4 ms·

When the battery is also powering your car’s heater the range drops significantly. Especially with short trips that need to repeatedly warm up from cooler winte

by koolba 6y ago

When the battery is also powering your car’s heater the range drops significantly. Especially with short trips that need to repeatedly warm up from cooler winter temperatures.

rsj_hn 6y ago
I think in a real winter the battery would need to be heated even when the car is parked overnight, no? Or store it in a well-heated garage overnight.
- jeffrallen 6y ago
  Nope, I walked outside in -10 degrees centigrade and had to choose between my diesel Sharan and my Renault Zoe. Easy choice: the Zoe had instant heat because of its heat pump. It worked fine even with with battery at -10, and the displayed range slowly rose, as the battery warmed up. Once the interior was comfortable, the BMS asked the heater to send some heat into the batteries. In the Zoe's air cooled batteries, the heating/cooling system is shared between the occupants and the BMS.
abfan1127 6y ago
why not use a heat pump for heating given its >100% relative efficiency? Edit: apparently some VW models include a heat pump for this reason.[1] Edit 2: Apparently some Teslas have it too. [2] [1] https://www.speakev.com/threads/heat-pump-yes-or- https://www.speakev.com/threads/heat-pump-yes-or- no.16768/ [2] https://electrek.co/2020/03/13/tesla-model-y-has-a-heat-pump-for-consistent-range-in-cold-climates/ https://electrek.co/2020/03/13/tesla-model-y-has-a-heat-pump...
- X6S1x6Okd1st 6y ago
  Where are you pumping the heat from?
  - abfan1127 6y ago
    outside, just like residential heat pumps.
  - emkoemko 6y ago
    yea but many places in winter heat pumps efficiency goes to basically a electric heater level and if works at all.
    - pcdoodle 6y ago
      Not true. Inverter heat pumps can do 8 or more btu per watt at sub zero temps.
    - nnevod 6y ago
      IIRC, cold climate specific (Mitsubishi Zubadan series for example) have COP of about ~2 at -20C. Even cheaper cold climate pumps do function at -30, albeit with COP barely above 1. So resistive heater should also be present, but it won't be used often.
- nnevod 6y ago
  In my opinion, proper winter-ready BEV should have a heat pump for heating the interior and battery, battery insulation to reduce uncontrollable loss of heat from battery, rotary heat exchanger to further save on heating ventilation air and double-pane windows to reduce losses from interior. Double-pane windows would increase weight by about 5%, while decreasing losses through windows about 5x, iirc.

by koolba 6y ago

When the battery is also powering your car’s heater the range drops significantly. Especially with short trips that need to repeatedly warm up from cooler winter temperatures.

rsj_hn 6y ago

I think in a real winter the battery would need to be heated even when the car is parked overnight, no? Or store it in a well-heated garage overnight.

jeffrallen 6y ago
Nope, I walked outside in -10 degrees centigrade and had to choose between my diesel Sharan and my Renault Zoe. Easy choice: the Zoe had instant heat because of its heat pump. It worked fine even with with battery at -10, and the displayed range slowly rose, as the battery warmed up. Once the interior was comfortable, the BMS asked the heater to send some heat into the batteries. In the Zoe's air cooled batteries, the heating/cooling system is shared between the occupants and the BMS.

abfan1127 6y ago

why not use a heat pump for heating given its >100% relative efficiency? Edit: apparently some VW models include a heat pump for this reason.[1] Edit 2: Apparently some Teslas have it too. [2] [1] https://www.speakev.com/threads/heat-pump-yes-or- https://www.speakev.com/threads/heat-pump-yes-or- no.16768/ [2] https://electrek.co/2020/03/13/tesla-model-y-has-a-heat-pump-for-consistent-range-in-cold-climates/ https://electrek.co/2020/03/13/tesla-model-y-has-a-heat-pump...

X6S1x6Okd1st 6y ago
Where are you pumping the heat from?
- abfan1127 6y ago
  outside, just like residential heat pumps.
- emkoemko 6y ago
  yea but many places in winter heat pumps efficiency goes to basically a electric heater level and if works at all.
  - pcdoodle 6y ago
    Not true. Inverter heat pumps can do 8 or more btu per watt at sub zero temps.
  - nnevod 6y ago
    IIRC, cold climate specific (Mitsubishi Zubadan series for example) have COP of about ~2 at -20C. Even cheaper cold climate pumps do function at -30, albeit with COP barely above 1. So resistive heater should also be present, but it won't be used often.
nnevod 6y ago
In my opinion, proper winter-ready BEV should have a heat pump for heating the interior and battery, battery insulation to reduce uncontrollable loss of heat from battery, rotary heat exchanger to further save on heating ventilation air and double-pane windows to reduce losses from interior. Double-pane windows would increase weight by about 5%, while decreasing losses through windows about 5x, iirc.