Aux battery issue diagnosis

[Frenzyrider]

I am trying to isolate my issues with aux battery and I do want to keep it so not interested in Aux battery delete options. I have read through all the threads on this including expert recos from @ShadowsPapa - Thank you! Your posts are awesome on this topic.

2021 JT Rubicon
57000 miles
Replaced Aux battery with Duralast and primary with Oddysey about 3 month ago.
One month after the replacement, I was on a trip towing a trailer. In the morning at camp, Jeep was dead. Wouldn't crank. One thing to note is I had done undercarriage cleaning before the trip so its possible some water went to aux battery but not sure. Anways, somehow got it to jump start and get back home. Took the batteries out.. Primary was in good shape and I fully charged it. Also, took the aux battery out and fully charged it. No issues again.

Until yesterday, my jeep went dead when it was parked at a parking lot. Another coincidence was I had washed the interior of the hood but had covered the primary and alternator so no water went there. However, forgot about the aux and suspect that some water may have run into it by the wiring from primary.
Anyways, got it to jump start. Brought it home and trickle charged the whole setup by connecting the negative to IBS and positive to the positive terminal of the primary. After 5 hours of it, it seems to be the Jeep is started again this morning.

My suspicion is perhaps water or something I did when i replaced the battery caused it. As next steps I am thinking of checking whether my Z case fuse array has the N3 blown which may lead to aux battery not charging from the alternator. However, it gets charged when I hook up the maintainer or the jump starter to the primary? Possible?
And does the 7 pin of the trailer wiring power from aux battery because that can also explain my aux battery getting drained as it is not getting power from the alternator perhaps?

Sponsored

 

[Lunentucker]

Always a smart move to double your chances of failure!
Good luck to you!

 

[Frenzyrider]

Always a smart move to double your chances of failure!
Good luck to you!

I wouldn’t have suspected water until the second time it happened and even then it is a coincidence that is drawing me to that conclusion.

 

[sharpsicle]

Always a smart move to double your chances of failure!
Good luck to you!

Wow, talk about a tone-deaf reply.....

As for OP, the 7-pin harness is just wired into the electrical system like everything else. That whole system is going to be powered by both batteries in all situations except ESS events.

I wouldn't suspect water to be the issue as much as a parasitic drain somewhere that shouldn't be. I suppose it's possible the water shorted something out, which is now causing a drain, but it really sounds like you have a power drain somewhere that needs to be identified and remedied.

If your AUX was never receiving a charge, you'd be getting messages related to it on your EVIC Auto-Start Stop page. After you charge everything up, does ESS work?

 

[Frenzyrider]

Wow, talk about a tone-deaf reply.....

As for OP, the 7-pin harness is just wired into the electrical system like everything else. That whole system is going to be powered by both batteries in all situations except ESS events.

I wouldn't suspect water to be the issue as much as a parasitic drain somewhere that shouldn't be. I suppose it's possible the water shorted something out, which is now causing a drain, but it really sounds like you have a power drain somewhere that needs to be identified and remedied.

Very helpful. I took out all my accessory connections the first time it happened.
I will pull the fuse array but I am wondering whether the battery can be charged with jump if N3 is blown. Meanwhile I will battery tender it before trips.

 

[sharpsicle]

Very helpful. I took out all my accessory connections the first time it happened.
I will pull the fuse array but I am wondering whether the battery can be charged with jump if N3 is blown. Meanwhile I will battery tender it before trips.

Is N3 blown? It's easy enough to check, and it'd probably be faster to do that than anything else.

If your crank battery is getting low and won't start, N3 being blown wouldn't really have anything to do with that.

 

[Frenzyrider]

Is N3 blown? It's easy enough to check, and it'd probably be faster to do that than anything else.

If your crank battery is getting low and won't start, N3 being blown wouldn't really have anything to do with that.

So this thread in the wrangler forum is my suspicion which is a blown N3 will likely still make things work but the aux battery will just deplete power without getting charged by the alternator and main battery. And at some point it will get discharged. When you jump the car it gets the power through N1 to charge it enough to start. https://www.jlwranglerforums.com/fo...-cable-caution-and-ess-n3-fuse-warning.66247/
Will check the fuse next.

 

[Frenzyrider]

Alright. So the z case fuse array is good with all fuses but I ordered one anyway for the trail since people have mentioned that it can be an issue in future. Now I will likely take the aux battery out and see if there are no issues there.
Saw Genesis is making this relocation kit for aux battery. I might take it up later. For now I will check the battery and try going through the wheel well instead of the fuse box to make sure there is nothing there.


https://www.genesisoffroad.com/2018-jeep-jl-stock-battery-relocation-kit.html

 

[Mr._Bill]

Alright. So the z case fuse array is good with all fuses but I ordered one anyway for the trail since people have mentioned that it can be an issue in future. Now I will likely take the aux battery out and see if there are no issues there.
Saw Genesis is making this relocation kit for aux battery. I might take it up later. For now I will check the battery and try going through the wheel well instead of the fuse box to make sure there is nothing there.


https://www.genesisoffroad.com/2018-jeep-jl-stock-battery-relocation-kit.html

That's nice and all, but under typical conditions the Aux Battery only needs accessed once every three years. The bracket also moves it up into the heat. The fender liner has enough flex that it can be bent back to change the battery without removing the liner.

 

[Frenzyrider]

That's nice and all, but under typical conditions the Aux Battery only needs accessed once every three years. The bracket also moves it up into the heat. The fender liner has enough flex that it can be bent back to change the battery without removing the liner.

Yeah! It’s a lot of work to relocate. I can upgrade my fender liner to AAL and have the quick release feature that will look good as well. I have done it with bending the plastic. Removing is easy but bolting it back up was a chore. May be I will use a piece of wood with a bottle jack next time to move it up.

 

[Frenzyrider]

So I did two tests of the aux battery. One with isolating the negative terminal at the primary as has been documented well here and connecting the positive of the primary. The aux battery showed poor health but full charge.

This made me pull out the aux battery and did another test with no cables and directly on the aux battery in my garage and it shows full health and charge.

Now I am super confused because this is a 3 month battery and clearly Autozone won't replace it because it will show full health and charge. I am wondering if a loose cable can show poor health in the earlier picture. Any clues anyone?

The bright side is i am now super efficient in pulling the aux battery. No tire or fender removal needed and I just bend the plastic to take it out.

 

[Mr._Bill]

Loose cables can definitely cause problems. Make sure the little posts are tight that had to be transferred between the Aux batteries.

Separating the cables is good for checking voltage and charging. I'm not sure it's a big enough Guage to handle load testing the Aux battery.

 

[Frenzyrider]

Thank you @Mr._Bill
Autozone replaced it because their tester wasn’t working. So I am now going to trickle charge it over several hours that I hadn’t done last time when I got the aux battery thinki it is new. Learnings! Let’s see how it goes this time. Will keep this thread updated. I tightened up the stud at the terminals as well so they are snug tight.

 

[Frenzyrider]

Fully trickle charged the replaced aux battery and we are good so far. One more thing I noted which may be helpful for some. If you have Sirius XM then you will see the genre and artist name in blue if the aux battery has issues vs. in red if your battery system is in good shape.

PS: Don't judge my songs. I listen to everything that has a beat.

 

[Gatorized]

Fully trickle charged the replaced aux battery and we are good so far. One more thing I noted which may be helpful for some. If you have Sirius XM then you will see the genre and artist name in blue if the aux battery has issues vs. in red if your battery system is in good shape.

PS: Don't judge my songs. I listen to everything that has a beat.

That seems random - although the nav and phone icons changed colors too.

Sponsored