5 ms·

I think the issue in cold climates is not the battery itself, it's heating the cabin. With a combustion engine you use waste heat, but with a battery engine yo

by ars 8y ago

I think the issue in cold climates is not the battery itself, it's heating the cabin. With a combustion engine you use waste heat, but with a battery engine you use resistive heat and that comes right from your battery. A/C also uses battery, but heat uses more energy.

goodcanadian 8y ago
A/C also uses battery, but heat uses more energy. I can't speak for all cars, but mine uses a heat pump for heat. Should have similar efficiency to A/C as that is exactly what a heat pump is.
- Scoundreller 8y ago
  Their efficiency goes way down the colder it gets. They’ll work well at 5-10C, but frost up and require electrically-expensive defrost cycles when it’s colder than -2 or -3 C.
- tigershark 8y ago
  Heat pump with outside temperatures below zero has same or lower efficiency than resistive heating.
  - Faaak 8y ago
    I suppose the cars heats resistively below zero, and with a heat pump above
  - g8oz 8y ago
    A modern heat pump with a variable speed compressor can be more efficient than resistive heat down to about -25 degrees Celsius (-13F). See Mitsubishi's Mr. Slim series. http://cdn.agilitycms.com/mesca/productdownloads/mem-201806-e-p-series.pdf http://cdn.agilitycms.com/mesca/productdownloads/mem-201806-... (page 13)
    - tigershark 8y ago
      And if you use a ground source heat pump (that has to be interred) it would be even more efficient. So? I don’t think that you can put either of them in a car...
      - g8oz 8y ago
        The offerings from Mitsubishi and similar ones from other Asian manufacturers like LG and Fujitsu are air source heat pumps. I see no reason why the tech can't be scaled down to fit a car. It's certainly a reasonable goal for auto parts suppliers to aim at.
p1mrx 8y ago
Some EVs produce heat more efficiently using a heat pump, which is basically an A/C running backwards.
- xxs 8y ago
  this works at 3-4C, falling down the efficiency drops off rapidly. House geothermic heating is very similar, except the collector is buried under the ground where the temperature doesn't really go negative C (until -30C and depends on the soil, etc). Overall for EV cars in cold winters producing heat is a non-trivial task.
  - olivermarks 8y ago
    IC engines drive all associated 'accessories' via belts where EV has to have dedicated battery draining motors for everything from windscreen wipers to hvac
    - Rinzler89 8y ago
      That's not completely true. For fuel efficiency, most modern ICE cars drive all the accessories with electric motors, with only the AC and brake booster being powered by the ICE in some cases.
      - olivermarks 8y ago
        Alternator charges battery
Scoundreller 8y ago
Recommendation #1: heat the occupant, not the cabin Recommendation #2: pre-heat the cabin Recommendation #3: if/when driving in stop&go traffic, use the regen energy directly for heating to save some charge/discharge cycles. Recommendation #4: along with #2, use some phase change materials to “charge” some thermal batteries. #1&2 are a thing. Not sure about 3 and 4. 3 may require some predictive modelling to know if you’ll be driving in stop&go or not.
- icebraining 8y ago
  How is #1 done?
  - Scoundreller 8y ago
    Heated seats and steering wheels.
  - jusssi 8y ago
    With a seat heater. They were popular in the old times, when engines were not digitally controlled and took a long time to heat up enough to provide any warming effect inside the car.
    - LinuxBender 8y ago
      Also heated thermal underwear [1] [1] - https://www.amazon.com/J-Jinpei-Lightweight-Intelligent-Temperature-Rechargeable/dp/B07HRHJBNQ/ref=sr_1_2?ie=UTF8&qid=1546459920&sr=8-2&keywords=heated+thermal+underwear https://www.amazon.com/J-Jinpei-Lightweight-Intelligent-Temp...
  - avar 8y ago
    With clothing.
  - baroffoos 8y ago
    Dress properly for the weather.
  - 8y ago
londons_explore 8y ago
Heat pumps can be used to heat the cabin with far less energy than resistive heaters. It's tricky to design them to be cheap, light, and work all the way down to -30C and up to 60C that cars are expected to be able to work in.

by ars 8y ago

goodcanadian 8y ago

A/C also uses battery, but heat uses more energy. I can't speak for all cars, but mine uses a heat pump for heat. Should have similar efficiency to A/C as that is exactly what a heat pump is.

Scoundreller 8y ago
Their efficiency goes way down the colder it gets. They’ll work well at 5-10C, but frost up and require electrically-expensive defrost cycles when it’s colder than -2 or -3 C.
tigershark 8y ago
Heat pump with outside temperatures below zero has same or lower efficiency than resistive heating.
- Faaak 8y ago
  I suppose the cars heats resistively below zero, and with a heat pump above
- g8oz 8y ago
  A modern heat pump with a variable speed compressor can be more efficient than resistive heat down to about -25 degrees Celsius (-13F). See Mitsubishi's Mr. Slim series. http://cdn.agilitycms.com/mesca/productdownloads/mem-201806-e-p-series.pdf http://cdn.agilitycms.com/mesca/productdownloads/mem-201806-... (page 13)
  - tigershark 8y ago
    And if you use a ground source heat pump (that has to be interred) it would be even more efficient. So? I don’t think that you can put either of them in a car...
    - g8oz 8y ago
      The offerings from Mitsubishi and similar ones from other Asian manufacturers like LG and Fujitsu are air source heat pumps. I see no reason why the tech can't be scaled down to fit a car. It's certainly a reasonable goal for auto parts suppliers to aim at.

p1mrx 8y ago

Some EVs produce heat more efficiently using a heat pump, which is basically an A/C running backwards.

xxs 8y ago
this works at 3-4C, falling down the efficiency drops off rapidly. House geothermic heating is very similar, except the collector is buried under the ground where the temperature doesn't really go negative C (until -30C and depends on the soil, etc). Overall for EV cars in cold winters producing heat is a non-trivial task.
- olivermarks 8y ago
  IC engines drive all associated 'accessories' via belts where EV has to have dedicated battery draining motors for everything from windscreen wipers to hvac
  - Rinzler89 8y ago
    That's not completely true. For fuel efficiency, most modern ICE cars drive all the accessories with electric motors, with only the AC and brake booster being powered by the ICE in some cases.
    - olivermarks 8y ago
      Alternator charges battery

Scoundreller 8y ago

Recommendation #1: heat the occupant, not the cabin Recommendation #2: pre-heat the cabin Recommendation #3: if/when driving in stop&go traffic, use the regen energy directly for heating to save some charge/discharge cycles. Recommendation #4: along with #2, use some phase change materials to “charge” some thermal batteries. #1&2 are a thing. Not sure about 3 and 4. 3 may require some predictive modelling to know if you’ll be driving in stop&go or not.

icebraining 8y ago
How is #1 done?
- Scoundreller 8y ago
  Heated seats and steering wheels.
- jusssi 8y ago
  With a seat heater. They were popular in the old times, when engines were not digitally controlled and took a long time to heat up enough to provide any warming effect inside the car.
  - LinuxBender 8y ago
    Also heated thermal underwear [1] [1] - https://www.amazon.com/J-Jinpei-Lightweight-Intelligent-Temperature-Rechargeable/dp/B07HRHJBNQ/ref=sr_1_2?ie=UTF8&qid=1546459920&sr=8-2&keywords=heated+thermal+underwear https://www.amazon.com/J-Jinpei-Lightweight-Intelligent-Temp...
- avar 8y ago
  With clothing.
- baroffoos 8y ago
  Dress properly for the weather.
- 8y ago

londons_explore 8y ago

Heat pumps can be used to heat the cabin with far less energy than resistive heaters. It's tricky to design them to be cheap, light, and work all the way down to -30C and up to 60C that cars are expected to be able to work in.