Dennis
Jaguar, in general can be a problem with battery discharge. Using a CTEK Re-conditioner/Charger regularly and for at least 24 hours can resolve/stop a lot of low battery potential problems.
"Other makes are available" ........... as the media would state. You will find a lot of people on this forum , including myself, use the CTEK product. I have a CTEK MS 7, which is also capable of starting flat batteries.
Best Wishes and Regards, John