After 3 weeks of sitting in the garage under car the cover, my '04 XF turned over slowly but still started! I guess the cold weather may cause the battery to drain more than in summer. After researching several trickle charge brands, went with NoCo (NOCO - Genius) and it was on sale. Purchased the quick release accessory too - making it easy to connect. Top quality and easy installation. If your XF sits undriven like mine, under $50 to keep your battery healthy & always charged. Hope you find this useful,


Either available on amazon or the manufacturer

Easy installation

 

I always keep a trickle charger on mine while sitting. It really extends the battery life and the car electronics.

 

Think I have six of the Genius 1s now. Has got AGM and a "force" mode for a really ded battery. Also have larger smart chargers when need a fast charge and a 225 amp roll around (not sure why, mustabin cheap).
The Genius 1 was often on sale for $19.95 on Amazon.