Hot weather significantly affects the range, efficiency, and performance of electric vehicles (EVs). This article discusses how high temperatures impact batteries, tires, and cooling systems. It also compares the performance of popular EV models in hot climates, highlighting key steps drivers can take to protect their vehicles from excessive heat.
The impact of hot temperatures on EV batteries
EVs rely on lithium-ion (Li-ion) battery traction packs to power their drivetrains. These batteries operate most efficiently within a 60° to 95° F (15° to 35° C) temperature range.
Above 95° F (35° C), EV Li-ion batteries typically begin to overheat, leading to faster discharge rates, reduced energy storage capacity, and inefficient power delivery over time.
Figure 1. An EV driving on a hot California desert road. (Image: EVEngineering)
At high temperatures, the movement of ions within batteries increases rapidly, preventing effective binding to anodes and cathodes. Temperatures exceeding 104° F (40° C) threaten the integrity of the anode’s passive emission layer and accelerate liquid electrolyte depletion. Extreme heat causes microcracks, slows crucial chemical reactions, and shortens battery life.
Hot climates (Figure 1) also increase internal battery resistance, extending charge times and reducing EV range. According to a recent Recur study, average range loss at 80°F (26.7° C) totals 2.8%, rising to 5% at 90° F (32.2° C) and 31% at 100° F (37.8° C).
High temperatures can also reduce regenerative braking efficiency, as the battery’s charge acceptance may lower to avoid overheating.
Although some EVs with advanced thermal-management systems mitigate this effect, adjusting regenerative braking settings, as the manufacturer recommends, generally helps ensure performance and battery integrity in hot climates.
Dissipating heat with thermal-management systems
EVs rely on advanced thermal-management systems (TMS) to maintain optimal operating temperatures and prevent overheating. These systems include cooling loops that use electric pumps to circulate coolant fluid around key components such as Li-ion battery packs, electric motors, power electronics, and drivetrain.
Notably, the TMS and battery-management system (BMS) work in tandem to monitor and regulate battery temperatures.
Radiators within TMS cooling loops play a crucial role in dissipating heat into the ambient air — as air-conditioning (AC) systems with integrated evaporators further cool vehicle components and the cabin. Some advanced EV designs integrate these systems to bolster overall efficiency and cooling effectiveness.
Indeed, EV in-cabin AC only minimally impacts range, especially compared to the high-energy demands of winter heating. This is due to the lower temperature gradient required in summer, generally around 20 to 25 degrees, as opposed to over 50 degrees in winter. The impact on range becomes noticeable only when temperatures exceed 85° F (29.4°C). Because EV AC systems operate independently of the drivetrain, they deliver immediate cold air irrespective of motor temperature.
How temperatures affect EV tires and regenerative braking
Summertime heat significantly impacts EV safety and performance by causing the air inside tires to expand. For example, a 30-degree increase in temperature from 75° F (23.9° C) to 105° F (40.6° C), can lead to a three-pound per square inch (PSI) jump in tire pressure. Tire overinflation compromises handling and braking performance, significantly increasing the risk of blowouts.
Hot weather accelerates EV tire wear, especially in dusty and sandy environments. This reduces tread depth, decreases traction, and increases hydroplaning risks. Additionally, high temperatures and UV radiation speed tire aging and cracking, while continuous exposure to high humidity causes rubber tire components to degrade rapidly.
Navigating summertime performance
The impact of extreme heat on range differs from vehicle to vehicle. The Chevrolet Bolt, for instance, retains 100% of its EPA range in temperatures averaging 70° F (21.1° C) to 75° F (23.9° C), with a gradual decline observed above 80° F (26.7° C), totaling 9% at 90°F (32.2° C). The Bolt’s AC system, consuming about 1kW for cooling, slightly increases energy usage by 2% to 4% for external temperatures around 75° F (23.9° C) — jumping to 11% for cooler cabin settings. At 100° F (37.8° C), energy use for climate control can surge up to 20%.
By offering various pre-cooling options, the Hyundai Kona EV frequently exceeds its EPA estimated range in temperate or warm weather, experiencing a 5% range reduction at 90° F (32.2° C). Similarly, the Mustang Mach-E, featuring auto cool settings for cabin temperature control, maintains robust performance above 85° F (29.4° C), with only a 1% range loss at 90° F (32.2° C). However, its range loss accelerates at around 93° F (33.9° C) to 95°F (35° C), with a 16% loss expected at temperatures of 100° F (37.8° C) and beyond.
The Ford F-150 Lightning, which offers two preconditioning options for cabin cooling, shows a 1% range loss at 90° F (32.2° C). The Nissan LEAF, also supporting pre-cooling, experiences range reduction at comparatively cooler temperatures, around 75° F (23.9° C), with a 22% range loss at 90° F (32.2° C). Its AC system draws up to 3.5 kW of energy for initial cooling, decreasing to 1kW to 1.5kW for cooler cabins.
Featuring heat pumps, cabin overheat protection, and “dog mode” — a function that safeguards interior temperature for pets when owners are away — Tesla’s maintain cool cabin interiors with minimal impact on battery range.
Figure 2. A graph illustrating the Tesla Model Y’s average range across different daytime temperatures. (Image: Recurrent)
Specifically, Tesla’s variable speed air conditioner consumes approximately 1 to 3kW under typical conditions, increasing to 6kW depending on internal and external temperature. Even in 90° F (32.2° C) weather, using Tesla’s AC system efficiently ensures minimal range loss (Figure 2).
Like all Li-ion-powered EVs, however, Tesla’s real-world range varies with temperature.
Mitigating the effects of hot weather
Managing EV battery temperature and limiting energy consumption can help mitigate the effects of hot weather. For example, pre-cooling the cabin when connected to the grid conserves battery life, while avoiding rapid, outdoor dc daytime charging prevents thermal runaway.
Moderating acceleration and speed, especially uphill, curtails power consumption. Keeping the battery state of charge (SoC) under 80% further minimizes voltage-related stress. Lastly, parking in garages or shaded areas reduces sun exposure and lowers vehicle temperatures.
Summary
Temperatures above 86° F (30° C) affect EV batteries, tires, and cooling systems. Although the impact of summer weather on range, efficiency, and performance differs from vehicle to vehicle, all EV drivers can take similar steps to mitigate the effects of extreme heat.
References
- Study: Summer & Hot Weather on Electric Car Range, Recurrent
- Deep Dive: Lithium-Ion Batteries and Heat, Recurrent
- How Hot Weather Affects your Electric Vehicle, EVision
- Electric Cars in Hot Weather – What You Need to Know, EV-Lectron
- 9 Tips for Driving and Charging an EV in Hot Weather, Kelley Blue Book
- Drivers In The Southwest Are Learning Electric Cars Don’t Like It Hot, Forbes
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