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It's all about charger coverage. As a large group we rented 2 Volkswagen ID.4's in Norway over the Christmas holidays (think -4 degrees F so we were getting abo

It's all about charger coverage. As a large group we rented 2 Volkswagen ID.4's in Norway over the Christmas holidays (think -4 degrees F so we were getting about half the advertised range) and it was never a limiting factor. Anywhere we went we could top up, from the grocery store down to the cabin that was quite out in the boonies, never had to fight for a charger spot either.

WarOnPrivacy 3y ago
> -4 degrees F so we were getting about half the advertised range Does this mean the electricity you paid for went half as long? (ev exp is ltd bc my cars are 30y-60y)
- jonasdegendt 3y ago
  > Does this mean the electricity you paid for went half as long? No, the battery simply isn't able to hold as much energy because the chemical process that makes it work "slows" down (my basic understanding of electrons, someone feel free to correct me).
- c0nfused 3y ago
  At cold temps you lose range a few different ways: First heat in an EV isn't free, this is usually where it gets you. People get in go "oh man its cold" and crank up the heat and there goes range. When you see one of the "this person ran out of power waiting in line at the Tesla charger in winter time" pictures this is how they did it. Second battery efficiency goes down. Finally, the battery usually is constantly doing the regen breaking thing but in cold weather it doesn't to save pack wear until you get the pack warm again
  - Scoundreller 3y ago
    Shouldn't a couple regen braking events be capable of dumping a boatload of heat?
    - amluto 3y ago
      At least last time I checked, Teslas had rather anemic battery heaters. IIRC they’re around 6kW. 6kW is not enough to make a big dent in required mechanical braking, and it’s also not enough to quickly heat the battery pack, especially when operated intermittently.
      - gnicholas 3y ago
        I thought GP was referring to generating heat for HVAC, which is an interesting idea. I assume one challenge would be getting the warmth from the brakes to the cabin.
        Scoundreller 3y ago
        Yeah, from what I've read, Tesla max regen is 60+kw. Does it just lockout regen braking until the battery pack is "receptive"?
        amluto 3y ago
        It limits max regen power, and the limit is variable. There’s a cute little indicator on the dash.
        amluto 3y ago
        A gadget to recover heat from a disk brake would certainly be interesting, but it sounds complex, messy and expensive. A bigger battery/coolant loop heater sounds more straightforward — the mechanism to convert kinetic energy to current is already there.
    - ggreer 3y ago
      The problem is that cold batteries can't charge or discharge quickly. From the battery's point of view, regenerative braking is the same as fast charging (just for a very short period of time). When the battery is very cold (or almost full), Teslas regen as much as they can, then use the friction brakes to keep a consistent feel for one pedal driving. The battery does have fluid pumped through it for heating/cooling, but it can take some time before the pack is warm enough to charge/discharge at its rated capacity. The longest I've had a cold battery notice is 20 minutes, and that was after my car sat at 0ºF overnight.
  - darkwater 3y ago
    I think you are missing the most important effect of cold: more air density at terrain level, which creates way more drag on the car.
    - ghaff 3y ago
      I very much doubt this. I've never seen this having a notably measurable effect on ICE vehicles in Massachusetts winters (which can be cold but aren't notably arctic).
      - darkwater 3y ago
        Because ICE vehicles don't have "range issues" so you just don't notice it.
    - ggreer 3y ago
      The density of air at 20ºC (293ºK) is 1.204kg/m^3. At -10ºC (263ºK) its density is 1.341kg/m^3, or 11% denser. For a Model 3 moving at 100kph, about half of its power is used to overcome air drag and half is used to overcome rolling resistance. Air drag is 1/2 * density * velocity^2 * coefficient of drag * area, so an 11% increase in density means an 11% increase in drag, so a ≈5.5% decrease in range. That's significantly less than typical cold weather range loss. Most of the range loss comes from climate control. In a combustion car, the majority of the energy in the gasoline is turned into heat. In cold weather, you just dump some of this heat into the cabin to keep it warm. An EV's efficiency is a disadvantage in this case, as it needs to use energy from the battery to heat up the cabin.
      - darkwater 3y ago
        Everything sum up. I don't have the exact numbers there but the HVAC system should draw ~2kW at full throttle. Giving an average of, let say, 160Wh/km (speaking of a recent Tesla M3 for example) at highway speed. Over an hour of full throttle heating you would have consumed in heating an extra ~10% of what you spent to move the car. So OK, maybe air drag increase is not the worst offender here but it's not just the HVAC system. ... While writing this I searched a bit and according to this [1] when there is really cold temperature and the battery still haven't got warm, it can draw 5-6kW at the beginning. Anyway when driving motors heat up, the heat is used to warm the battery, the battery heats up as well and all that heat is used by the heat pump to warm the inside of the vehicle. [1] https://insideevs.com/news/452464/tesla-model-y-heat-pump-system-details/ https://insideevs.com/news/452464/tesla-model-y-heat-pump-sy...
- Kirby64 3y ago
  Yes. You use twice as much electricity to go the same distance. Gas cars lose efficiency in the cold too, but it’s less drastic. Only stats I can find are 15% loss at 20F (which is a lot warmer than -4F). Also, charging tends to be much slower in the cold as batteries need to be warm to accept full charge rate. If you’re cruising on the highway it’s usually not too bad, but if you start from an overnight stop and then try to immediately charge the car you could be waiting for the battery to warm up.
dev_tty01 3y ago
It is not about charger coverage. When I have a 7:00 flight after an all day meeting I don't want to or can't budget the time required to fully charge an EV on my way to the airport. It's all about time.
- avhon1 3y ago
  That's about there not being a charger in the lot that the rental company uses as a matter of course when rentals are returned to them.

WarOnPrivacy 3y ago

> -4 degrees F so we were getting about half the advertised range Does this mean the electricity you paid for went half as long? (ev exp is ltd bc my cars are 30y-60y)

jonasdegendt 3y ago
> Does this mean the electricity you paid for went half as long? No, the battery simply isn't able to hold as much energy because the chemical process that makes it work "slows" down (my basic understanding of electrons, someone feel free to correct me).
c0nfused 3y ago
At cold temps you lose range a few different ways: First heat in an EV isn't free, this is usually where it gets you. People get in go "oh man its cold" and crank up the heat and there goes range. When you see one of the "this person ran out of power waiting in line at the Tesla charger in winter time" pictures this is how they did it. Second battery efficiency goes down. Finally, the battery usually is constantly doing the regen breaking thing but in cold weather it doesn't to save pack wear until you get the pack warm again
- Scoundreller 3y ago
  Shouldn't a couple regen braking events be capable of dumping a boatload of heat?
  - amluto 3y ago
    At least last time I checked, Teslas had rather anemic battery heaters. IIRC they’re around 6kW. 6kW is not enough to make a big dent in required mechanical braking, and it’s also not enough to quickly heat the battery pack, especially when operated intermittently.
    - gnicholas 3y ago
      I thought GP was referring to generating heat for HVAC, which is an interesting idea. I assume one challenge would be getting the warmth from the brakes to the cabin.
      - Scoundreller 3y ago
        Yeah, from what I've read, Tesla max regen is 60+kw. Does it just lockout regen braking until the battery pack is "receptive"?
        amluto 3y ago
        It limits max regen power, and the limit is variable. There’s a cute little indicator on the dash.
      - amluto 3y ago
        A gadget to recover heat from a disk brake would certainly be interesting, but it sounds complex, messy and expensive. A bigger battery/coolant loop heater sounds more straightforward — the mechanism to convert kinetic energy to current is already there.
  - ggreer 3y ago
    The problem is that cold batteries can't charge or discharge quickly. From the battery's point of view, regenerative braking is the same as fast charging (just for a very short period of time). When the battery is very cold (or almost full), Teslas regen as much as they can, then use the friction brakes to keep a consistent feel for one pedal driving. The battery does have fluid pumped through it for heating/cooling, but it can take some time before the pack is warm enough to charge/discharge at its rated capacity. The longest I've had a cold battery notice is 20 minutes, and that was after my car sat at 0ºF overnight.
- darkwater 3y ago
  I think you are missing the most important effect of cold: more air density at terrain level, which creates way more drag on the car.
  - ghaff 3y ago
    I very much doubt this. I've never seen this having a notably measurable effect on ICE vehicles in Massachusetts winters (which can be cold but aren't notably arctic).
    - darkwater 3y ago
      Because ICE vehicles don't have "range issues" so you just don't notice it.
  - ggreer 3y ago
    The density of air at 20ºC (293ºK) is 1.204kg/m^3. At -10ºC (263ºK) its density is 1.341kg/m^3, or 11% denser. For a Model 3 moving at 100kph, about half of its power is used to overcome air drag and half is used to overcome rolling resistance. Air drag is 1/2 * density * velocity^2 * coefficient of drag * area, so an 11% increase in density means an 11% increase in drag, so a ≈5.5% decrease in range. That's significantly less than typical cold weather range loss. Most of the range loss comes from climate control. In a combustion car, the majority of the energy in the gasoline is turned into heat. In cold weather, you just dump some of this heat into the cabin to keep it warm. An EV's efficiency is a disadvantage in this case, as it needs to use energy from the battery to heat up the cabin.
    - darkwater 3y ago
      Everything sum up. I don't have the exact numbers there but the HVAC system should draw ~2kW at full throttle. Giving an average of, let say, 160Wh/km (speaking of a recent Tesla M3 for example) at highway speed. Over an hour of full throttle heating you would have consumed in heating an extra ~10% of what you spent to move the car. So OK, maybe air drag increase is not the worst offender here but it's not just the HVAC system. ... While writing this I searched a bit and according to this [1] when there is really cold temperature and the battery still haven't got warm, it can draw 5-6kW at the beginning. Anyway when driving motors heat up, the heat is used to warm the battery, the battery heats up as well and all that heat is used by the heat pump to warm the inside of the vehicle. [1] https://insideevs.com/news/452464/tesla-model-y-heat-pump-system-details/ https://insideevs.com/news/452464/tesla-model-y-heat-pump-sy...
Kirby64 3y ago
Yes. You use twice as much electricity to go the same distance. Gas cars lose efficiency in the cold too, but it’s less drastic. Only stats I can find are 15% loss at 20F (which is a lot warmer than -4F). Also, charging tends to be much slower in the cold as batteries need to be warm to accept full charge rate. If you’re cruising on the highway it’s usually not too bad, but if you start from an overnight stop and then try to immediately charge the car you could be waiting for the battery to warm up.

dev_tty01 3y ago

It is not about charger coverage. When I have a 7:00 flight after an all day meeting I don't want to or can't budget the time required to fully charge an EV on my way to the airport. It's all about time.

avhon1 3y ago
That's about there not being a charger in the lot that the rental company uses as a matter of course when rentals are returned to them.