hello ,

Usually on my other cars , in order to keep the battery fully charged when car is left unused for a fews days/week , I use a small power supply connected to the cigar lighter ( when plugged before ignition ) or directly on the battery

This allow me to keep battery usually more than 10 years ( 15 on a Land Rover )

These power supply automicly stop feeding the battery when 13,8 V is reach

On such an "electronic " car than our X350 , I am afraid of putting my power supply on the car

Has someone use this solution with succes on his XJ ?

Thanks for all the help and info we find here

 

I used a Battery maintainer on my 04 all last winter with no problems. I connected it directly to the battery. If I remember correctly the cigar lighter is a switched circuit and will not work.