Hey Nightshadow, is this what you are experiencing...?
See video below

 

Mine did just like this in my 2013 xj

 

Are you still having this issue?

 

Dude, that is EXACTLY what happens to mine. Exactly. Have you fixed it yet?

 

*Finally* uploaded 2 videos of my experience guys. I am really hopeful that, despite what people have said on here, somehow replacing that auxiliary battery makes this problem go away - although I'm fairly certain it won't as many of you it sounds like have been driving without one and not having this issue.

 

I have been driving for over three years now with the secondary battery disconnected and not a single electrical problem ever.

 

I know it sounds weird but I'm thinking it's the headlight stalk/switch failing that is the issue you guys are experiencing.We have had previous threads with dash and headlights flickering and the solution was replacing the switch/stalk. Just my take.

 

Hey Nightshadow,

Your experience in the video, was the exact same as my experience. It scared the sh@t out of me! It happened to me several times while driving. We both have 2013 models as well. I replaced the small auxillery battery and the start/stop battery as that function has stopped working as well. The auxillery battery was purchased used off of eBay for about $50. The start/stop battery was about $200 from the dealer. I installed them both myself at the same time and I have never had that problem again. Maybe others have a different solution. I can tell you from personal experience that that’s how I resolved the issue. I hope this helps brother.

 

Replacement of the headlight stalk solves a different problem (flickering of headlights and flickering of intensity of interior/ dash lights). This video shows something very different. Hope you figure it out.

All the best.

 

There’s a difference between the auxillery battery and the secondary start/stop battery. They’re not the same. You can drive perfectly fine without the start/stop battery. You simply will not have that function. The auxillery battery is located in the trunk on the right hand side, behind the carpet. I believe the proper name is the battery converter module. It’s commonly refered to as the auxillery battery though. The start/stop battery is co-located with the spare tire. But no worries. Just trying to clear up any confusion.

 

Hey all - just thought I'd update. Although I do agree with some of the members on here that the "Eco Start" feature is a complete waste and it annoys me to no end (sometimes I forget to turn it off) - I have not had this problem again since October and it's now March. So I would consider this issue resolved with regards to the electrical. I wanted to wait some time before posting to see if it was just temporarily fixed or truly fixed, so yeah, 6 months later here we are.