The problem with thermal insulation of the battery enclosure is that you want the battery to cool towards ambient in most conditions, so if you use ambient air cooling only [as the LEAF does], you probably don't want to do much thermal insulation for the rare times when it's below -20°C. Most EVs have a more active cooling solution, which could allow for thermal insulation of the pack while still having adequate cooling via a water/coolant loop.
In an EV this would be handled when charging by running a heater until it is a safe to accept charge. When driving, any time the battery becomes too cold you would divert regenerative braking energy into heating the batteries instead.
The reason is that pulling ~10A or so causes enough resistive heating that the battery voltage will go *up* over that time, and allow the lead-acid battery chemistry to work better when you throw a couple of hundred amps of starter motor across it.
Edit: typo
2) you don’t need to keep them warm 24/7, just above freezing when charging them or and/or when you want more efficiency or maximum power (like a longer trip, or midway through a drive).
ICE engines are quite inefficient when ‘cold’ (and diesel may refuse to run at all), this isn’t a new problem.
The batteries don’t need to be warm by human standards, and the vehicle will still work even when quite cold, just not very well.
ICE engines definitely have their own set of cold-related issues, but I can't imagine heating a 150 kg engine block would require the same amounts of energy required to heat 500 kgs of battery twice (charging and before driving).
Mind you, I'm not arguing against EV's or anything; I'm just saying it sounds like there's an engineering problem that needs to be solved before EV's can replace ICE cars in very cold climates, which incidentally, also tend to be where the most range is needed.
Feel free to do the energy calcs - there is no engineering challenge here for EVs that is currently unsolved.
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.
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.
Might pose a problem during heavy discharge with 105F ambient temps?