I prefer practical tests. Right now, however, the authorities here encourage people to avoid using electric pre-heaters in order to save electricity, so I'll take your word for it. :)
Ideally, things like this wouldn't be a problem, but where I live EV's is simply not an option during winter. Charging from a regular 240V/16A outlet takes too long, the nearest proper charging station is over 25km away, and the grid out here won't handle the load of everyone getting proper chargers at home. Adding additional load to heat batteries of thousands of cars probably won't be a viable option until the grid has been modernized.
Luckily, this shouldn't be a problem in warmer, more densly populated areas anyway. Better to roll out EV's where it's viable, and sort out the fringe cases later.
Assuming Cp = 0.32 kJ/kg•K, which seems about right, you’re talking about 3kwh to heat up a 75kwh sized pack from -25C (-13f) to 25C (77f), or about 4% of the pack capacity. Which about lines up with my experience ‘warming up’ ICE vehicles. It’s not great fuel economy wise to do so.
If you have a block heater, seems like those can be as much as 750-1500 watts. If a diesel, that block needs to get pretty warm, and it’s not like a ton+ of steel/cast iron doesn’t take a lot of energy to heat up either. And that’s ignoring transmission heaters, battery heaters, etc.
Is it 3kwh worth? That would depend on a lot of factors not specified, but it wouldn’t surprise me if it was close.
A 240V/16A outlet (16A is a bit unusual? Usually it’s multiples of 5), is 3.8KW Peak.
That would indeed be limiting, as assuming something like
90% efficiency a full charge is 20+ hours.
It’s an odd number to pick though, as unless someone has a very undersized utility feed, more shouldn’t be a big deal?
I know, some places have only a 50 amp panel and blow fuses anyway, but compared to buying a new car that’s a cheap problem to fix. Even a not shitty welder is going to want 240v/20A, and an old 50 amp panel can barely handle a space heater and other usage.
A typical electric stove is 240v/30A (or more) same with an electric dryer or AC.
If using a typical electric dryer type connection, that’s 7200 watts, and at 90% efficiency could recharge a fully discharged 75kwh pack in 11 hrs, which is ‘overnight’ in most situations.
Most newish residential construction has 150 or 200 amp, 240v split phase service and panels, or 36-48kw, which provides a lot of headroom.
Of course to your point, out in the sticks things are different, and I don’t know your situation or the local counties power infrastructure.
Just supply chain issues would be a show stopper for me in a remote area. Couple in frequent power outages and that it could be life threatening not having a vehicle during one, also an issue.
Most of the grid here was built with Marshall plan money after the war and has barely been touched since. Renovations are under way but will take another decade or so. And yes, outages are frequent.
Yeah, and some areas are remote enough it will be multiple decades.
Even phasing out propane heat is likely to take several generations (if ever).
My point was more that I don’t think it’s an engineering problem anymore. The direct problems there have been solved.
It’s more of an infrastructure/capex one, and the economic pressure to change or not is often about the economic cost of various options like the ratio of the price of a gallon of diesel to a kwh.
And it’s not looking as favorable towards ICE as it used to be.
Feel free to do the energy calcs - there is no engineering challenge here for EVs that is currently unsolved.