On the various Hoth maps, if the player does not have the Jump PackStar Card equipped, the player's back will have a battery pack equipped instead. This closely resembles the battery packs attached to Snow Troopers, which heat their suit and helmet up to protect them from the cold environment. The reason these battery packs appear on Pauldron Stormtroopers and Snow Troopers is that without them, they would freeze to death quickly.
Strangely, the Scout Trooper, Shadow Trooper, and Shock Trooper do not come equipped with a battery pack on maps with a cold environment. Mentioned earlier, without a battery pack they would freeze to death in cold environments.