Heat pump maximises winter range

An innovative heat pump system, deployed in Kia and Hyundai’s global EV line-up, maximises range in low temperatures.

It scavenges waste heat to warm the cabin without significantly impacting electric driving range.

The technology was introduced in 2014 on the first-generation Kia Soul EV. Comprising a compressor, evaporator and condenser, the heat pump captured waste heat from the vehicle’s electrical components, recycling this energy to heat the cabin more efficiently.

It meant the Soul EV’s 180km range from its 30kWh battery pack was protected in cold weather, but now the latest EVs from Kia and Hyundai offer twice the driving range and battery capacity – the second-generation Soul EV able to do 386km on its 64kW battery due to the upgraded heat pump.

The new system scavenges waste heat from an increased number of sources such as the battery pack and slow charger for optimum cold-weather EV range.

These innovations mean that Kia and Hyundai EVs offer more consistent range in temperatures where other EVs start to see a decline in the distance possible from a single charge, Kia says.

The Kona Electric proved this in a recent test in Norway, while a study by Korea’s Ministry of the Environment on the Hyundai Kona Electric and Kia Niro EV found the heat pump significantly reduced battery consumption in cold conditions, it adds.

The Norwegian Automotive Federation (NAF) compared 20 EVs in cold and warm weather conditions to identify models with the most consistent driving range and charging performance.

The Kona Electric topped the table, travelling 405km in the cold – compared to the 449km quoted under WLTP combined cycle testing conditions (23°C). In severe cold weather, the Kona Electric offered 91% of its WLTP combined cycle range, deviating just 9% from its claimed electric driving range.

The system uses the heat generated by source components to vaporise refrigerant from liquid to gas form. High-pressure gas is discharged from the compressor and forced into a condenser to be converted back into a liquid. This process generates additional heat energy that is recovered by the heat pump and used to warm the cabin.

This captured energy improves the efficiency of the heating, ventilation and air conditioning (HVAC) system, recycling it to more efficiently heat up the cabin and minimise battery power consumption.

By reducing the load on the battery, the heat pump cuts energy consumption from the HVAC system, maximising range.

Kia and Hyundai continue to develop their heat pump technology to yield even greater improvements in energy capture and efficiency.

A water-cooling system for Kia and Hyundai’s EV battery packs, rather than conventional air cooling, has yielded further increases in range without increasing physical dimensions. This development means battery cells in Kia and Hyundai EVs can be packaged much more tightly, with water-cooling channels taking up less space than air-cooling channels, increasing battery density by up to 35%.

Under its Strategy 2025 plan, Hyundai aims to sell 670,000 battery EVs and FCEVs annually and become a top-three EV manufacturer by 2025.

Kia’s Plan S will see the brand’s line-up grow to 11 EVs over the same period.