As soon as the weather (in Montana) got really cold, my son's 2013 Ford Fusion Hybrid SE wouldn't start. He needs to get a boost anytime the car has been parked for more than about an hour. The battery has been tested (twice) and he's been told it "passed with flying colors". He has also been told it has a CCA rating of 390. I get the impression from reading these forums, and searching online, that the newer model of the battery (99RT4) has a higher rating (470?). Is this correct? Will getting a newer model battery (will have to be ordered--neither the Ford dealer nor local automotive retailers have it in stock) solve the cold weather starting problem?