Chrysler has used the ThermoGuard battery shield since the 1970s.It was designed to insulate the heat of those big 400/440 engines.Today you see a flimsy wrap around the battery of Chryslers/GMs.To be any effective against the cold,it would need to insulate the bottom and top too.They have battery heat plates and blankets,but no top heater (probably due to heating battery fumes).