Forums

Cold weather range loss

Cold weather range loss

Does anybody else notice that M3 actual range drops by as much as 40% when temps drop into the 20s Fahrenheit? Is the heater the culprit? Wh/mi on my normal commute is about 215 in 65 degree weather and about 290 in 25 degree weather.

Joe M | 16 novembre 2019

Capacity wise exactly the same as the resistance heater

7*3412 or 23898 btu or if you like the term 2 ton

Physical size wise

Depends on the trade off of efficiency vs ability to handle road dirt, ability to clean, the amount of fan noise deemed acceptable etc. The average 2 ton high efficiency heat pump coil is about 15 sq feet. If you accept a roaring fan or accept a coil that would have to be cleaned regularly you could shrink it significantly. Still unless you got some really good tricks not a real good fit in the aerodynamics of the car.... which I noted previously.

Magic 8 Ball | 16 novembre 2019

Yes, I meant physical size, of course. I suspect the heat exchangers would have to be much larger than is practical for fitting in the car. The EV design for all this Pre-heating stuff is great if the car is plugged in. If the car is out in the cold, unplugged, I really don't see how a heat pump, that does not take up a bunch more room) works in a car unless (as has been pointed out) you are in a climate where the delta T you are dealing with is small and above a certain lowest temperature that is much higher than a resistive heater can handle.

kevin_rf | 16 novembre 2019

Btw. An interesting graph that shows why heat pumps in houses can not keep up when the temperatures drop to low. As temperature drops, the pump cannot produce enough BTU's to meet demand.

https://asm-air.com/dashboard/static/uploads/0b9861e04d78c15702a52d44234...

From an article trying to sell you heat pumps
https://asm-air.com/heat-pump/what-temperature-is-a-heat-pump-not-effect...

Btw. No reason why the Model 3 ac system could not be reversed to as act as a heat pump. Many residential ductless systems do. I know the Fujitsu we have installed does. I often use it to warm the office in the winter and the wife wastes electricity with the AC function in the summer.

Pages