the system hot and you could blow high current fuses that way......

You may have either blown the high current N3 fuse, or caused some other issues.

I was already stopped so I tried again but the battery seemed like it was charged enough after testing so I wanted to see if it was the alternator,

What does it mean - "charged enough after testing" - who tested the batteries and how? (hopefully not a parts store)

You'll need to perhaps back things off- disconnect both batteries, isolate them, make sure they are both fully charged with a good AGM charger, (these are AGM batteries), and check your high current fuses at the end of the fuse box -

This is the IBS -

Only ever charge a battery that's in the vehicle with the charger connected inside the green circle, never where the red X is.

This is the high current fuse - you very possibly blew out N3 on this -

To be very blunt -
whoever said it's ok or even a way to test an alternator by pulling a battery cable is - well, they'll never ever touch anything I ever own. They are causing more trouble that fixing. Not only is it a horrible idea, most of the tech books on alternators say never to do it.

 

[JTSUSN]

Thank you very much for all of the info, I’m definitely not used to all this high tech, computer technology in newer vehicles. I have never had to charge a battery after buying it and this is my very first time dealing with two at the same time. I will definitely try disconnecting and reconnect with the IBS sensor disconnected. I spoke to a buddy that had the same issue after replacing both batteries in a JL, he said he was able to get it to a shop and reset the codes and everything was fine after that

 

[ShadowsPapa]

Thank you very much for all of the info, I’m definitely not used to all this high tech, computer technology in newer vehicles. I have never had to charge a battery after buying it and this is my very first time dealing with two at the same time. I will definitely try disconnecting and reconnect with the IBS sensor disconnected. I spoke to a buddy that had the same issue after replacing both batteries in a JL, he said he was able to get it to a shop and reset the codes and everything was fine after that

And it might be fine after resetting - possible the codes were there as a result of the earlier issues and won't come back

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