Range loss in cold weather

[Tonyk2034]

I was wondering if there was any ongoing research or developments or improvements

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[Saskateam]

All electric cars lose range with temperature but so do ICE cars. It is only temporary and will be better again when warm. Battery size and charge speed is the best way to overcome this issue. The bigger the battery the more capacity it has to run the thermal management and warm the batteries which lets you go further in the cold. Faster charging let’s you get back on the road faster and not cool down to much. Right now you will loose 1/4 to 1/3 range around -20C. The colder batteries are only one aspect of this reduced range. The denser air has a lot to do with it. My current ICE vehicle goes between 500-600km on a tank depending on wind in the summer. In the winter I get between 400-450km per tank. So an ICE vehicle loses 1/4-1/3 range in winter too. Drag coefficient and efficiency of electric are better than ICE cars so that helps. You can change your heating in an EV and get more range. I have a heated hoodie that I will use to help me get more range by reducing the heat output if I need. Can’t do that in an ICE vehicle.

 

[mggoulet]

All electric cars lose range with temperature but so do ICE cars. It is only temporary and will be better again when warm. Battery size and charge speed is the best way to overcome this issue. The bigger the battery the more capacity it has to run the thermal management and warm the batteries which lets you go further in the cold. Faster charging let’s you get back on the road faster and not cool down to much. Right now you will loose 1/4 to 1/3 range around -20C. The colder batteries are only one aspect of this reduced range. The denser air has a lot to do with it. My current ICE vehicle goes between 500-600km on a tank depending on wind in the summer. In the winter I get between 400-450km per tank. So an ICE vehicle loses 1/4-1/3 range in winter too. Drag coefficient and efficiency of electric are better than ICE cars so that helps. You can change your heating in an EV and get more range. I have a heated hoodie that I will use to help me get more range by reducing the heat output if I need. Can’t do that in an ICE vehicle.

As recommended, we heat our garage at 10C... That means the lose range during winter time should not really affect CT tri-motor... Do you know what will be the currency change value from USD to CAD ...according to tesla 3 it is around 1.5 more but the full self driving is $7,000 USD to $9,200 CAD... the tri-motor at $70,000 USD should be at $92,000 CAD ...???

 

[Tonyk2034]

I can only hope but I believe the tri motor will be over a 100,000 plus taxes, l believe Elon is just giving canadians a more reasonable price on the software not the truck. Maybe when a new bank of Canada governor gets appointed he or she won’t be so aligned with the exporters and let the Canadian peso rebound to some degree.

 

[Tonyk2034]

I meant to say including taxes

 

[mggoulet]

I meant to say including taxes

If you have enough pennies USD you can probably buy it from US and within 3 weeks to bring it to Canada and paying taxes to the province and not to US... the procedure is a bit complex... we followed a kind of course in Montréal to proceed ... so, that's why we ordered one for our home in Fl. And 2 other for Montréal if the subsidies still exist ...??? So, if the exchange is to high... it can be reduce by the government of Québec =$8,000 and Canada=$5,000 for total of $13,000 CAD. Finally, I wish to have news as soon as possible to decide what to do... the second CT is for my other son living in Ontario where Ford abolish the subsidies for EV...for me it is a curious mentallity that we do not agree...!!!

 

[Tonyk2034]

I have enough usd but not as much as you I am only buying one truck. Must say congratulations for buying one for your son. I have two son’s living in Toronto they are still fairly young. I would like to purchase them a home never mind a truck each. No the exchange doesn’t bother me. I am used to spending more on items it comes with where we live.I suspect you must have been an exporter to acknowledge my comment and call it pennies. My kids don’t have any debt both well educated, Would like to help them more right now. What I was trying to find out if there was anything new happening in respect to cold weather range loss. There possibly is but more than likely too expensive to install at this time. If you have any information on this topic I wouldn’t mind reading same. Thanks for your reply though.

 

[Saskateam]

As recommended, we heat our garage at 10C... That means the lose range during winter time should not really affect CT tri-motor... Do you know what will be the currency change value from USD to CAD ...according to tesla 3 it is around 1.5 more but the full self driving is $7,000 USD to $9,200 CAD... the tri-motor at $70,000 USD should be at $92,000 CAD ...???

It is not a straight conversation for buying in Canada to the US market. Tesla needs to set a price that it thinks they can sell their vehicle in that market. It is close to the exchange rate however incentives, taxes, and infrastructure will also play a role in the final price for the Canadian market. This does not mean we will get a deal. I see a lot of things sold here in Canada that are more expensive than just the increase from the exchange rate for the US price. We rarely get a good deal on the price in Canada.

 

[Tonyk2034]

I agree with you the price will be close to what you’re indicating. Tesla is a publicly traded company therefore there will be more pressures to meet shareholders expectations and it appears to me the rational for dealing with Canadian buyers that we are known to purchase items at higher prices and we don’t complain for the most part. So the price could be a thousand to fifteen hundred hire because of the weakness in our dollar. 2020 could be a very difficult year economically.

 

[ajdelange]

I was wondering if there was any ongoing research...

Certainly. Range anxiety may have moved down the list of concerns a bit but it is still a concern, especially among prospective buyers (once you drive a BEV you quickly come to realize that you shouldn't have been worrying about range in the first place). And more range is always nice to have in any case. Someone on one of these forums said recently that it's like extra runway. Reduced energy use can be harvested as more range or as less battery cost so there is lots of ongoing research on how to make the cars more efficient and/or the batteries at less cost per kWh. With respect to cod weather performance the goal is to harvest all the waste heat, to minimize air leakage and to be sure regen recovery is available from the moment you leave the garage in the morning.

... or developments or improvements

Tesla filed a patent last summer for a whole vehicle heating/cooling system in which, from a cursory glance, it appears that the motors, inverters, rectifiers, cabin and outside heat exchangers, compressors, and battery can all be switched into or out of loops that take any heat from where it is not needed and shunt it to where it is needed or overboard. That should improve the picture with respect to cold battery somewhat i.e. it should warm faster once one starts driving with the goal being to get it to the point where regen never has to be restricted. Tesla now has an option to set charging to finish at a specified time. When the battery charges (or discharges) heat is dissipated in it internally so that it will be warmest at the completion of charging. Charging also produces waste heat at the recitifier/boost converter. If this heat is recaptured it can be shunted back to the battery.

The cabin can be remotely brought to temperature before departure so there will not be a big demand for cabin heat as you pull out of the garage. What is missing is the ability to use the battery heater to bring the pack to sufficient temperature for full regen. I am not certain of this but am pretty sure that one of last summers downloads raised the threshold at which regen restriction starts. This should be, IMO, offset with a 'bring battery to regen temp on shore power' option. As the cars have sources of heat which can be used for this purpose (the S and X have separate battery heaters) this should be an easy thing to do.

There are some things that the engineers can't fix such as the fact that air density at -20 °C is 16% greater than it is at +20 °C. As drag is proportional to air density that means more power lost to drag but as drag is a relatively small power sink that won't make a huge difference but a noticeable one nevertheless. They also can't prevent the extra stuff on the road surface (rain, snow, sand, salt) that seems to be there more in winter than summer and which gobbles quite a bit of power.

You will see lots of reports that cold weather will cost you half your range. I'm sure it's possible to lose that much but if you pre-warm the cabin and pre-warm the battery (by charging) and clear snow and ice off (rough surface contributes to drag) and use the seat heater rather than the cabin heater you will experience much less loss. My winter temperatures seldom go below 0 °C. I use 294 Wh/mi in the summer and 301 in the winter but there are other factors besides temperature at play as summers are spent in Quebec and winters in Virginia.

 

[Michael Mehta]

My 2017 Chevrolet Volt has approximately 15 kWh of battery storage. In the summer, this can get me up to 100 km of range. Most of the year the range is closer to 80 km. During the worst of winter (where it sometimes get below -30C), it drops to about 60 km of range. In other words, a decrease of 25%. I have seen the same thing with gas and diesel cars in the past.

 

[ajdelange]

"Stats" is a smart phone app that polls your Tesla and tells you things about charges, energy use etc. It collects data on 'efficiency' which is the ratio of EPA rated utilization to the vehicle's utilization. It has a historical display over time of fleet efficiency which, obviously, varies seasonally, It collects this data from the fleet. Efficiency is pretty flat over the warmer months at 96% meaning that the average driver gets 96% of the EPA rated range. In the cooler months that declines to a fairly constant fleet average of 84%. At the moment fleet efficiency is up a bit at 85% with the worst driven getting 45% and the best (who is, not that I like bragging, moi) getting 116%. Thus getting into a car soaked to -20 °C, turning the cabin heater way up, driving with outdoor air selected rather than recirculate, turning on the steering wheel and seat heaters and cracking a window or two while driving fast at night in hilly terrain with the radio blaring on roads covered with snow can cost you over half your range. In a more moderate (but still cold) environment with some attention to consumption you can still achieve or do a little better than the EPA rating.

 

[mggoulet]

"Stats" is a smart phone app that polls your Tesla and tells you things about charges, energy use etc. It collects data on 'efficiency' which is the ratio of EPA rated utilization to the vehicle's utilization. It has a historical display over time of fleet efficiency which, obviously, varies seasonally, It collects this data from the fleet. Efficiency is pretty flat over the warmer months at 96% meaning that the average driver gets 96% of the EPA rated range. In the cooler months that declines to a fairly constant fleet average of 84%. At the moment fleet efficiency is up a bit at 85% with the worst driven getting 45% and the best (who is, not that I like bragging, moi) getting 116%. Thus getting into a car soaked to -20 °C, turning the cabin heater way up, driving with outdoor air selected rather than recirculate, turning on the steering wheel and seat heaters and cracking a window or two while driving fast at night in hilly terrain with the radio blaring on roads covered with snow can cost you over half your range. In a more moderate (but still cold) environment with some attention to consumption you can still achieve or do a little better than the EPA rating.

When we drive to Fl. on 81 or 95, the average speed on right lane is 120kmh=72mph. With tesla 3 of my son, we see a big difference in range if we drive at 100 kmh vs 118kmh which is the limit before the police might ask you questions !!! Did you figure out the impact on the range ???

 

[ajdelange]

I can easily figure that driving at 118 kmph means that you will be using 39.24% more energy to push the air out of the way than you would at 100 kmph but what I don't know is what part of the total load on the motors/battery this corresponds to. The drag load is only one of several loads and it is not the largest and how much influence it has on range will depend on how big the other loads are relative to it.

Last time I drove from Lebanon to Ogden (on 95) average speed was 62 mph and I used 333 Wh/mi. Last time I drove from Ogden to Brattleboro (on 95) it cost me 366 Wh/mi even though I was going a little slower at 60 mph average. Thus slower speed gave less range in this particular case. In going from Lebanon to Ogden I went up 410 feet in elevation and in going from Ogden to Brattleboro I went down 305 feet. Utilization southbound should be less than northbound from this factor too so something else was clearly dominant with respect to the drag and gravitational loads. In this case it was rolling resistance. The road surface was wet for the southbound trip and that cost me about 20% utilization (20% reduction in range). I had observed similar losses in range on 95 due to wet road surface before.

To summarize: there are several loads
1)Drive train losses
2)Wheel slip losses
3)Drag losses
4)Rolling resistance losses
5)Gravitational losses
6)Inertial losses

It's easy to calculate change in drag losses from speed alone (but it is airspeed, not groundspeed so you must know about winds) and increasing speed will always increase drag and always decrease range but whether the range reduction from a given speed increase is significant or not depends on the other 5 loads too. So no, I cannot calculate the range reduction from the speed any more than I can calculate the range loss from cold even though I know drag increases by 16% if the air temperature drops from +20 to -20 °C.

The best thing to do is monitor the energy display as you go. For those readers who do not presently own Teslas this is a graph that shows battery percent charge on the vertical axis and miles on the horizontal. To the left of the distance you have driven the % is historical. To the right it is predicted based on your use in the last few miles and the terrain ahead. The remaining % at destination is prominently displayed and your job is to be sure that it is a number comfortably above 0. If it gets very low your first move is to slow down. Drag does count, But reducing speed may not save the day in which case you have to find a charger. Also note that there are Super Chargers just off 95 at Lebanon and Brattleboro.

 

[mggoulet]

I can easily figure that driving at 118 kmph means that you will be using 39.24% more energy to push the air out of the way than you would at 100 kmph but what I don't know is what part of the total load on the motors/battery this corresponds to. The drag load is only one of several loads and it is not the largest and how much influence it has on range will depend on how big the other loads are relative to it.

Last time I drove from Lebanon to Ogden (on 95) average speed was 62 mph and I used 333 Wh/mi. Last time I drove from Ogden to Brattleboro (on 95) it cost me 366 Wh/mi even though I was going a little slower at 60 mph average. Thus slower speed gave less range in this particular case. In going from Lebanon to Ogden I went up 410 feet in elevation and in going from Ogden to Brattleboro I went down 305 feet. Utilization southbound should be less than northbound from this factor too so something else was clearly dominant with respect to the drag and gravitational loads. In this case it was rolling resistance. The road surface was wet for the southbound trip and that cost me about 20% utilization (20% reduction in range). I had observed similar losses in range on 95 due to wet road surface before.

To summarize: there are several loads
1)Drive train losses
2)Wheel slip losses
3)Drag losses
4)Rolling resistance losses
5)Gravitational losses
6)Inertial losses

It's easy to calculate change in drag losses from speed alone (but it is airspeed, not groundspeed so you must know about winds) and increasing speed will always increase drag and always decrease range but whether the range reduction from a given speed increase is significant or not depends on the other 5 loads too. So no, I cannot calculate the range reduction from the speed any more than I can calculate the range loss from cold even though I know drag increases by 16% if the air temperature drops from +20 to -20 °C.

The best thing to do is monitor the energy display as you go. For those readers who do not presently own Teslas this is a graph that shows battery percent charge on the vertical axis and miles on the horizontal. To the left of the distance you have driven the % is historical. To the right it is predicted based on your use in the last few miles and the terrain ahead. The remaining % at destination is prominently displayed and your job is to be sure that it is a number comfortably above 0. If it gets very low your first move is to slow down. Drag does count, But reducing speed may not save the day in which case you have to find a charger. Also note that there are Super Chargers just off 95 at Lebanon and Brattleboro.

I can easily figure that driving at 118 kmph means that you will be using 39.24% more energy to push the air out of the way than you would at 100 kmph but what I don't know is what part of the total load on the motors/battery this corresponds to. The drag load is only one of several loads and it is not the largest and how much influence it has on range will depend on how big the other loads are relative to it.

Last time I drove from Lebanon to Ogden (on 95) average speed was 62 mph and I used 333 Wh/mi. Last time I drove from Ogden to Brattleboro (on 95) it cost me 366 Wh/mi even though I was going a little slower at 60 mph average. Thus slower speed gave less range in this particular case. In going from Lebanon to Ogden I went up 410 feet in elevation and in going from Ogden to Brattleboro I went down 305 feet. Utilization southbound should be less than northbound from this factor too so something else was clearly dominant with respect to the drag and gravitational loads. In this case it was rolling resistance. The road surface was wet for the southbound trip and that cost me about 20% utilization (20% reduction in range). I had observed similar losses in range on 95 due to wet road surface before.

To summarize: there are several loads
1)Drive train losses
2)Wheel slip losses
3)Drag losses
4)Rolling resistance losses
5)Gravitational losses
6)Inertial losses

It's easy to calculate change in drag losses from speed alone (but it is airspeed, not groundspeed so you must know about winds) and increasing speed will always increase drag and always decrease range but whether the range reduction from a given speed increase is significant or not depends on the other 5 loads too. So no, I cannot calculate the range reduction from the speed any more than I can calculate the range loss from cold even though I know drag increases by 16% if the air temperature drops from +20 to -20 °C.

The best thing to do is monitor the energy display as you go. For those readers who do not presently own Teslas this is a graph that shows battery percent charge on the vertical axis and miles on the horizontal. To the left of the distance you have driven the % is historical. To the right it is predicted based on your use in the last few miles and the terrain ahead. The remaining % at destination is prominently displayed and your job is to be sure that it is a number comfortably above 0. If it gets very low your first move is to slow down. Drag does count, But reducing speed may not save the day in which case you have to find a charger. Also note that there are Super Chargers just off 95 at Lebanon and Brattleboro.

Merci pour ces belles précisions... I know that my son with model 3 has increase his range because of reducing his speed... (as his is md, specialist) sometimes he has to speed up...!!! But as we are retired (66) we will follow the distance of about 300 km from one supercharger to another one (we expected to get 300 km within 20 minutes...???). As I was in econometrics method for the largest financial institution in Québec, I would be happy to collect data and see my forecast... but M. Elon Musk should give that with the computer inside the car...