Electric vehicle fires are extremely dangerous and difficult to extinguish, but they actually occur a lot less frequently than gas car fires. That said, if your EV appears to start smoking while charging in cold temperatures, don’t call 911 just yet. It may just be steam from the heat pump, which is necessary to get the battery up to the ideal temperature to maximize charge speeds. All new Tesla models and many other new EVs have heat pumps, and can warm up or precondition the battery to the optimal temperature for DC fast-charging, which is around 122-degrees Fahrenheit. In some climates, the warm heat pump can emit some steam, but it’s totally normal and nothing to worry about.
Cold weather poses unique challenges to electric vehicles. EVs use massive lithium-ion batteries to store electricity, but the chemistry inside the batteries slows down in cold temperatures. You can’t plug into a DC fast charger like a Tesla Supercharger with a cold battery and expect it to charge at its maximum rate; in fact, it can put excess stress on the battery to do so. Fast charging a battery when its internal temperature is colder than 32 degrees Fahrenheit can cause a phenomenon called lithium plating.
So when should you worry when you see steam or smoke coming from your EV’s battery? Tesla says that its thermal system may produce steam under certain conditions for vehicles with heat pumps, and that odorless steam can come from the front of the vehicle while charging at a Supercharger in cold temperatures. Popping or hissing sounds are early signs of thermal runaway that causes EV fires, and it’s said that a cherry bubblegum scent can be present. Dark vapor or smoke coming from the battery or the rear of the vehicle is also cause for concern. If you notice any of these issues, stay away from the vehicle and call emergency services. If there’s just odorless white steam coming from the front of the vehicle where the heat pump is, then it’s likely just from the heat pump.
