Went out for a few.
Had a great time.
Started the car and had the large Jaguar logo.
Bit chilly so went to crank the heat.
Buttons work, but screen stayed the large Jaguar logo the whole way home.
Pressed Home, Power, nothing reacted.

My plan was to see what it did in the morning, but figured I’d post here.

Thoughts?

 

Hey, as per the workshop manual there is a procedure to follow for troubleshooting these issues. And the electrical pinpoint tests ALWAYS start with confirm the health of the electric source.

There are a few common problems should electrical power fall below limits. The screen and epb to name the first tell tales.
Recall electrical power is a product of voltage and amperage. The battery is an integral part of the solution. The generator without a healthy battery cannot “fuel” these systems.

 

Mine was the same.


8 year old battery

 

As mentioned earlier, for our cars, first place to look at is battery. Replace with the most recent manufacturer's date possible. I like walmart because they have a good turn around with new batteries regularly. Good luck.

 

Ok, phew.
No idea what happened last night that stuck it on the Jag splash screen, but just went out and started her.
screen worked fine. Battery at 13.4v.

Will monitor.

 

Sorry to be the bearer of bad news. I HIGHLY doubt your battery's resting voltage is 13.4v.

 

Well put me in a dress and call me Sally.

Yeah. I only look while she is running.

Using my OBD app:

👇 Engine running:


👇 Start button no brake:


She starts with zero hesitation, but I’m gonna guess it is time to grab that CTek.
Then if she doesn’t recondition, replace the battery before gremlins start popping up.

 

Now "she's" talking good sense ;-)

 

Your battery at rest with cables detached should read as close to 12.66 as possible. When I go to purchase a new battery at walmart, I always bring my voltmeter with me. Between a recent manufacturer's date and the highest reading 12.66+ I make my decision. Then I politely ask someone (related to Arnold Schwarznegger) to help put the 70lb monster in the trunk of my car.

 

Probably the biggest pitfall of a convertible.
10x more difficult to get a battery out and new one in.
Especially when one is 6’3 190.
Cant wait for that fun chore.
I’ll go ahead and schedule the chiropractor and massage therapist now.

Boca, mind sharing the make/model you buy from Wally World? Probably the best bargain.

 

When I changed my battery last year, it was much easier than I expected, as long as you prepare first. I think @Cee Jay has posted about it before. Use a 2x6 or such to make ramp to slide the sucker up and out, then slide the new one back in.

 

Walmart. Everstart. Size: H8. Flooded Type. Non AGM Keep mine on a CTEK every single night regardless of daily use. This one is 3 1/2 years old. 3 years is about average life for a Florida battery. Im on my 3rd or 4th battery in about 13 years. Keep that baby fresh!
PS. I will never attempt to install the battery myself and I have a Coupe. It’s a feat to move it around!

 

 

I remove the spare tyre, get the battery into the trunk, then stand in the trunk and position the battery in place. I'm small(ish...) so can get away with this scheme. Neighbours know I'm crazy anyway, so it's a good show for them...

 

@Circumnavigator , like bocatrip, I purchased a Walmart battery - except mine is an AGM. I thought an AGM would better handle any power drain from the car's electronics. Here are details if you want to go that route.
...
I chose the boxed one shipped directly to my home as I thought it would be freshest. I ordered it on January 27, 2025, and the manufactured date on the battery was November 2024, so it was less than three-months old.
Your X150 would have come originally with a Varta battery. Here are Varta's battery specs for your X150 (link) showing the same size case, but the EverStart has more cold-cranking amps (CCA).
Be sure to keep/use the vent-hole plug that comes attached to the red-plastic cover over the positive terminal. And fully charge it before installing.

 

Just ordered the CTek MXS 5.0, an 8’ cable and the proper M8 eyelets connector.
(Heads up, it comes with the M10)
Almost the price of a battery lol but kind of a necessity with the XKs.
Ran a long extension cord along the wall, took a look at the space in the trunk behind the cover where I will connect it permanently and set out the sockets for each nut, pos and neg.
Now we want patiently until Monday for delivery.

While I had that cover off, I did run my multimeter between the +/- in there and got 12.35v after sitting all night.
So here’s to hoping a cycle on reconditioning will bring it back to par and buy me some time.

 

Feel.like the medical bills were higher than the 50 bucks my indy charged me to install

 

Raise the "hood" (convertible top) mid-way with the tonneau cover open, prop the hood and tonneau and turn off the ignition.
Easy access to all things under the trim cover, including the battery.
I will admit that the 70-pound battery gets heavier each year. (That's what a son-in-law is for! )

 

Circumnavigator....Your 12.35 resting volts after sitting all night reveals the battery is between 50-70% of it's total charge. Our batteries are the heart of out electrical systems and need to be as close to 100% as possible to avoid glitches which are many on our cars. Also, NEVER run the battery down as this can sometimes just kill the battery without the potential of bringing it back to life. Having the maintainer is a good start, but it won't revive a weak battery. If it were me, (but I don't want to spend your money), I'd bite the bullet and just get the freshest battery you can and this way you have a great starting point. It's not a good idea to be chintzy when it comes to an XK battery. We already have a temperamental electrical system.

 

Noted and appreciate the input.
I fully expect to replace the battery, but will do a bit of research first on wet and AGM options.

In the interim, I want to play around, experiment and learn.
So after having tons of lights on and installing the LEDs which took about an hour. (the car has sat since I took that 12.35 measurement Friday)
I just measured and it is at 11.99v.
Gonna go fire her up and take her for a nice 30m drive and measure when I get back.
Get some baseline numbers for before the Ctek shows up tmr.
Then I'll run the recondition and disconnect. And measure the drop over x days.
I have a backup vehicle, so not like I'll be stranded.
Again, just having some fun and learning.
Then of course, I will get a new battery, then some back surgery after it is in and I'll know what to look for going forward from experience.