Anyone ever experience this problem with dc 40 collar

[Tusk Hog]

   I keep my collars and chargers in my shop. Yesterday it was cold, even in the shop with doors closed and a warm fire burning in the stove. The collars wouldn't charge. Today it only reached 37 degrees but the collars charged. Anyone else ever experience this? Guess I will start charging them in the house. Wife frowns alittle, they occasionally smell, little skunky.