EV A/C power draw explained: summer range loss and heat pump vs PTC

Bottom line: running the A/C in an EV does cost range, but how much depends on the vehicle, the speed and the settings. Public tests mostly land around a roughly 10% loss in hot weather, while lab models show 30%+ in worst cases. Heat pump vs PTC matters far more for winter heating than for summer cooling.

Video thumbnail: The Engineering Core

What happened: a new video on EV climate control

The latest video on the The Engineering Core YouTube channel asks whether A/C really is what drains an EV in summer. Going by its title and description, it covers:

• How an EV air-conditioning system uses energy: the electric compressor, blower motor and electronic controls.
• Why an EV keeps losing charge in traffic or when parked with the A/C running.
• Heat pump vs PTC heater, and why different EVs can show very different climate-control energy use.
• Windows down vs A/C at low and highway speeds, plus practical savers: pre-cooling while plugged in, a reasonable temperature setting, ventilated seats and reducing heat buildup in the sun.

Public data first: In AAA's 2026 chassis-dynamometer tests (cabin set to 72°F), EVs at 95°F (35°C) showed about 8.5% less range and 10.4% lower efficiency than at 75°F (AAA). Argonne National Laboratory, under similar conditions, found range about 14% lower on average (Argonne). Vehicles and methods differ, so the two numbers are not interchangeable.

Engineering point 1: how much power does the A/C draw?

The compressor moves heat from the cabin to the outside, so demand tracks sun load, starting cabin temperature and speed. An older NREL/SAE model assumed a 7 kW peak thermal load at a net COP of 2.33, which is about 3 kW of electrical draw at peak and about 1 kW for steady-state in a small sedan. On the SC03 cycle that cut simulated range by about 36% and 16% respectively (OSTI). That is an old-model simulation, so treat the kW values as to be verified for current vehicles.

Lab tests in Europe add context: over WLTC at 35°C, the JRC found mobile A/C energy equal to roughly 15%–18% of the energy needed at the wheels, versus 35%–45% at −7°C. Heating energy in the cold could be 4 to 10 times the cooling energy in the heat (JRC).

Engineering point 2: why city driving and parking hurt more

A/C is a cost per hour, not per kilometre. One study at 35°C reported energy use up about 24% in city driving and 12% on the highway (IJAT 2024). On the highway, traction power is large, so the A/C share is diluted; in slow traffic the same trip takes longer and the A/C share grows. Parked, there are no kilometres to spread the load over, and the first cool-down after heat soak is the most expensive. NREL measured up to 0.92 kWh (66.5%) saved on a 20-minute cool-down with solar-load reduction plus zonal cooling (NREL).

Engineering point 3: heat pump vs PTC

A PTC heater converts electricity to heat at about 1:1 (COP≈1). A heat pump moves heat from outside into the cabin, so COP can exceed 1. In a same-model dynamometer comparison, the estimated heat-pump COP was 1.53–3.33 at 0°C and 0.80–1.93 at −10°C, and retained range was 1%–15% better than the PTC car (average 4%–7%) (MDPI WEVJ). The advantage shrinks as it gets colder, and resistive backup is still needed in extreme cold.

In summer, both architectures cool with a refrigerant compressor. A Politecnico di Torino simulation at 42°C found similar performance, with only a slight heat-pump advantage (Politecnico di Torino). So the big heat pump vs PTC gap is mostly a winter story; summer differences between EVs come more from the vehicle, insulation and control strategy.

Engineering point 4: windows down or A/C, and what actually helps

The evidence I found on windows vs A/C comes from combustion cars, not EVs: a Corolla and an Explorer at steady 64–113 km/h burned more fuel with maximum A/C than with windows down, and the Corolla only matched A/C at about 121 km/h (Huff et al.). Whether this carries over to EVs is to be verified, though the physics (more drag at speed) points the same way.

On savings, NREL notes that pre-conditioning on grid power takes the initial load off the battery (NREL), and zonal airflow cut climate-control energy by up to 16.7% at the same airflow (NREL). Both match the video's pre-cooling and ventilated-seat tips.

Open questions / to be verified

• Current-vehicle A/C power in kW: to be verified (the 1 kW / 3 kW figures are old-model assumptions).
• Test conditions differ (AAA and Argonne are US dynamometer tests, JRC is EU WLTC, others are simulations), so percentages should not be mixed across studies.
• Windows-down vs A/C for EVs: to be verified (the tests cited are on combustion cars).
• Real-world results will vary with humidity, sun load, tires, speed and each vehicle's control strategy.

Watch the video

• Does EV Air Conditioning Kill Your Range? How Much Range Do You Really Lose? (The Engineering Core YouTube channel)

Your turn: Do you pre-cool, open the windows, or just run the A/C hard? How much range do you see lost in summer?

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Sources: AAA (2026), Argonne, NREL/OSTI, EU JRC, Springer IJAT, MDPI WEVJ, Politecnico di Torino, Huff et al. on A/C fuel use. Figures are for reference only.
Published on The Automation Core (https://theautomationcore.blogspot.com). Video: The Engineering Core YouTube channel.