Howdy folks, the time came with the cold weather that my '19 XJ started showing the low battery warning, even immediately after driving and shutting the car off, so I started searching here for help but couldn't seem to find everything in one place. Thus, here you go, what worked for me.

First of all, you will need a battery - the size and specs are basically size H8 12 Volt AGM type battery - 900 CCA minimum. Supposedly "Group 49" is equivalent, but in the USA I had no trouble finding an H8 battery at multiple stores, (despite all of their vehicle checks saying the battery would not fit). Posts here led me to Walmart - same day delivery!

Tools - you'll need a 10mm socket, a 12" extension, and a socket wrench.
Strength - these batteries weigh around 60 pounds, so if you can't lift that up and then down into a trunk well, consider paying someone to do it for you!
Time - From start to finish and getting all the equipment, it took me about 30 minutes - its really just four bolts, assuming you know what to do.
Frustration - The biggest hassle is the bottom retention bracket, which will require the extension, after you remove the positive lead from the battery.
Oddities - opening the trunk to begin, something was beeping softly, seemingly from the panel where the gas door is, on the side of the trunk. Eventually it stopped - no idea what that was about.

Removing:

- Before I started, I opened the hood and put a trickle-charger on the emergency lead, to keep from losing settings. Thankfully the 2019 model has the ground bolt close to a very simple positive connection, under a red plastic cap.
- Then, open the trunk, and move the floor liner out of the way - you can clip it up or just pull it out.
- Remove the plastic cover over the negative terminal.
- 10mm will get you the top retaining bracket bolt, so that's out of the way.
- 10mm again on the negative terminal first, then the positive - pull the wire assemblies back and tuck them out of the way. (I considered covering them to keep them from shorting against the car, but found good wedges with the spare tire.)
- 10mm with extension to get the second retention bracket bolt, that is under the negative wiring initially.
- Maybe - I didn't see one, but there maybe is another small clamp near the rear seats and the base of the battery that needs to be removed - I did not remove this, but pulled out and wedged in my battery (live and learn).
- Pull out the red-tipped gas evap hose from the side of the battery - this has a 90° bend and should just slot out.

Installing:

- Same as before, tilt the new battery and slide it in, ensuring it seats solidly - you don't want it rocking around.
- Maybe - re-tighten the clamp at the far end of the batter base.
- Plug the red-tipped gas evap hose into the side of the new battery.
- Re-install the bottom bracket and retaining bar, and then the top - ensure you have the battery seated properly!
- 10mm on the positive lead and tighten.
- 10mm on the negative lead.
- In my case, now I disconnect the trickle charger, replaced the plastic cover, and start the car - all normal and quick fire up!


All done, my seat settings and radio were fine, but a few things reset or needed to be set up again:
- The trunk close button - the car would just beep at me until I closed the trunk manually, and then re-opened it to test it again.
- The dash digital display - I needed to reset my gauge style.
- The rear windows - they needed to be re-trained for auto-up.

Hope it helps.

Threads that helped the most -
https://www.jaguarforums.com/forum/x...019-xj-265123/
https://www.jaguarforums.com/forum/x...cement-277852/

Also - window reset instructions, (copied from here at some point)

The windows will need to be reset if the battery is disconnected, becomes discharged or power
supply is interrupted. Once the power supply is restored, reset the windows as follows:

1. Close the window fully.
2. Release the switch, then lift it to the close position and hold for two seconds.
3. Open the window fully.
4. Release the switch, then push it to the open position and hold for two seconds.
5. Lift and release the switch to operate the one-touch function.
6. Repeat the procedure on each window.

 

I have a ‘15 convertible. and The biggest issue I have is getting the damn luggage barrier thing back in position.