4 ms·

How do electric vechicles hold up in something like this?

by arberx 5y ago

grayfaced 5y ago
Not well, the heater is a major drain. If you stop the heater, the batteries get cold and perform significantly worse.
- s5300 5y ago
  I’m pulling this out of really old knowledge I’ve not looked over in years so may be incorrect… While you are right about “not well”, the other option can often be “not at all” The batteries used in most EV’s should always work to some degree, with regards to temperatures experienced on Earth - the batteries & other systems in most ICE can be completely crippled/not work at all under certain temps faced on Earth Now, you can specifically go out of your way to ruggedize all systems in your ICE so it works to a much better degree than the EV, but the average person is definitely not doing that.
  - kube-system 5y ago
    The saving grace with ICE is that they are so inefficient that they literally are mostly heat generators that also produce some mechanical force as a significant byproduct. They might not like starting in the cold, but once they're started, they're fine.
    - beerandt 5y ago
      There's similar efficiency losses for EVs, but (besides battery efficiency or thermal penalties) they're just further upstream.
- crooked-v 5y ago
  A heat pump system (such as in a Tesla Model Y or a Kia Niro) is significantly more efficient than a plain electric heater, though I haven't seen any hard numbers for cars with that equipment in winter weather.
  - dont__panic 5y ago
    Doesn't Tesla recommend that users use the heat as little as possible, and use the seat warmers instead, to conserve battery? Or has that changed in more recent models?
toomuchtodo 5y ago
If they’re not moving and have a heat pump, well, but like a combustion vehicle will exhaust their energy storage eventually. Resistive heat or suboptimal battery architecture? Poorly. Jerrycans for some, tows to Fast DC chargers for others. Class 8 semis should have sufficient diesel reserves for long loiters, even with truckers using auxiliary power units for heat. If not, it is trivial to refuel them on the road with a transfer pump.
- whoopdedo 5y ago
  Aren't EVs programmed to hold a reserve charge for emergencies? To avoid the cost and inconvenience of a tow, shut off power before you lose the ability to drive yourself to the nearest charger. (Bonus points for adjusting the threshold based on the distance to known stations.) But in the case that a car does drain the battery, how difficult is it to get a portable charger to someone? Have roadside mechanics started carrying generators in their trucks now? They probably should, with the appropriate cables.
  - toomuchtodo 5y ago
    To your first paragraph, yes, but battery charge can decline rapidly in the cold at low states of charge. You may exhaust the reserve depending on your circumstances. To your second paragraph, AAA (the tow service) piloted mobile generators for stranded EVs. There was no demand, and the service was discontinued.
  - fomine3 5y ago
    Unable to driving is better than freezing death by not using heater.
- trompetenaccoun 5y ago
  This is a misconception. Heat pumps can improve things a little but often far from as much as people expect. The problem is that in cold conditions most of the loss is from reduced battery performance right from the start. In really cold conditions it can be 50% and more reduction in battery performance. This is energy you're not getting back, heat pump or not. In addition the performance depends on the temperature. There is a sweet spot and the colder it gets from there the less effective it becomes. At around -20 degrees C and below it's effectively useless. There are already vehicles that have been tested in real world conditions. Tesla Model 3s exist with and without heat pump. The difference isn't that large, around 10% more range with the pump in perfect conditions. I've seen people doing tests sleeping in their cars all night and in cold North American winters it's not pretty. With a fully charged battery you will get enough heat for a comfy good nights sleep, 8 hours or so. So lets say in an emergency situation you can stretch it to 12 or so by reducing the temperature. But that's on a full charge! Most cars getting stuck in traffic are not going to have fully charged batteries. It absolutely is a problem with EVs even more than with ICE cars.
exhilaration 5y ago
A stranded ICE vehicle will exhaust its gas tank in 8 hours, max. You can turn it on an off to stretch it out but I wonder if you'll just burn more gas that way. Google (and Quora) suggests that a Tesla will last 36-72 hours, "or less" if it's very cold. I think EVs win in this case, assuming a full tank versus a full charge. Regardless if you're in a place where this could happen you should have a box of chemical handwarmers, a heavy blanket, food, water, and other stuff in a box for emergencies. Edit: looks like I'm wrong, much better answers below!
- relaytheurgency 5y ago
  Where are you getting the 8 hours from? A car that gets 30 mpg with a 14 gallon tank can _drive_ for nearly 8 hours at 60 mph. That same car may burn (on the highest end) 1/2 a gallon an hour idling which would be more than 24 hours of idling time.
- hotpotamus 5y ago
  8 hours seems quite quick. I've heard that the average car will idle for 2 days on a full tank, though I haven't tried it myself.
- BeefWellington 5y ago
  > A stranded ICE vehicle will exhaust its gas tank in 8 hours, max. You can turn it on an off to stretch it out but I wonder if you'll just burn more gas that way. Idling consumes little gas compared with actually moving the vehicle: https://www.energy.gov/eere/vehicles/fact-861-february-23-2015-idle-fuel-consumption-selected-gasoline-and-diesel-vehicles https://www.energy.gov/eere/vehicles/fact-861-february-23-20... A 4.2L engine burns 0.39gal/hr under no-load conditions according to the study there for a large sedan. Let's assume that the load of putting the blower and heater on equate to even 1 gal/hr (an absurdly high value, the rule of thumb I can find quoted in a few places tends to be add 10-20% depending on interior size and conditions outside). Let's also assume a fuel tank size on the lower end (~15gal) for this sedan. This means in the absolute worst case conditions (you're blasting maximum heat the entire time) around 15 hours of operation for a full tank, 7.5 if you had half a tank. Comparatively, the Tesla, depending on Model, could use as much as 4.8kWh[0][1] under similar worst-case conditions. Modern versions of Tesla and other electrics have or are moving to heat pump heaters, which is encouraging as it will likely be better generally (though this comes with the caveat that they don't work as well in lower temperatures and I believe are supplemented by coil heaters under those conditions). At any rate, the worst-case electric scenario gives a full-charge length of 18.75 (90kWh useable out of a 95kWh pack in the largest long-range models) or 9.38 at half. Note, this is giving the Tesla an enormous advantage here as I'm going with the largest battery pack possible. With the long range pack available in the Model 3 those numbers drop to basically the same as the smaller-tanked gasoline sedans. If you have better sources for those numbers on the Tesla idling with the heaters on, these were all I could find quickly. [0]: https://insideevs.com/news/340327/lets-look-at-energy-consumption-of-tesla-model-3-heater/ https://insideevs.com/news/340327/lets-look-at-energy-consum... [1]: https://teslamotorsclub.com/tmc/threads/idling.139235/ https://teslamotorsclub.com/tmc/threads/idling.139235/

How do electric vechicles hold up in something like this?

by arberx 5y ago

How do electric vechicles hold up in something like this?

grayfaced 5y ago

Not well, the heater is a major drain. If you stop the heater, the batteries get cold and perform significantly worse.

s5300 5y ago
I’m pulling this out of really old knowledge I’ve not looked over in years so may be incorrect… While you are right about “not well”, the other option can often be “not at all” The batteries used in most EV’s should always work to some degree, with regards to temperatures experienced on Earth - the batteries & other systems in most ICE can be completely crippled/not work at all under certain temps faced on Earth Now, you can specifically go out of your way to ruggedize all systems in your ICE so it works to a much better degree than the EV, but the average person is definitely not doing that.
- kube-system 5y ago
  The saving grace with ICE is that they are so inefficient that they literally are mostly heat generators that also produce some mechanical force as a significant byproduct. They might not like starting in the cold, but once they're started, they're fine.
  - beerandt 5y ago
    There's similar efficiency losses for EVs, but (besides battery efficiency or thermal penalties) they're just further upstream.
crooked-v 5y ago
A heat pump system (such as in a Tesla Model Y or a Kia Niro) is significantly more efficient than a plain electric heater, though I haven't seen any hard numbers for cars with that equipment in winter weather.
- dont__panic 5y ago
  Doesn't Tesla recommend that users use the heat as little as possible, and use the seat warmers instead, to conserve battery? Or has that changed in more recent models?

toomuchtodo 5y ago

If they’re not moving and have a heat pump, well, but like a combustion vehicle will exhaust their energy storage eventually. Resistive heat or suboptimal battery architecture? Poorly. Jerrycans for some, tows to Fast DC chargers for others. Class 8 semis should have sufficient diesel reserves for long loiters, even with truckers using auxiliary power units for heat. If not, it is trivial to refuel them on the road with a transfer pump.

whoopdedo 5y ago
Aren't EVs programmed to hold a reserve charge for emergencies? To avoid the cost and inconvenience of a tow, shut off power before you lose the ability to drive yourself to the nearest charger. (Bonus points for adjusting the threshold based on the distance to known stations.) But in the case that a car does drain the battery, how difficult is it to get a portable charger to someone? Have roadside mechanics started carrying generators in their trucks now? They probably should, with the appropriate cables.
- toomuchtodo 5y ago
  To your first paragraph, yes, but battery charge can decline rapidly in the cold at low states of charge. You may exhaust the reserve depending on your circumstances. To your second paragraph, AAA (the tow service) piloted mobile generators for stranded EVs. There was no demand, and the service was discontinued.
- fomine3 5y ago
  Unable to driving is better than freezing death by not using heater.
trompetenaccoun 5y ago
This is a misconception. Heat pumps can improve things a little but often far from as much as people expect. The problem is that in cold conditions most of the loss is from reduced battery performance right from the start. In really cold conditions it can be 50% and more reduction in battery performance. This is energy you're not getting back, heat pump or not. In addition the performance depends on the temperature. There is a sweet spot and the colder it gets from there the less effective it becomes. At around -20 degrees C and below it's effectively useless. There are already vehicles that have been tested in real world conditions. Tesla Model 3s exist with and without heat pump. The difference isn't that large, around 10% more range with the pump in perfect conditions. I've seen people doing tests sleeping in their cars all night and in cold North American winters it's not pretty. With a fully charged battery you will get enough heat for a comfy good nights sleep, 8 hours or so. So lets say in an emergency situation you can stretch it to 12 or so by reducing the temperature. But that's on a full charge! Most cars getting stuck in traffic are not going to have fully charged batteries. It absolutely is a problem with EVs even more than with ICE cars.

exhilaration 5y ago

A stranded ICE vehicle will exhaust its gas tank in 8 hours, max. You can turn it on an off to stretch it out but I wonder if you'll just burn more gas that way. Google (and Quora) suggests that a Tesla will last 36-72 hours, "or less" if it's very cold. I think EVs win in this case, assuming a full tank versus a full charge. Regardless if you're in a place where this could happen you should have a box of chemical handwarmers, a heavy blanket, food, water, and other stuff in a box for emergencies. Edit: looks like I'm wrong, much better answers below!

relaytheurgency 5y ago
Where are you getting the 8 hours from? A car that gets 30 mpg with a 14 gallon tank can _drive_ for nearly 8 hours at 60 mph. That same car may burn (on the highest end) 1/2 a gallon an hour idling which would be more than 24 hours of idling time.
hotpotamus 5y ago
8 hours seems quite quick. I've heard that the average car will idle for 2 days on a full tank, though I haven't tried it myself.
BeefWellington 5y ago
> A stranded ICE vehicle will exhaust its gas tank in 8 hours, max. You can turn it on an off to stretch it out but I wonder if you'll just burn more gas that way. Idling consumes little gas compared with actually moving the vehicle: https://www.energy.gov/eere/vehicles/fact-861-february-23-2015-idle-fuel-consumption-selected-gasoline-and-diesel-vehicles https://www.energy.gov/eere/vehicles/fact-861-february-23-20... A 4.2L engine burns 0.39gal/hr under no-load conditions according to the study there for a large sedan. Let's assume that the load of putting the blower and heater on equate to even 1 gal/hr (an absurdly high value, the rule of thumb I can find quoted in a few places tends to be add 10-20% depending on interior size and conditions outside). Let's also assume a fuel tank size on the lower end (~15gal) for this sedan. This means in the absolute worst case conditions (you're blasting maximum heat the entire time) around 15 hours of operation for a full tank, 7.5 if you had half a tank. Comparatively, the Tesla, depending on Model, could use as much as 4.8kWh[0][1] under similar worst-case conditions. Modern versions of Tesla and other electrics have or are moving to heat pump heaters, which is encouraging as it will likely be better generally (though this comes with the caveat that they don't work as well in lower temperatures and I believe are supplemented by coil heaters under those conditions). At any rate, the worst-case electric scenario gives a full-charge length of 18.75 (90kWh useable out of a 95kWh pack in the largest long-range models) or 9.38 at half. Note, this is giving the Tesla an enormous advantage here as I'm going with the largest battery pack possible. With the long range pack available in the Model 3 those numbers drop to basically the same as the smaller-tanked gasoline sedans. If you have better sources for those numbers on the Tesla idling with the heaters on, these were all I could find quickly. [0]: https://insideevs.com/news/340327/lets-look-at-energy-consumption-of-tesla-model-3-heater/ https://insideevs.com/news/340327/lets-look-at-energy-consum... [1]: https://teslamotorsclub.com/tmc/threads/idling.139235/ https://teslamotorsclub.com/tmc/threads/idling.139235/