2007 XJ8 VDP- Purchased this car in Sept, 2012. 25,000 miles. It is a second car used only on weekends. Had it home three days and battery seemed to be dead. Dealer replaced battery. Drove 3 times over the next 8 days then let it sit for two weeks. Battery drained again. Seems that something is continuing to draw current from the battery when car has not been used for 10-14 days. Dealer can't find anything wrong. Help???

Submitted by stevejag@sbcgl… on Tue, 07/30/2013 - 15:34

Tom, bear in mind that with these newer cars have normal parasitic draws that can drain a battery low enough to be unable to start the car in about 21 days. I know some will say their car will go longer and still be able to start, but the reality is, three weeks is about the max you can expect reliably. If you make it longer, that's just a bonus; and condition of the battery plays a big roll.

I know your dealer will probably roll their eyes at you, but ask them if they made sure the 'Switched System' relays are reliably shutting down properly. Testing that system thoroughly will take the better part of a day because of the wait time for shutdown. By that I mean some things remain powered for up to 40 minutes after you remove the key. They need to be sure that goes to sleep properly EVERY TIME the car is shutdown, and then be sure it stays that way, and doesn't wake back up.

Good luck!