The first thing to know about heaters in EVs is that they differ from the ones found in gas-powered vehicles. Internal combustion engines produce a lot of heat, and some of that heat is directed into the cabin to warm your passengers on a cold winter’s morning. Electric cars, of course, don’t have engines. So how are their cabins heated?
EVs rely entirely on electricity to produce heat for their cabins, and early electric cars like the original Nissan Leaf and Mitsubishi i-MiEV used resistive heating for this process. (Some modern EVs like the Rivian R1T still do.) The process is fairly simple and works a lot like a space heater you might find in a home. Essentially, electricity is run through a conductor to produce heat. Air is then blown through the heating element and into the cabin and, just like that, an EV has heat. But resistive heating uses a lot of energy, and running the heater, in conjunction with colder exterior temperatures, drastically reduces an EV’s efficiency and lowers its estimated range.
Positive temperature coefficient heaters work in much the same way that resistive heaters do, but with one key difference. When current is first applied to the heating element, it gets hot quickly, but as the temperature rises, the current pull decreases and the electrical resistance increases to reduce the risk of overheating. Thanks to the reduced current requirement, PTC heaters are more efficient than their resistive heater counterparts.
But there’s another heating method that’s becoming more popular in modern electric cars: the heat pump. Heat pumps are nothing new — the Nissan Leaf, for instance, has used a heat pump since 2013 — but not every new EV uses one, and they are far more efficient than either resistive or PTC heaters. Heat pumps work a lot like your air conditioning does, only in reverse.
Air is drawn from the outside and run through a condenser that contains refrigerant. The refrigerant is compressed and that creates heat. The hot air is then pumped into the cabin to warm it up. The reason heat pumps are a favorable alternative to traditional resistive heating is twofold. The first is that heat pumps can also help cool down the car, serving as an air conditioner as well. Additionally, the process is more efficient than resistive heating and puts less strain on an EV’s battery and reduces the range penalty an EV takes when heating up.
Regardless of how efficient the heater is, using it will hurt your EV’s range simply because power is needed to operate it. However, because heaters are used when it’s cold, and cold weather by itself is enough to degrade range significantly, EV drivers need to deal with two factors negatively impacting range.