Tesla Model Y - The Only Tesla With A Heat Pump

[prdude]

So silly question, but this is only a large improvement in winter if you heat the cabin, correct? Does this also have a large efficiency improvement if you don't use cabin heat? (Maybe to heat the batteries?)

I would think a heat pump system could indeed more efficiently warm the batteries and power electronics than the PTC heater

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[prdude]

For an EV using a heat pump with an all-positions cooling loop valve can reduce the overall weight. For instance it allows eliminating the HV PTC heater.

The PTC heater probably can't be eliminated, because heat pumps can't scavenge heat below certain ambient temperatures. However, the PTC could probably be downsized and would definitely come on much less often.

 

[TheCats]

Won't be nearly as effective on the Mach-e. Tesla's have induction motors to harvest heat from. the Perm magnet motors in the Mach-e don't generate as much heat so there is less to scavenge.

Induction motors are less efficient to power, but have much lower freewheeling losses. PM motors have more coasting drag. Teslas (and most other EVs with AWD) use front induction motors and rear PM motors, omitting the front motor for low-end RWD models.

As for the minimum effective temperature, the home heat pump rule-of-thumb of 32F / 0C doesn't apply. First, it's old info with modern home pumps being effective down to about 0F. And even then the problem isn't that the heat pump isn't more efficient, it's that it can't provide enough heat to keep the house warm.

Second, this is an automotive environment. There is residual heat and waste heat from various sources, if the coolant system can make use of it. And the keep-from-freezing heat need is modest, allowing effective heat pump operation down to very low temperatures.

Heat pumps are an efficiency win across the board.

 

[TheCats]

The PTC heater probably can't be eliminated, because heat pumps can't scavenge heat below certain ambient temperatures. However, the PTC could probably be downsized and would definitely come on much less often.

The temperature is very low, much lower than would be commonly seen.

In that rare situation, Tesla eliminates a separate resistive heater by applying rotor-locking power to the motor, and then extracting that heat using the heat pump. You could do that without a heat pump, but it would require much more power since the motor is uninsulated.

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