Almost Dead Battery With Strange Occurance

[Freebird Paul]

Evening All,

My car is a 2006 XK 4.2 with an almost dead battery after returning to the car after 1 month away from the country. While attempting to open the car with the remote nothing happened just dead however i noticed the alarm red light on the facia was flashing. So I removed the key from the fob and pulled off the cover from the front passenger door and got into the car to find no door opening lights and no response from the button to open the boot. I then got into the boot via behind the number plate. The boot lights were on but very dim. 

Now here is the strange thing, as soon as i got into the car from the passenger door all 4 side lights came on and are still on despite plugging into my battery smart charger which i will leave on now until the battery is fully charged. By the way i had my battery checked 3 months ago out by the company that fitted it 4 yrs ago and it passed  their test.   

Any suggestions how to turn off the side lights would be much appreciated, Now that darkness is coming very nice people are now knocking on my house door to tell me iv'e left my lights on!

Thanks, Paul. 

[Big John]

Hi Paul

My guess is that the software on one, or more modules, has been corrupted by the low voltage. It happened to my XF during the Covid lockdown and stopped the rear doors locking / unlocking and the rear windows opening and closing. Sorted under warranty for me by dealer (non-jaguar). I think if the garage use the Autologic system they should be able to sort it for you. Apparently Jag dealers like to replace the module which costs rather a lot....

For the future I would recomend using a battery maintainer (I use Ctek) if you are not using the car for that long, and probably as a regular habit at least every couple of weeks.

As an aside I would replace the battery at least every 5 years as they are a consumable and do deteriorate with age/use and particualry if allowed to go flat...

Good luck

John

[Freebird Paul]

Hi BIG John,

Thankyou for your valuable thoughts, turned out i was lucky as after calling the AA all i had was a dead 5 year old battery which he replaced for me at just shy of £200. No corrupted software or any module issued were found after starting for the first time with the new battery. All i had to do was reset the park brake and windows and all was good to go.

Cheers and regards Paul.

[N6 JMX]

Hi Paul, good for you. The life span of a battery in a Modern XK is around 5 years with a good proactive maintenance call to change the battery when it gets to that 5 year mark. It's amazing just how many faults the Modern XK can throw up simply because the battery is on the wane.

In these cars, the ability to start the car is not a good indicator that the battery is fit for further service as the electronics that make this car work are simply very sensitive to low voltage.

The takeaway lesson should be to have the car on a Smart Charger - Ring Automotive or C-Tek - when leaving the car idle for longer periods. In my own case, if my car is going to be standing for more than a couple of days, I connect up my Ring Automotive RSC612 Smart Charger to the remote charging posts in the boot. The RSC612 will also work on vehicles with an AGM battery for Stop/Start technology.

Happy motoring.

N6 JMX