Batteries are somthing of a wild card for me.
I have a 06 Chev and yesterday at 42 below I hit the auto start, I watched and listened from inside the house, it turned over slowly and just started, I began thinking about getting a new battery. When I went outside I realized that I forgot to plug the truck in, damm good battery from 06. At work I plugged it in for the ten hour shift, so the battery blanket could warm the battery and I drove home the long way to give it a good 30 minute charge.
Other batteries removed from equipment kept "warm" all winter can go bad in three years.
For years now I have always used the ten amp chargers, they are great, and will start a dead car in about ten minutes, if the battery is good.
We have an asphalt trailer at work, trickle charger all winter, new battery somtime every summer.