Recent reports described people stranded for up to 19 hours on a Virginia highway in freezing weather during a winter storm. To stay warm, people ran their cars&#; engines, heating their cabin and protecting against hypothermia. The fuel gauge moves ever so slowly toward &#;empty,&#; with occupants assured of a reasonable number of hours of comfort before the situation becomes unsafe. And, while it&#;s possible to run out of fuel in a situation like this, it&#;s rare that traffic jams last long enough for fuel endurance to be of grave concern.
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As the adoption of electric vehicles expands, the variety of climates and geographies where they are driven increases accordingly. Gone are the days of EVs being exclusive to sunny California! Many are aware of the quantifiable limitations of an EV&#;s range in cold weather (if not, check out our report on the truth about winter EV range loss). But what about the safety and endurance of an EV in hazardous conditions like a white-out? What exactly happens when an EV gets stuck in a winter storm &#; and can it keep its occupants safely warm for as long as an internal combustion engine vehicle?
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There are numerous misconceptions abound about how long you can &#;survive&#; a winter storm in a stranded EV, with most time estimates being drastically underestimated. But not to worry, we have battery science on our side!
First, here are a few points of reference about gasoline cars as they idle in cold weather:
The first concern about idling in cold weather is moot in an EV. There are no tailpipe emissions to worry about; an electric car&#;s heater can be safely run regardless of fresh air ventilation.
The second point is largely a commonality between gas and electric cars. The amount of time you can sit in a car with the heat on is determined by how much fuel is in your tank or by the battery&#;s state of charge. However, unlike in the gas car, it is not common or practical to recharge an EV while stranded. However, mobile chargers and emergency batteries will grow in popularity as EVs become more common.
For the third point, given the enormous range of fuel efficiency and tank sizes on gas cars, it&#;s hard to nail down an exact figure for how long one can idle in cold weather. We&#;re using 30 hours as a baseline, assuming a full tank of gas in an average ICE vehicle.
Lastly, while a gas vehicle does generate its cabin heat through a very inefficient process, the same is true for most electric vehicles. In a stationary EV, there is little waste heat, so cabin heat is generated by heating up resistive elements, drive stators, or through heated seats or steering wheels. This heat also costs energy, and figuring out exactly how much it uses determines how long an EV can keep occupants warm.
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Let&#;s assume we have an average EV as per stats: around 250 miles of range powered by a battery with around 70 kilowatt-hours of capacity. There are five variables that affect how long you can heat an EV while sitting, in rough order from most important to least important:
How does this all play out practically? Let&#;s take for example an EV with a resistive heater, like the Volkswagen e-Golf. It is a small car with a small battery, and a small cabin to heat. Because of its resistive heating elements, all heat generated for the cabin costs the same regardless of whether or not the vehicle is moving. Drivers report approximately 1.5-2.5 kW of heater draw in outside temperatures from 35 to 15 degrees Fahrenheit. With 50% charge on a 32kWh battery, that translates to between 6.5-10.5 hours of heat on a 15-35 degree day; double that on a full charge.
For more information, please visit How Does Electric Cars Heating Work.
But what about a modern EV with a bigger battery and better heating options, such as heated seats?
Enter the Tesla Model 3. For , Tesla switched from resistive heating to a heat pump. Drivers report greatly improved efficiency when it comes to heating their cars. One user slept in his Model 3 and ran metrics on it overnight in sub-freezing weather, finding the battery consumed 1.36kW per hour, on average. For a Tesla with a 80kWh battery, this means you could sit in your Tesla nice and toasty for almost 59 hours on a full charge, or about 29 hours on a half charge.
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In fact, while writing this post, I decided to run a quick test on my own Model 3. Although I am in California where the temperatures aren't as cold as the Northeast, I blasted the heat in my parked car for 30 minutes. I set the temperature to "hi," which is the only temperature setting above 81 degrees, and boy - was it warm in there! After running for half an hour, my battery percentage declined from 88% to 85%, indicating that I used 3% charge over 30 minutes to make my car uncomfortably warm. At this rate, 6% an hour, I would still get at least 12 hours of heat, and honestly, no one would want it to be that warm for that long!
Starting the experiment at 88% battery capacityTo conclude, modern EVs with average battery packs offer cold weather heating endurance equaling or exceeding that of average gasoline cars, with the added benefit of not needing to worry about carbon monoxide poisoning. For some, this ability may come as an added luxury. For example, drivers report using their EVs for camping, readily using the heat all night without compromising too much range for the next leg of their trip.
Do you have a story to tell about using your EV in cold weather situations? We&#;d love to hear! Get in contact with us.
If you&#;re thinking about buying an electric vehicle (EV), you might be wondering how the cabin heating works in it. EVs have climate-control systems. They can blast cool air into the cabin during the summer, and they can blast warm air into the cabin during the winter. With an electric engine, though, EVs leverage a different technology for cabin heating than traditional vehicles.
Vehicles with a traditional internal combustion engine (ICE) use coolant to warm the cabin. The primary purpose of coolant is to remove heat from combustion engines. As they ignite air and gas, combustion engines will heat up. Some of them can reach temperatures of up to 2, degrees Fahrenheit. If left unchecked, the heat will continue to increase while potentially causing catastrophic damage to the combustion engine.
Coolant will remove heat from the combustion engine so that it&#;s protected from damage. Coolant will flow through the engine where it absorbs heat. It will then travel to the radiator where a fan releases the heat into the surrounding environment.
If the driver has the heater turned on inside of the cabin, coolant will also travel to a miniature heat pump known as a heater core. The hot coolant will be redirected to the heater core after leaving the combustion engine. While at the heater core, a separate fan will blow over the heater core. This will create hot air that enters the cabin to warm it.
There are different types of climate-control systems for EVs. Some EVs use an electric coil to warm their cabin. They work like space heaters. When you turn on the heater inside of the cabin, electricity will flow through a metal coil. The metal coil will then heat up, and with the help of a fan, it will produce hot air for the EV&#;s cabin.
Other EVs use a heat pump. Heat pumps are climate-control systems that are commonly used in homes and commercial buildings. To cool a home or building, they will transfer heat out of the indoor space using equipment similar to that of an air conditioning system. To warm a home or building, they will transfer heat from an outdoor space into the home or building.
In the past, most EVs used an electrical coil for cabin heating. While electrical coils aren&#;t obsolete, they are gradually being phased out in favor of heat pumps. Heat pumps are more efficient. And with their high efficiency, heat pumps can extend the driving range of EVs.
If you want to learn more, please visit our website How Does a Heater Work in an Electric Car.