The use of HVAC systems in electric vehicles (EVs) has a significant impact on their driving range, especially depending on the outside temperature and the type of heating or cooling technology used.
Impact of Cooling (Air Conditioning)
- Running the AC in moderate temperatures (below about 85-90°F or 29-32°C) leads to relatively minor range reductions. For example, at 80°F, the range loss is about 2.8%, and at 90°F, it increases to around 5% across multiple EV models.
- However, in very high ambient temperatures (around 40°C/104°F), cooling the cabin along with key EV components can demand 5-6 kW of power, which could reduce the EV’s range by approximately 26-30%.
Impact of Heating
- Heating the cabin in cold weather has a more dramatic effect on range. Using traditional resistive heaters without heat pumps can reduce range by up to 50% in sub-freezing temperatures (below -10°C or 14°F), as heating requires significant electrical energy drawn from the battery.
- Heat pumps are a more efficient heating technology that can markedly improve cold-weather range. Studies show that EVs with heat pumps see only about an 8-10% reduction in range near 30°F (-1°C), compared to up to 26% increase in energy consumption with resistive heating.
- Some data examples include the BMW i3 losing 50% range with HVAC on in cold weather, versus a smaller 20% loss with HVAC off; the Chevy Bolt also lost 47% range with HVAC on compared to 10% loss with HVAC off in cold conditions.
Innovations to Mitigate HVAC Energy Impact
- Researchers are developing technologies such as a chemical heat pump combined with microwave energy (called an e-Thermal bank) that can store thermal energy more efficiently. This system aims to extend BEV range by up to 70% by reducing the energy lost to heating and cooling during extreme temperatures.
Summary
| HVAC Function | Temperature Range | Approximate Range Impact on EV |
|---|---|---|
| Air Conditioning | Moderate (below ~85°F/29°C) | Negligible to ~3-5% range loss |
| Air Conditioning | Very High (~40°C/104°F) | Up to 26-30% range loss |
| Resistive Heating | Cold (below -10°C/14°F) | Up to 50% range loss |
| Heat Pump Heating | Cold (~30°F/-1°C) | ~8-10% range loss |
In conclusion, HVAC systems can have a substantial impact on EV range, with heating in cold weather being the more critical factor. Efficient heating solutions like heat pumps can significantly reduce this range penalty. Cooling generally has a smaller impact unless in very hot climates. Advanced thermal energy storage technologies under development promise further improvements to range by mitigating HVAC energy demands.
Original article by NenPower, If reposted, please credit the source: https://nenpower.com/blog/how-does-the-use-of-hvac-systems-in-evs-impact-their-range/
