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Comment by NeoTar | Hacker News Reader

> EV performance is horrific in cold conditions.

If anyone knows about it, I'd be interested to explore this further.

My understanding is that in some parts of Canada it's common to plug your currently petrol/diesel car into an electricity socket overnight to provide a low-level of heating (otherwise the car would be impossible to start in the morning) - is this level of heating insufficient for an EV?

Alternatively how much electricity would be wasted spending some power to keep batteries at a warm enough temperature to prevent performance degradation when charging? Are we talking a few percent or a double/tripling of power costs?

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The problem is not keep the battery warm while parked, it's keeping the battery warm while driving. Most EVs can "preheat" themselves before you start in the morning, the smart one's might even learn the patterns and be ready when you get in at 07:30 every day.

The problem is that driving EVs in the cold costs a lot more energy. I've got a Ford Mustang Mach E for about 2.5 years now. In the winter the range that Ford claims drops by about 30 to 35%. That is a lot of range that goes missing just because the temp drops below 5 degrees Celsius.

Luckily I'm the perfect EV candidate: my daily commute is less than 50% of the total range so I can drive 2 days to the office if needed. And I can charge both at home and at the office.

The main problem that I see is that people cannot charge at home. If you are dependent on fast chargers by the side of the road you are going to have a hard time. The downtime for fast-chargers is enormous: my personal guess would be that they do not reach the 90% uptime. Which is bizar problem to have because a fast-charger and remote monitoring of the charger condition should be a solved problem by now.

  > The problem is that driving EVs in the cold costs a lot more energy. I've got a Ford Mustang Mach E

Nowadays this problem is mostly just the Mach E.

The Mach E delivers heat in the most inefficient way possible: resistive heat[0]. Modern EVs from other manufacturers use heat pumps, which are much more efficient. There's still some drop in winter range (like gas cars), but it's nowhere near 35% anymore.[1]

Ford's system is also Rube Goldberg[2]: they use a water-based PTC heater to warm a small isolated coolant loop (complete with its own separate reservoir!), and then run a pump to send it through a liquid-to-air heater core. Obviously done for commonality with an ICE heater core, but the unnecessary weight and complexity shows the compromises to shoehorn an electric drivetrain into a ICE (or even "flex") platform.

[0] https://www.youtube.com/watch?v=00ejq7z4H6g&t=449

[1] https://www.autoevolution.com/news/here-s-how-much-range-a-t...

[2] https://www.youtube.com/watch?v=m1kHsd3Ocxc

>My understanding is that in some parts of Canada it's common to plug your currently petrol/diesel car into an electricity socket overnight to provide a low-level of heating

Kind of. Block heaters help warm the engine coolant which warms engine and the oil, making it less viscous and help it flow properly so that the battery doesn't need to work as hard to crank the engine. They're typically only 400w to 600w draw.

Modern full synthetic oil and a well maintained AGM battery makes it less necessary, it's just a little less wear on the engine overall over the long term. Most folks though don't spring for either since they're a bit more expensive then mineral oil and flooded lead acid batteries.

Your comment is more about the 'passive' heating to keep some bare minimum for the hardware to function, but a big part is the 'active' heating for the driver and passengers.

If we look at the total energy consumption for driving in cold conditions, then moving the vehicle along the road needs in the ballpark a similar amount of energy as what is required to heat up the interior of the car to a reasonable temperature and keep it there - cars aren't (and probably can't be) as insulated as houses, so they need quite a lot of energy to stay so much warmer than the outside.

In an ICE, most that heating is done from waste heat of the engine. In an EV, that comes directly out of your range.

> In an ICE, most that heating is done from waste heat of the engine

I don't think there is a car in production where the heating is coming not from the engine.

Some cars do have additional resistive heating or heat pumping through AC, where that is technically driven by engine power, but not from the waste heat.

Implied "mass market, passenger".

Of course there are some cars which do have a resistive heating, but which are those?

> heat pumping through AC

Uhm, the compressor runs from the engine so while the heat is not from it, it's still directly relies on availability of running engine.

The small diesels like VW Polo etc have resistive heaters as otherwise it would take too long for comfort to heat up the cabin.

Also don't forget that seat heaters are also resistive and most cars in cold climates have them.

> Also don't forget that seat heaters are also resistive and most cars in cold climates have them.

I know it (or more like my bum) too damn well, though I didn't think about them in this case.

> small diesels like VW Polo

Makes sense, though as I understood, it's strictly auxiliary till the engine is heated aaaand maybe some additional heating at the parking lot with the engine turned off, though I would wary of this usage, it would drain even the extended battery fast.

Overall it's not quite what I had in my mind (think of space heaters), though yes, there are some parts which can operate independently from the engine, though it's not a primary function for them.

Thanks for the hint.

There's also these https://www.disco3.co.uk/wiki/Fuel_Burning_Heater that can be run with the vehicle engine off.

In any case, the key point is that in an ICE car the heating is mostly "free" since the engine has perhaps 40% efficiency and the majority of heat released by combustion is unused/unusable waste heat that might as well be used to heat up the car if you need to, but in an EV you don't have that source of free waste heat to tap into, and you have to use the energy that you could have used for moving the car instead.

Yes in our experience, a 120V outlet is sufficient to keep the EV battery warm when the outside temperature is -30C. However, that's all it can do; it won't add any appreciable charge to the battery while it is doing so.

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