Anthony
Welcome to the wonderful and sometimes frustrating world of Jaguar ownership and maintenance. They are somewhat renowned for battery discharge. I personally (as many others on this forum have) invested in a CTEK MS 07 battery charger and restorer. I use it very regularly , at least once per month and always for at least 24 hours. It keeps the battery well maintained and greatly reduced the number of fault codes and starting/running problems that can arise from a lower charged battery.
Best Wishes and Regards, John