i) Preheating the cabin from mains electicity, either predictively or through user command.
ii) Using heat pumps to scavenge and move heat around different parts of the car. If you’re early in a road trip you would have enough power in the battery to heat the car for a day or more. If you’re later in the trip there will be a lot of heat in the batteries and motors which can be shifted into the cabin. Similarly heat pumps can be used in reverse to scavenge heat from the cabin and frame to keep the batteries warm if the car is left outside for a long time without being plugged in. Batteries don’t like dropping beneath a certain temperature range.
iii) Simply increasing heat insulation. It’s not difficult to insulate better, it’s just it hasn’t been needed, because there’s so much wasted heat energy in internal combustion vehicles. A human is a 100W space heater, I’d imagine you could quite easily design a cabin for a small car to hold temperature even in the absence of any other heat source.
In my experience most cars do hold temperature for at least 20-30m with vents closed. You still need air exchange though for longer periods, so losing heat is unavoidable.
edit: Ok here we go - Model 3 users report using about 240 to 300 watt-hours per mile. So I think that means a 1KW heater for an hour is equivalent to about 3 or 4 miles of range.
Still, that just means you want to limit your -10 degree trips to like 2.5 hours instead of 3 hours, and only if you don't have access to superchargers.
Besides, how is this different than a gasoline-powered vehicle? In your situation, you'd still be reducing your range by X% in order to survive N hours in case something happens- your gas tank is not infinite, after all. I suppose you could make the case that you currently have more refueling options than recharging options, but I don't think it will always be that way, and it's not currently that was in some locations, such as Norway.
My gas car has a 700mi range so its simply not an issue as I tend to not drive that long on a day trip. I have the X% fuel spare for N hours of emergency heating so long as I do say < 600mi/day. I can drive indefinitely in my gas car while keeping the fuel meter over half tank and that doesn't cause any inconvenience in terms of extra stops. Doing that with an EV (never going under say 50% charge) would be inconvenient.
The same would be true for battery cars once the range is enough. And the problem of course would exist for an ICE car with a shorter range.
The heater also can't be as complex as a plug-in-hybrid, requiring expensive serveice etc. It needs to be cheap, dumb, optional (so you only waste the cargo space on extreme long journeys and in cold weather) etc.
What I'm picturing isn't a complex system. It's a camping burner with a hose to the car's ventilation system. Think < 1cubic feet and sub $1k.
Now, I am not sure how much reserve heating you want, but it’s much closer than 10x cost wise.
So a 1KW heaster for 4 hours would lose you 16 miles of range.
Edit: and yes as was pointed out in another comment - heat is "free" while driving because of losses in the engine.
- How can I ensure I waste as little range as possible on heating, so that I don't risk having to make e.g. 2 stops instead of one?
- More critically, if I get stuck in traffic for several hours because of an accident, I need some way to ensure I don't freeze to death in my EV as I'm standing still and the battery runs out.
It seems these two things should be solvable with a single solution: a plug-in space heater to be used in emergencies and for maximizing cold weather range. The space heater could be e.g. a kerosene burner or similar. But for best effect it should of course "plug in" to the car vents.
Is this a thing? Or is heating the passenger compartment such a trivial use of energy anyway if the car is insulated, that it doesn't make a difference? In a concrete scenario: If I drive a model 3 and have 100km battery left, and I have 20km to my planned charging stop half way through my journey. Suddenly traffic stands still because of an accident and it's freezing outside. How long will the "100km" charge maintain the 30K temperature difference while still having 20km left?