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Comment by filleokus | Hacker News Reader

Does heating in internal combustion engine cars really affect fuel consumption? My assumption was that most cabin heat was waste heat from the engine, that would otherwise be vented out? Given the dismal efficiency of ICE, shouldn't it be enough to keep a cabin warm even in quite cold climates?

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The engine by itself produces a lot of waste heat. But modern engines are more efficient and take a while to warm up (especially diesels, but small turbos like Honda 1.5 too) so cars sometimes implement resistive heating to heat the cabin quicker.

Also some cars have independent heating that can be used to heat up the car up without running an engine. Not sure how exactly it works but I think it uses special battery.

AC compressor of course takes a lot of power.

Which ICE cars use resistive heating? I've never seen an alternator large enough on an ICE car to do it. (I'm also skeptical of how well that'd work on a 12v electrical system)

Hybrids will commonly have them so they can run climate control independent of the engine (at least until the HV battery gets too low) and also bring coolant temp up faster. It seems like they are usually called the PTC heater or supplemental heater.

Ford also seems to offer them as an option (e.g. as part of the cold weather package)for a number of their straight ICE vehicles like the Bronco sport, Escape, or F-150.

See this https://shops.audi.com/en_GB/web/zubehoer/p/retrofit-solutio... for example. I can only assume it's resistive, since it doesn't start the engine - but it might be a system for running the AC heatpump without engine, maybe. Also now that I think of it, window defrost is resistive.

I would guess system like this would be rare in US, because you are allowed to have remote start on your cars.

edit: never mind, it burns fuel https://www.auditech.org/acont-1427.html

Electric window defrosters are really low wattage - because its just trying to raise the temperature of the surface of the glass by a few degrees. Generally IIRC no more than 25-30a - which is a fair bit on a car with a 100a alternator - but less than for example the blower for the air conditioner.

I never thought I'd see the return of the gasoline heater. I wonder if its offered in the states.

Block heaters can be used to heat the engine coolant (and afterwards the cabin) with or without running the engine. I doubt any cars have special batteries for these (even a drive battery of a non-plugin hybrid is somewhat small to be useful); block heaters that don't require external electricity simply use the car's fuel in an auxiliary burner.

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