How Much Does the LEAF Lose In The Cold?

[RegGuheert]

What a beautiful sunny day we had here today! Temps in the low 70's, and hardly a breeze. My LEAF and I traveled 33 miles, about a third of it freeway, and got 4.5 m/kWh. I know, that's not particularly remarkable, except that:

• I'm not what you would call a timid driver, having averaged only 4.0 m/kWh over the life of the car.
• Unlike the apparent majority of LEAF drivers, I usually get my worst mileage driving in town.
• For the past three months my daily averages have been between 2.9 and 3.6 m/kWh.

During the Summer I average 5.8 to 6.2 miles/K. Winter about 4-4.3. The other day I posted pix on FB that I was at 5.3 miles per K.

Ray and Dave, I see the same trend on my dash, but I question the accuracy of those numbers. If I drive to a destination using extreme hypermiling techniques and arrive with more battery than I have ever arrived with, am I supposed to believ the dashboard when it tells me that trip was LESS efficient than all of the others. Sorry, but it doesn't add up.

 

[DaveinOlyWA]

What a beautiful sunny day we had here today! Temps in the low 70's, and hardly a breeze. My LEAF and I traveled 33 miles, about a third of it freeway, and got 4.5 m/kWh. I know, that's not particularly remarkable, except that:

• I'm not what you would call a timid driver, having averaged only 4.0 m/kWh over the life of the car.
• Unlike the apparent majority of LEAF drivers, I usually get my worst mileage driving in town.
• For the past three months my daily averages have been between 2.9 and 3.6 m/kWh.

During the Summer I average 5.8 to 6.2 miles/K. Winter about 4-4.3. The other day I posted pix on FB that I was at 5.3 miles per K.

Ray and Dave, I see the same trend on my dash, but I question the accuracy of those numbers. If I drive to a destination using extreme hypermiling techniques and arrive with more battery than I have ever arrived with, am I supposed to believ the dashboard when it tells me that trip was LESS efficient than all of the others. Sorry, but it doesn't add up.

no comment on the accuracy of the numbers from me EVER. they are used for relational purposes only and that is all they have ever meant to me.

what i track is my cost. IOW, juice from wall i pay for. the rest is tracked but only because its better to have the info than not. (i found out too late that there were many things i should have tracked and didnt to my regret, small as it may be)

there are a lot of things about the LEAF that are questions in my mind especially ones concerning the readouts and gauges and maybe it all started with the obvious "variations" of the carwings #'s or not, I dont know but I look at all the numbers with the exception of the federally mandated odometer with a VERY skeptical eye

 

[TonyWilliams]

I look at all the numbers with the exception of the federally mandated odometer with a VERY skeptical eye

I have bed news for you:

Federal Odometer Act - passed in 1972.... contains no provisions for odometer accuracy

 

[surfingslovak]

I looked at the FleetCarma chart, Pamela Thwaite's data and Ricardo Borba's blog post from last year. It's an anecdotal and widely diverging data collection, but the aggregate loss of range seems to be between 0.5 to 0.6% per degree Fahrenheit below room temperature. I thought that was interesting. This figure apparently includes (resistive) heater use as well.

 

[RegGuheert]

I looked at the FleetCarma chart, Pamela Thwaite's data and Ricardo Borba's blog post from last year. It's an anecdotal and widely diverging data collection, but the aggregate loss of range seems to be between 0.5 to 0.6% per degree Fahrenheit below room temperature. I thought that was interesting. This figure apparently includes (resistive) heater use as well.

Thanks for the data! It seems the first plot in your post is for the Nissan LEAF while the second plot is for the ActiveE. Is that correct?

If so, it brings up an interesting point: Range degrades with temperature in an EV with a battery TMS system just like without one. Of course the heater is part of this, but the point goes much farther than that: It seems that there may be a crossover related to the TIME that passes between the beginning of the drive and when it completes and which approach gives better range. For instance, I can believe that active battery TMS gives better cold-temperature range if you warm the cabin, unplug, drive your miles and then plug back in. But in the scenario where you warm the cabin, unplug, drive to a destination, park for some long period of time (nine hours at work or perhaps overnight or longer) and then drive back and plug in, then the EV without a battery TMS may have the better range in the cold. In other words, the blanket statement that I have read so many times that battery TMS gives betters cold-weather range is really only true for specific driving conditions.

I will also note that the longest trip in the plot for the ActiveE occurred between 50F and 60F. This matches Nissan projection for 2013 peak range occurring at right around 60F when the climate control is in use. I've been thinking about it for a while and it seems to make sense if you assume that most trips are taken during the daytime when solar loading would tend to make that approximately the temperature at which the least climate control is needed for optimum cabin temperature.

 

[DaveinOlyWA]

I looked at the FleetCarma chart, Pamela Thwaite's data and Ricardo Borba's blog post from last year. It's an anecdotal and widely diverging data collection, but the aggregate loss of range seems to be between 0.5 to 0.6% per degree Fahrenheit below room temperature. I thought that was interesting. This figure apparently includes (resistive) heater use as well.

Thanks for the data! It seems the first plot in your post is for the Nissan LEAF while the second plot is for the ActiveE. Is that correct?

If so, it brings up an interesting point: Range degrades with temperature in an EV with a battery TMS system just like without one. Of course the heater is part of this, but the point goes much farther than that: It seems that there may be a crossover related to the TIME that passes between the beginning of the drive and when it completes and which approach gives better range. For instance, I can believe that active battery TMS gives better cold-temperature range if you warm the cabin, unplug, drive your miles and then plug back in. But in the scenario where you warm the cabin, unplug, drive to a destination, park for some long period of time (nine hours at work or perhaps overnight or longer) and then drive back and plug in, then the EV without a battery TMS may have the better range in the cold. In other words, the blanket statement that I have read so many times that battery TMS gives betters cold-weather range is really only true for specific driving conditions.

I will also note that the longest trip in the plot for the ActiveE occurred between 50F and 60F. This matches Nissan projection for 2013 peak range occurring at right around 60F when the climate control is in use. I've been thinking about it for a while and it seems to make sense if you assume that most trips are taken during the daytime when solar loading would tend to make that approximately the temperature at which the least climate control is needed for optimum cabin temperature.

so does "TMS" mean temperature management system or "time mismanagement system?"


**note** the above comment was only a joke so dont take it seriously

 

[edatoakrun]

...Range degrades with temperature in an EV with a battery TMS system just like without one. Of course the heater is part of this, but the point goes much farther than that....

My personal observation, based on very imprecise observations, is that my LEAF only loses ~5% of it's battery capacity when recharged at ~40F rather than ~80F, the highest and lowest temperatures I've range-tested without using the heater or AC.

So, I believe that while range will be reduced by several times that ~5% due to the same 40 F reduction in battery and ambient temperature, as well as heater use, the potential benefit from ATM will always be limited to the order of that ~5% maximum, less it's own Wh consumption, as you have noted.

The charts don't show much data for below freezing, and I haven't much experience there either, but I would expect much greater benefits from ATM in those colder conditions, especially when most of the heat energy is coming from the grid, rather than from the battery.

 

[Berlino]

I've not experienced winter in my LEAF yet, but I'm dumbfounded as to how they arrive at such low figures for the LEAF's summer range. I've asked if they'll share some more information on the LEAFs used to compile the statistics, because the driver profiles may be skewing the statistics. Also, the word "daily" before "range capacity" should probably be replaced by "Full Charge," since many people can recharge during the day.

A local car-sharing service, Communauto has a fleet of 24 LEAFs which may be tracked by fleetcarma.

Communauto's clients likely get much less range than the average LEAF owner:

1) They don't have access to Carwings in order to pre-heat or pre-cool the cabin.
2) They rent by the hour for short trips and thus have almost no range-anxiety, so they drive aggressively and run the A/C or heat full-blast.*
3) The few Communauto parking locations I'm aware of were in lots which were not heated or insulated.

Similarly, many of the other fleetcarma-racked LEAFs may be driven by employees or other non-owners that wouldn't be concerned about practicing the slightest range-friendly driving habits.


* Since fleetcarma published that graph, Communauto has changed the way it rents LEAFs in a way that drivers are no longer assured of picking up a fully-charged EV, so driver's habits may change.

 

[TonyAndTina]

Very helpful info. The outside temp is dropping and the best we could manage is about 4.5m/kwh thus far. Look forward to warmer weather!

 

[GetOffYourGas]

Now that the temperatures are dropping again, I'm lucky to average 3 miles/kWh these days. My wife drives the car during the day, and she typically gets 2.5. But most of her trips are less than 20 miles round trip, so approximately zero effort is put into efficiency. Comfort is king. With two kids in the back seat, we run the heater (often cannot preheat), jump on the highway (72 mph is keeping up with traffic), and drive 5-10 miles, with the horribly inefficient heater pulling 5-6kW. Then the car soaks for a while, and the process is repeated.

With about 10% degradation, the car has about 18kWh of useable energy. That's good for 2.5*18 = 45 miles. Trying marginally harder (slowing down, car on ECO), we can get 3*18 = 54 miles.

 

[DaveinOlyWA]

Now that the temperatures are dropping again, I'm lucky to average 3 miles/kWh these days. My wife drives the car during the day, and she typically gets 2.5. But most of her trips are less than 20 miles round trip, so approximately zero effort is put into efficiency. Comfort is king. With two kids in the back seat, we run the heater (often cannot preheat), jump on the highway (72 mph is keeping up with traffic), and drive 5-10 miles, with the horribly inefficient heater pulling 5-6kW. Then the car soaks for a while, and the process is repeated.

With about 10% degradation, the car has about 18kWh of useable energy. That's good for 2.5*18 = 45 miles. Trying marginally harder (slowing down, car on ECO), we can get 3*18 = 54 miles.

check your tire pressures. rule of thumb says you lose about 1 PSI per 10ºF drop in temps. I added about 4 PSI to mine.

 

[GetOffYourGas]

Now that the temperatures are dropping again, I'm lucky to average 3 miles/kWh these days. My wife drives the car during the day, and she typically gets 2.5. But most of her trips are less than 20 miles round trip, so approximately zero effort is put into efficiency. Comfort is king. With two kids in the back seat, we run the heater (often cannot preheat), jump on the highway (72 mph is keeping up with traffic), and drive 5-10 miles, with the horribly inefficient heater pulling 5-6kW. Then the car soaks for a while, and the process is repeated.

With about 10% degradation, the car has about 18kWh of useable energy. That's good for 2.5*18 = 45 miles. Trying marginally harder (slowing down, car on ECO), we can get 3*18 = 54 miles.

check your tire pressures. rule of thumb says you lose about 1 PSI per 10ºF drop in temps. I added about 4 PSI to mine.

I just measured 37-38psi all around. Currently 39F. Doesn't seem like that would make a significant difference.

 

[DaveinOlyWA]

Now that the temperatures are dropping again, I'm lucky to average 3 miles/kWh these days. My wife drives the car during the day, and she typically gets 2.5. But most of her trips are less than 20 miles round trip, so approximately zero effort is put into efficiency. Comfort is king. With two kids in the back seat, we run the heater (often cannot preheat), jump on the highway (72 mph is keeping up with traffic), and drive 5-10 miles, with the horribly inefficient heater pulling 5-6kW. Then the car soaks for a while, and the process is repeated.

With about 10% degradation, the car has about 18kWh of useable energy. That's good for 2.5*18 = 45 miles. Trying marginally harder (slowing down, car on ECO), we can get 3*18 = 54 miles.

check your tire pressures. rule of thumb says you lose about 1 PSI per 10ºF drop in temps. I added about 4 PSI to mine.

I just measured 37-38psi all around. Currently 39F. Doesn't seem like that would make a significant difference.

hmm, you're in Syracuse? Temps in the teens I have to think happens in your area at least a dozen or more times a winter? that takes that 37 PSI into 34-35 PSI.

that is a huge difference. Keep in mind, you have already lost a lot of range simply because its Winter. do you really want to lose 5 more miles over something as easy to fix as tire pressure?

 

[GetOffYourGas]

check your tire pressures. rule of thumb says you lose about 1 PSI per 10ºF drop in temps. I added about 4 PSI to mine.

I just measured 37-38psi all around. Currently 39F. Doesn't seem like that would make a significant difference.

hmm, you're in Syracuse? Temps in the teens I have to think happens in your area at least a dozen or more times a winter? that takes that 37 PSI into 34-35 PSI.

that is a huge difference. Keep in mind, you have already lost a lot of range simply because its Winter. do you really want to lose 5 more miles over something as easy to fix as tire pressure?

Sure, temperatures dip below zero a couple of times each winter, mostly at night. Highs in the teens are not uncommon for a few weeks of the year.

My question to you is - how much range is really lost going from 40psi to 35psi?

The biggest hit to me is that heater - often times I can't get around using it.

The next biggest hit is the air density. This is easier to mitigate by driving slower. I usually keep up with traffic - I don't want EVs to look like they can't - which means driving ~72mph. The posted speed limit is 65mph. The difference in efficiency is noticeable, and even larger in the winter, due to the denser air.

 

[LeftieBiker]

My question to you is - how much range is really lost going from 40psi to 35psi?

There is another issue: the Ecopias seem to be a lot more fragile at pressures in the mid thirties than they are up around 40psi. Do you really want to have a blowout if you hit a curb in cold weather?

 

[GetOffYourGas]

My question to you is - how much range is really lost going from 40psi to 35psi?

There is another issue: the Ecopias seem to be a lot more fragile at pressures in the mid thirties than they are up around 40psi. Do you really want to have a blowout if you hit a curb in cold weather?

Interesting fact I was not aware of. This is made worse by the lack of a true spare tire.

In reality, I should be putting winter tires on the car. But then what does that do to the rolling resistance? It's probably higher than the stock Ecopias.

Keep in mind, you have already lost a lot of range simply because its Winter. do you really want to lose 5 more miles over something as easy to fix as tire pressure?

I never directly answered this, but it was implied in my first post. I don't actually care if I lose 5 more miles. It doesn't matter in the least whether my range is 45 or 50 miles, if I'm only driving 30 miles per day!

 

[LeftieBiker]

In reality, I should be putting winter tires on the car. But then what does that do to the rolling resistance? It's probably higher than the stock Ecopias.

I've only lost a bit less than 2% energy efficiency by putting snows on. But I have them inflated to 40psi - I'm sure it will be more when I lower the pressures to the upper thirties.

 

[DaveinOlyWA]

Sure, temperatures dip below zero a couple of times each winter, mostly at night. Highs in the teens are not uncommon for a few weeks of the year.

My question to you is - how much range is really lost going from 40psi to 35psi?

The biggest hit to me is that heater - often times I can't get around using it.

The next biggest hit is the air density. This is easier to mitigate by driving slower. I usually keep up with traffic - I don't want EVs to look like they can't - which means driving ~72mph. The posted speed limit is 65mph. The difference in efficiency is noticeable, and even larger in the winter, due to the denser air.

i would be more worried about sidewall flex. you will probably lose a few miles in range, like 2-3 if I had to guess so unless you are cutting it real close (I do...last night pulled in with 13 GID which is normal...) you dont have to worry about it.

but lets examine the situation. your tires CAN EASILY be at 50 PSI and be PERFECTLY safe. in Summer your tire pressures are frequently over that anyway due to heat.

In Winter you can either set your PSI at borderline acceptable on the low end (where you have very little leeway) or on the high end (where you have quite a bit of leeway) during a time when cold weather will have a downward effect on your set pressure.

there is NO REASON to follow your manufacturers recommendation other than comfort. that is the basis of their settings. so you can add a few pounds whenever you get that cold snap, or do what I do then take it out when it warms up to normal or set it at the beginning of Winter and not worry if I am at 44½ PSI every once in a while

 

[dgpcolorado]

...In reality, I should be putting winter tires on the car. But then what does that do to the rolling resistance? It's probably higher than the stock Ecopias.

Yes, you will take a hit to mileage efficiency with snow tires.

I never directly answered this, but it was implied in my first post. I don't actually care if I lose 5 more miles. It doesn't matter in the least whether my range is 45 or 50 miles, if I'm only driving 30 miles per day!

In that case, snow tires won't be a problem. If snow tires increase the utility of the LEAF by allowing use of the car in snowy weather, and range isn't an issue, you really ought to use them.