I have used my battery booster dozens of times to start small and large vehicles but I also carry jumper cables as a backup.

It has been nice to have the booster pack when my car has sat at a trailhead in -30C for a week and there are no other vehicles around to hook cables up to.

The battery pack is also easier to hook up than cables as you do not need to maneuver vehicles into position which can be difficult in deep snow.

When traveling in really cold weather I also pack a battery charger and a long extension cord.