There are many factors that affect electric vehicle range. Just like with ICE (Internal Combustion Engine or “gas”) vehicles, electric vehicles (EVs) experience reduced efficiency during certain conditions. While some of these factors can be mitigated through driving behavior, most are just the realities of real-world driving.
The EPA may rate a vehicle for a certain efficiency, say 141 MPGe (Miles per Gallon Equivalent) for the Tesla Model 3 Standard Range Plus, but in reality, the range may be lower due to these particular factors.
Factors That Affect Electric Vehicle Range:
Speed kills. Tongue-in-cheek joke aside, driving at high speeds (65+ MPH) reduces the electric car’s efficiency. The reason for this is the faster you drive, the more work the electric motor has to do. Anecdotal data from Teslike shows the impact on range from increasing speeds as shown in the below image.
As you can see, the Model 3 Standard Range Plus with the aero wheels has an EPA rating of 240 miles–though currently it is now rated at 250 miles. At 65 MPH the range is right at the current EPA rating. However, at 70 and 75 MPH the range decreases to 232 and 213 miles, respectively.
In essence, expect about 15% loss of range when driving at 75 MPH. This is consistent with my 2017 Chevy Volt. The Volt is rated at 53 miles per charge (it’s a plug-in hybrid so there is another 350+ miles of gas range after the battery is depleted). At speeds of 75 MPH I routinely see only 44 miles or so.
Another factor that affects electric vehicle range is wind–headwind that is. This one is fairly straightforward. The higher the headwinds, the more resistance the vehicle experiences, therefore, the motor has to work harder to combat the negative effect. Unfortunately, there is not much data behind this yet to put a quantitative percent decrease per wind MPH.
Like wind, the more payload the more the motor has to work to offset the weight. There is minimal data to, again, quantify this as a percent decrease per payload weight. However, it is safe to say the more passengers and cargo you load into the vehicle, the less efficient the EV will be.
4. Tire Traction
Poor tire traction results in less efficiency. The three factors that contribute to tire traction are tire quality, tire inflation, and road conditions. If you are driving an EV with tires that are at the end of their life and the roads are wet from rain, then you can expect the range to slightly decrease.
Additionally, under-inflated tires will not only not perform as well, but will also not be as efficient. Poor tire traction will not impact range as much as speed, however, it still plays a part in range loss.
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5. Cold Weather
The cold ambient weather is unfriendly to electric cars. Specifically, EV batteries are not fond of cold weather. This is because they need to operate at a neutral temperature. Excessive cold, or excessive heat, will result in loss of range.
During cold ambient temperatures, the battery will need to use energy to heat itself up. With an ICE vehicle, the engine block creates a vast amount of heat (that is wasted to the environment), which can heat up the cabin, fuel, or other vehicle parts and functions. Naturally, the ICE vehicle warms itself up for optimal operation. With an EV, that heat needed to warm essential parts and functions must be created using energy from the battery.
During cold weather (below 50 degrees Fahrenheit), you will start to find a slight drop in range due to the battery needing to warm up. Below 30 degrees, the range loss becomes more apparent. In a study by AAA, electric cars experience a range loss of 12% in 20 degree F temperatures. And that is with the HVAC (Heating Ventilation Air Conditioning) off.
This leads to the next factor that affect electric vehicle range–HVAC.
Utilizing the HVAC, or heating in this case, during cold ambient temperatures will result in range loss. Simply put, using the heating system uses energy, therefore, range is lost from the battery using energy to heat the car rather than to move the wheels.
A typical car heating system consists of a radiator, water pump, thermostat, blower motor, and coolant. With an ICE vehicle, the natural heat byproduct from the engine is used to heat the cabin. With an EV, that heat must be created (so to speak). Energy from the battery, just like when the weather is cold, must be used, but in this case, to warm the cabin.
Per the aforementioned AAA study, EVs can experience as much as a 41% loss of range when using heating when ambient temperatures are 20 degrees. It is important to note that that decrease in range is coupled with HVAC use and ambient temperature rather than a multiplier to the previous cold weather section. Regardless, it still can be eye opening. ICE vehicles, too, experience similar, but not as drastic, loss of efficiency with both cold weather and HVAC use.
Lately, electric cars are outfitted with heat pumps rather than the electric resistance heater to combat this loss of range during heating use. Essentially, a heat pump is like a refrigerator, but in reverse when heating (see above image).
Vehicles like the Kia Niro and Tesla Model Y have a heat pump, which can be as much as 350% more efficient than electric resistance heaters. This significant increase in the efficiency of the heating system will result in much less loss of range during cold weather HVAC use.
7. Battery Degradation
Lastly, battery degradation is a major factor that affects electric vehicle range. A brand new electric car will have a State of Health (SOH), which is the amount of battery energy available compared to when new, of 100%. Therefore, battery degradation, obviously, will not have any impact on the range since there is none at this point.
However, over time the battery slowly loses capacity. Unlike cell phone or laptop batteries, electric car batteries include a Thermal Management System (TMS). This ensures the battery to last as long as possible.
The subject of battery degradation can be quite extensive. Check out an article dedicated to just this topic here: Electric Car Battery Degradation.
Back to the subject of factors that affect electric vehicle range, EVs experience around 2% of battery capacity loss per year. There are many factors that increase or decrease this statistic so it is important to read the battery degradation article to learn the specifics.
While this list may seem long to some, there are several things drivers can do to reduce the loss of range such:
- Wear a jacket instead of using the car heater
- Drive under 70 MPH on the freeway/highway
- Accelerate slowly
- Pre-heat the cabin while still plugged in to reserve the battery for the trip
- DC Fast Charge only when you need to
- Upgrade to the heat pump trim if available (e.g. Kia Niro EV)
- Replace weathered tires with new
- Properly inflate tires
With this information, EV drivers should be better prepared to hit the roads without unexpected loss of range. Typically, I use a 25% range loss during a winter season long trip. This rule of thumb is subject to change as previously mentioned, however, it gives me a good starting place of how much range I’ll have given the applicable factors (e.g. cold weather, heater use, highway speeds, etc.). Your specific results may vary.
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