Tesla last week outlined some of the details that characterize its heat pump system, which is now featured across its vehicle lineup
The electric vehicle maker claims its design performs well in very cold weather where other heat pumps fail
Depending on the exact situation, Tesla claims its cars with the heat pump system could use just a quarter of the energy than without to keep the cabin warm. Overall, this can result in up to 20% less energy use when driving in cold weather, Tesla says — although it’s unclear if this relates specifically to in-cabin energy use.
Tesla is far from the only automaker finding relief in heat pumps EV range loss in cold weather. It resisted technology years ago
Prior to the heat pump, Tesla had a strategy of using waste heat from the engine and power electronics to warm the battery and claimed to increase range in cold weather without the added complexity of a heat pump. But the company changed its mind with the heat pump, which made its debut in the Model Y
Tesla heat pump
Tesla heat pump
Tesla heat pump
The answer seems to be that it found a way to make addition less complex. It designed what they called a Super Manifold, which brings together all the refrigerant passages and coolant passages that could otherwise be separate components. As explained in this video, Tesla has integrated the heat pump with an “octovalve” that rotates to a different position depending on the operating mode, rather than redesigning the coolant loop.
(embed)https://www.youtube.com/watch?v=DyGgrkeds5U(/embed)
How heat pumps work
The Tesla video points out that heat pumps are a bit like building air conditioners, moving heat from a cooler environment (inside) to a warmer environment (outside), only the opposite
Unlike internal combustion engine vehicles, electric vehicles do not have an engine that emits waste heat that can be used to heat the interior. Resistance heating, such as that used for space heaters, toasters or hair dryers, takes a lot of energy out of the range
Heat pumps move heat rather than create it, and the physics can sound almost magical: A carefully chosen gas — a refrigerant — extracts heat from its surroundings when it’s compressed into a gas, and then releases heat when it condenses back into one liquid
Tesla Model S Plaid heat and heat pump
Heat pumps are one of the keys to reduction EV range loss in cold weather because of this energy calculation. On an energy-in-energy-out basis, according to Bosch, one of the manufacturers of heat pumps, a heat pump with an output of 1 kW produces a heat equivalent of 2 to 3 kW. Mahle, another supplier, says its heat pump can recover 20% of the cold-weather zone loss.
There are some caveats to this. Heat pumps come with many additional costs and complexities; they can create noise that interrupts the silent EV experience; and they often don’t provide the quick results that resistive heating does. So owners may only see the payoff in efficiency on longer road trips – when they help increase range and make it easier to reach the next charger without sacrificing cabin comfort
Necessary part to avoid winter doldrums
Businesses are increasingly coming to the conclusion that the trade-offs are worth it. General Motors, for example, has emphasized that the real benefit is behind why they chose to include it Heat pumps in all upcoming GM EVs.O
There are new ways to configure the system, especially for cold weather wins. Rivian is there Redesigning its thermal system to integrate a heat pump, and lately Heat pump for Hyundai and Kia modelsHeat dissipated from a number of drive components helps turn the liquid refrigerant back into a gas, reducing its stress and increasing energy efficiency
Systems that have a heat pump combine it with a resistance heater to quickly mist/defrost the windshield and quickly heat the cabin when needed, then hand the baton over to the heat pump when it can. As the wiring diagram for the system in the Toyota Prius Prime points out, they can get very complex.
Toyota Prius Prime heat pump
This isn’t the first sighting of Tesla’s heat pump design. In 2020, Munro & Associates manufacturing expert Sandy Munro, known for his teardown insights, released a video about the new component.O
Tesla’s own design wasn’t entirely flawless either. The company needs to fix an issue with an improperly working heat pump valve that is causing the system to become depleted of refrigerant and possibly fogging up the windows. This Recall for Tesla heat pump Campaign affecting nearly 27,000 2020-2022 model year vehicles has been addressed with an over-the-air update
