As winter weather arrives, electric car owners are worrying about what the cold will do to the range of their vehicles. Message threads with titles like “Winter driving warning” and “Another way to stay toasty on long trips without running heat” are showing up on online customer forums run by Tesla Motors, which sells many of its cars in particularly cold places such as Norway.

Cold weather presents two main challenges for electric vehicles: cold air limits battery performance, and running the heater drains the battery. As temperatures go below freezing, some drivers accustomed to traveling 250 miles on a single charge have seen their car’s range drop to 180 miles.