I have a 2016, XJL, 3.0 L supercharged.
I have discussed this issue earlier also regarding the message “low battery start engine soon”. This is happening for last 4-5 weeks while I do not have any problem to start the Engine even at low temperatures in morning hours: please guide me:
1) should I replace the battery ( it is I guess the original VARTA battery ) and if I do ,
a) should I get it done at the dealership, which is very costly.
b) get it fixed at a genuine interstate battery dealer or
c) do it myself. I find very simple to do it.

for item a) above, the dealer as usual has scared the hell out of me by informing me that there are many electronics/ software related steps which ONLY a dealer can do it.

for item b) above the battery suppliers supplying the same battery advised me ignore them as the system will automatically readjust all electronic and SW related issues.

Any advise/ feedback or suggestions?? Someone also tested the battery and according to him there is no issue with the battery.

PS: I do not drive the car more than 35-40 miles per day and mostly within 20 miles radius. I did drive to the airport last week ( 75 miles total ) and the sign was gone for couple of days.

 

I got the battery changed from interstate battery supplier. However, the “low battery, start the engine “ is still there?? What did I do wrong??

 

I think you're in the wrong forum, this one is for XJ6/XJ12 up to Series 3 in 1992. Your car is way beyond that, but I don't know what series that maybe to direct you. Usually one of the moderators re-posts incorrect models into the correct one.