How Much Does Air Conditioning Reduce EV Range?


Photo Courtesy of Rivian

Climate control is the system used to keep the interior of the vehicle comfortable for the driver and passengers. Heating when it is cold out and cooling things down when it gets hot makes driving much more bearable. Having a working climate control system also makes it safer to drive as the interior of the vehicle can rise to dangerous levels in the summer.

How much does air conditioning reduce EV range? Using an air conditioner while driving in 95 degree Fahrenheit weather will reduce battery range by 17%. For the majority of EV’s that translates to around 30 miles of range. Using the heater reduces EV range by double the amount the AC does. Expect to lose 60 miles of range in extreme cold temperatures.

But to use such conveniences requires some energy and unfortunately it is the range that suffers. In other words, you will not be able to drive as far if you are using the air conditioning or heater. This article will dig into how much the AC affects the range, how the HVAC system works, and ways to maintain range and stay comfortable.

How Much Does AC Affect Range

To understand why the climate control system affects the range, we need to look at how it works in electric vehicles. The basis for any system in an electric vehicle is of course the battery. Every single component uses energy from the battery in some way. Since the battery is designed to power the drive motor, every other system steals from that intended power. Any extra draw from the battery shortens range.

In addition to various accessories drawing power, range can also be shortened by outside forces. For example, batteries are adversely affected by higher temperatures. Coincidentally, this will also be when the AC is being used, which is a double whammy to the battery. Likewise, extreme cold temperatures can do a number on battery range while the heater will also be running. Both hot and cold require a lot from the battery and unfortunately range will always suffer.

So, how much will the climate control system affect range? Most of the time, it is going to depend on individual driving habits and conditions. However, a study done by Car and Driver magazine put a Tesla model 3 to the test, specifically in cold weather with the heater on. According to the article, using the seat warmers and heater on full blast dropped the range over 60 miles compared to the same distance with no HVAC running. This works out to using 35% more energy and significantly drops the range. 

In warmer weather, there still is a cost to keeping the cabin comfortable. A study done by AAA found that on average, across a few different makes/models, the range fell by 17% when driven in 95 degree conditions using the AC. Apparently, Tesla disputed this claim, stating that Teslas drop only about 1% in 95 degree conditions. 

Range When Using The AC vs Using The Heater

Let’s look at how these systems work a little deeper to understand why there is such a cost for using them. Traditionally, the engine was responsible for powering the heating and cooling. Excess heat from the engine would be captured in the coolant system and plumbed into the HVAC system in order to warm up the interior. Similarly, the engine powers the AC compressor which circulates refrigerant that is plumbed through the HVAC system to be able to cool the interior. However, without an engine, the way that this is done in an electric vehicle is different.

First, we will think about the AC compressor. Generally speaking, a compressor is spun to compress and pump refrigerant through the air conditioner system. On a normal vehicle, the compressor is driven by a belt and is turned on and off using an electric clutch. On an electric vehicle, the compressor still spins, but it is electrically driven off the high-voltage (HV) batteries.

The refrigerant evaporates in the HVAC unit which cools down the air. It is the same effect of spraying a water sprayer, only in a contained unit. The evaporated gas gets carried to the condenser, where it warms up a bit and turns back into a liquid. Minus a few switches and controls, that is the basics of an air conditioner system.

The heater, on the other hand, is a different story. As mentioned above, the traditional heater harnessed some extra heat from the engine and plumbed it so we could warm our shoes and defrost the windshield. However, without engine coolant, this process does not work in an electric vehicle. Instead, there is essentially a space heater built into the HVAC system. As air is blown by the heater, the air warms up and carries that heat around. While this does work well to create heat, it is incredibly energy inefficient. If you have ever run a space heater in your home, you know how much electricity it uses. 

So, now that we have a decent handle on these systems, it is fairly easy to see how the range is affected. There are a lot of moving parts that require extra energy to function properly. In order to combat this, many automakers are engineering heat pump systems in electric vehicles. A heat pump is essentially a combination of an air conditioner system and heater system.

The pump is able to be reversed and instead of radiating heat outside, it can gather ambient heat and bring it inside, and vice versa. Overall, this system works really well except in extreme temperatures. When cooling, if the heat can not be radiated, the air will not cool down much. Likewise, if the heat pump can not scavenge enough ambient heat, there is not much it can do. In spite of these drawbacks, it is much less taxing on the vehicle range.

How To Optimize Driving While Using AC

Here are a few things to do to help maximize battery power in hot or cold conditions:

  1. Warm up or cool down vehicle while charging
  2. Park vehicle in shade or garage
  3. Dress for the weather 

Since heating or cooling are so taxing on the battery, consider warming or cooling your car while it is still plugged in. That way, some of the energy cost is made up during charging. For example, if your car is in the driveway charging overnight, go out and turn on climate control prior to the morning commute and before disconnecting the charger. This can also work when charging at a super charging station. Just turn on the climate control while charging to maintain cabin comfort while you wait.

Whenever possible, park the vehicle indoors or under some shade. Parking in the garage is ideal because the vehicle will be insulated against the weather and the charger is close at hand. This will keep it cooler during the summer months and will help warm up during winter. Vehicles in general aren’t insulated well, so parking anywhere that can help with the temperature will help.

While there is not much more we can do about vehicle insulation, we can insulate ourselves. During colder weather, it is wise to dress with extra layers. This will keep body heat trapped and will lessen the need for the car heater. Similarly, when it is hot outside, dress in breathable clothing so that your body can cool itself. 

Lastly, driving habits affect range as much as anything. Aggressive acceleration and driving and higher speeds consumes more energy. So in order to preserve range while using the heater or air conditioner, make sure to ease on the throttle and slow down a bit. 

Tips To Reduce Use Of AC

Here are a few tips on lowering the use of the air conditioner. First, drive with the windows down when possible. This does not always cool things down, for example on an extremely hot and muggy day in slow traffic, but generally speaking the flow of air will keep the cabin temperate. Just lower the windows a bit all the way around and adjust as needed. Of course, nothing beats cruising with the window down on a nice summer day. 

Also, whenever possible, you can time your drive with the rise and fall of the temperature throughout the day. it is likely going to be warmer during the middle to afternoon hours and the coolest temperature during dawn or dusk. 

Another option is getting the window tinted. Before we get too into it, realize that window tint laws are regulated state to state, so be sure to check before getting any work done. Tinting windows can block nearly 99% of Ultra Violet rays and can block almost half of the heat from the sun. This can make a huge difference in lowering the cabin temperature. There are many do-it-yourself kits for tinting all windows, but having a body shop perform the work is a good way to have it done right.

Conclusion

Hot and cold temperatures can inherently lower the range of an electric vehicle. That range is further threatened when using the climate control system to cool down or warm up the cabin. In some cases, these systems can drastically use up range and raise the possibility of running out of charge prematurely. There are ways to get around constantly using the AC or heater and doing so helps maintain vehicle range.

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