My Leaf Stats : Range vs Temperature

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evnow

Well-known member
Joined
Apr 22, 2010
Messages
11,480
Location
Seattle, WA
This is from all the data I've been logging over the past 8 months.

Range is calculated as 21.5 * Leaf m/kWh. Ofcourse the shape & correlation to temperature won't change if we use a different figure. Temperature comes from http://www.beautifulseattle.com" onclick="window.open(this.href);return false;.

rangevstemp.png


Data behind this.

leaf-stats.png
 
Very interesting; thanks for posting. I suspect I'm seeing the beginning of "range limiting temperature effects", and I'm curious how dramatic it will be in our mild environment (similar to yours).
 
The big question is, is the climate control responsible for most of this? Or is the battery performance alone affected to such an extent by temperature?
 
johnr said:
The big question is, is the climate control responsible for most of this? Or is the battery performance alone affected to such an extent by temperature?

I believe that mostly is the climate control. My wife does 2-3 25 miles round trips a day and she preheats in the morning and if needed on the third trip in the evening. Her average dropped from around 4.7 and above to 4.6 and below (miles/kWh). We did not notice a big drop in the range.

In the weekends, we even tried longer round trips up to 80 miles, as now there are L2 chargers on the way back (if needed). My wife drives and I try keep the climate control from killing the range.
 
johnr said:
The big question is, is the climate control responsible for most of this? Or is the battery performance alone affected to such an extent by temperature?

For me, it is definitely the temp of the battery pack. I don't use the heater, but will use heated seat cushions soon. In the high heat during the summer, I still can get over 6+ without any problem, but I've noticed since our weather has turned cooler and my battery temp has dropped from six to five bars, my m/kW h has decreased to the high 5's. I've lost around .5.
 
I've noticed this, too. I"ve been doing a ~60 mile round trip on weekends since I got my car in August. It's on 35mph to 50mph rural roads; in August I was getting 5.2 to 5.5 mi/kwh, in October, 4.6 to 4.8 mi/kwh. Yesterday, with the car showing 42 degrees, I got 4.5 mi/kwh.

Climate control has been off on these trips.
 
Makes you wonder why the pack heater on the newest Leaf cars doesnt gently warm the pack when its temp falls below say 50

small amount of energy and then better more consistent range

instead it does not activate til pack temps reach a range killing -4 F

why ?
 
Very interesting data! Does anyone have similar data going down below freezing? I gets pretty cold here in Chicago!
 
kmp647 said:
Makes you wonder why the pack heater on the newest Leaf cars doesnt gently warm the pack when its temp falls below say 50

small amount of energy and then better more consistent range

instead it does not activate til pack temps reach a range killing -4 F

why ?

Could be a couple of reasons:
1) We don't know HOW LONG the "heater" stays on even when it does kick in
2) There's substantial "self heating" in batteries when used

I'm sure Nissan did a lot of simulation/testing around temperature; we just don't know what the critical points are (other than -4 F).
 
There is nothing stopping the owner from adding an external battery heater, they are available all over the internet.
 
UhClem said:
I've noticed this, too. I"ve been doing a ~60 mile round trip on weekends since I got my car in August. It's on 35mph to 50mph rural roads; in August I was getting 5.2 to 5.5 mi/kwh, in October, 4.6 to 4.8 mi/kwh. Yesterday, with the car showing 42 degrees, I got 4.5 mi/kwh.

Climate control has been off on these trips.

I fail to understand how the temperature will affect the mi/kWh unless you have additional electrical load at lower temperatures (climate control, lights, windshield wiper, water on the road, more wind ... edit: tire pressure). I understand that at lower temperature the capacity of the battery will decrease and affect the range, but the mi/kWh should not change.

Does the car software keeps track of the energy put in the battery, I believed it only measures the consumption out of the battery?
 
I've noticed on ICE cars I've owned in the past where I kept detailed fuel data on, that I would always consume more fuel during the colder months than the warmer months. This was just more than letting it idle for a little longer in the mornings (which I didn't do for some since they were kept in a garage). Other than the factors that influenced ICEs in cold weather (like colder denser air requiring more fuel subsequently producing more power as well), my understanding was that due to denser air, it would require more energy to sustain my typical highway driving speeds than in warmer months. Also in the Pacific NW there is quite a bit more precipitation during the colder months and driving on wet roads or through rain will requires more energy as well to travel at the same speeds when it's dry.

There is a noticeable drop in range in my Leaf right now but I am associating it to the increased use of the heater from last month.
 
Drivesolo said:
I've noticed on ICE cars I've owned in the past where I kept detailed fuel data on, that I would always consume more fuel during the colder months than the warmer months.
It is my understanding that a substantial amount of this difference is due to overcooling the engine in the winter. You can increase your mpg by installing an engine heater and partially blocking the air inlet. There is a great deal of discussion about this on PriusChat.
 
Agreed. Assuming no use of Climate Control, it should affect range but have little affect on efficiency (M/Kwh)...

camasleaf said:
I fail to understand how the temperature will affect the mi/kWh unless you have additional electrical load at lower temperatures (climate control, lights, windshield wiper, water on the road, more wind ... edit: tire pressure). I understand that at lower temperature the capacity of the battery will decrease and affect the range, but the mi/kWh should not change.
 
lukati said:
Drivesolo said:
I've noticed on ICE cars I've owned in the past where I kept detailed fuel data on, that I would always consume more fuel during the colder months than the warmer months.
It is my understanding that a substantial amount of this difference is due to overcooling the engine in the winter. You can increase your mpg by installing an engine heater and partially blocking the air inlet. There is a great deal of discussion about this on PriusChat.

Thanks for the tip, however I was talking about factors that were shared from my observations of ICEs to the Leaf.
Drivesolo said:
Other than the factors that influenced ICEs in cold weather (like colder denser air requiring more fuel subsequently producing more power as well),...
 
camasleaf said:
I fail to understand how the temperature will affect the mi/kWh unless you have additional electrical load at lower temperatures (climate control, lights, windshield wiper, water on the road, more wind ... edit: tire pressure). I understand that at lower temperature the capacity of the battery will decrease and affect the range, but the mi/kWh should not change.
There was a long thread on this some months back.

If heater is not being used
- Charging in the garage mitigates any problems with charging when cold
- The battery temperature goes up as we drive

So I think it really comes down to external factors like
- denser air (hard to believe but is possible - afterall that kind of changes the cd)
- wet roads (but wouldn't this actually reduce friction because of hydroplaning ?)

Ofcourse in the last few days I'm using de-frost a lot because of high humidity and frequent fogging (as in every other minute). Infact my Leaf mpk is running at 4.1 (vs 4.6 in Oct and 5.2 in Sep).
 
evnow said:
camasleaf said:
I fail to understand how the temperature will affect the mi/kWh unless you have additional electrical load at lower temperatures (climate control, lights, windshield wiper, water on the road, more wind ... edit: tire pressure). I understand that at lower temperature the capacity of the battery will decrease and affect the range, but the mi/kWh should not change.
There was a long thread on this some months back.

If heater is not being used
- Charging in the garage mitigates any problems with charging when cold
- The battery temperature goes up as we drive

So I think it really comes down to external factors like
- denser air (hard to believe but is possible - afterall that kind of changes the cd)
- wet roads (but wouldn't this actually reduce friction because of hydroplaning ?)

Ofcourse in the last few days I'm using de-frost a lot because of high humidity and frequent fogging (as in every other minute). Infact my Leaf mpk is running at 4.1 (vs 4.6 in Oct and 5.2 in Sep).
I agree that the cold battery pack isn't the main factor in reduced cold weather range for the reasons you state.

If used, the heater would be the biggest drain. If the heater isn't used, the increased drag from cold, dense air and increased rolling resistance from cold tires, cold gears/bearings (lubricant), and wet roads would be the causes of reduced cold weather range. Snow is an even bigger factor in increased rolling resistance and reduced traction efficiency.

It was discussed elsewhere, but wet roads greatly increase rolling resistance versus dry roads (it takes energy to push water away, to channel water through the tire grooves, and to overcome water surface tension, viscosity, and bonding with tires). Tires are designed not to hydroplane so as to retain control, although it can happen briefly at times.

I am surprised that more people don't realize the role that air density plays. There are a number of pilots here at MNL and air density and drag has been discussed before. For driving above about 35 mph and, especially, at highway speeds cold air and drag is a very big deal.
 
Yeah,... we have an interesting bag of weather here in the Pacific NW, don't we. This is the time of year, weather-wise I'm never looking forward to, but I'm taking my vitamin D and keeping positive.

Colder air is denser air and is a factor when calculating the drag force of a body moving through that medium (F= .5 x p x v^2 x Cd x A; where p = density of the fluid, in this case ambient air). The Cd is a property of the car and is essentially constant in summer or winter.

In regards to water on the road, and losses due to the surface being damp is negligible. However when there is enough surface moister to where a vehicle would in put up a spray into the air while traveling on a road; energy is required to displace that water. A modern all-season tire is designed to displace water in the gallons over the course of a few miles. In very loose sense, displacing a lot of standing water (to the point of where some concerned of hydroplaning on the highway begins) means that the tires of a car are acting like big water pumps.
 
I too have seen a drop in KW per mile from 4.1 to 3.6 I reset every month. I have been preheating the car. And temps have been in the low 20's for the past 2 weeks. At departure time, 6am for me. Using an extra 2 bars of battery to get to work, 30 miles one way. I checked tire pressure and it was 30 psi all the way around so I bumped it up to 36 cold. This helped as now I can get to work on 5 bars. Running the heater all the way. The battery temp has been at 4 bars unless I drive it down to the last 2 battery bars (red) then the battery temp jumps up to 5 bars.

When it was raining for 2 days straight had a fogging problem with preheating the car, would get in and have the back windows fogged up. Had to run defrost just to keep from fogging front windows once out on the road. But can see the heater is taking up alot of the range. Heater is running at 3 / 4 kw for 45 minutes that is about 16 miles of range each way. So 32 miles lost to heating the car. So I don't see that range has dropped just that I am using the power to heat the car. So I guess what I am saying is, if I was not heating the car I could still get the same range I was seeing during the summer.
 
My efficiency has been very consistent. I reset my M/Kwh on the center display every month and is has never varied more than one tenth from 4.5 since I picked up the car on March 1st...
 
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