Miles per KWH at highway speeds (65 mph)

[mkjayakumar]

Of course, I am very impressed and very encouraged by what I saw today. Perfect conditions though. 80F with no wind.

 

[GRA]

Of course, I am very impressed and very encouraged by what I saw today. Perfect conditions though. 80F with no wind.

The high temp may explain most of it. The temp was well above ISA, and the density altitude was probably well above your altitude MSL (depending on the atmospheric pressure), decreasing the drag. You may have gained some battery capacity too.

 

[garsh]

I've only had my Leaf a few days. I have a 30-mile commute, and I was hoping to only charge after a round-trip (60 miles). But I live in western PA, so the terrain is fairly hilly, the weather has been pretty cold (~30°F in the morning), I usually have to have my headlights on, and it rains a lot so the windshield wipers have been running half the time.

After charging to 100%, I was down to ~18% after the round trip. I've only been driving 55mph on the highway. I was hoping that I could get away with charging to only 80% regularly, but this now seems unlikely. I haven't used the heater yet. I'm getting about 4.2-4.3 m/kWh. I have to say I'm a bit disappointed.

 

[Reddy]

I had a similar one-time drive, 65 miles at around 30 F. Yes, that was about what I found as well. I didn't get to the low battery warning so I know I had plenty of miles left. Once you get a feel for it, you'll find it will work great. The warming temps will help tremendously. Keep leafing.

Reddy

 

[nosuchthing]

Re: tire pressure.

Leaf tires are rated at 44 psi (the usual). I run them at 38. It is a bad idea to have them at 44. Your center tread will thin out faster then the sides, and your steering will feel too loose. I will lower the pressure to 36 in summer as tires do swell when hot (i.e. increase the pressure). That's why you measure your tire pressure cold and in shade.

And yes, you do get much better mileage with proper pressure. Anytime I take the car in they mess with my tires and they come out at 32. Stupid. 36-38 is the magic number for 44 psi tires. Even though it's not per manufacturer specs.

By the same token, 52 psi tire I would run at 44-46.

 

[DeaneG]

My 12 mile drive into work today gave 4.2m/kWh with a couple hundred feet of elevation loss. The trip back was 3.2m/kWh with the same elevation gain. Both directions around 65mph with little wind.

The Carwings website uses 4.5m/kWh for its calculations for my freeway range. Maybe it thinks it would be funny to make me run out of energy somewhere?

 

[Herm]

After charging to 100%, I was down to ~18% after the round trip. I've only been driving 55mph on the highway. I was hoping that I could get away with charging to only 80% regularly, but this now seems unlikely. I haven't used the heater yet. I'm getting about 4.2-4.3 m/kWh. I have to say I'm a bit disappointed.

Charging to 100% is perfectly ok, as long as you dont let the car sit at 100% for hours.. time at 100% is the detrimental thing.

 

[Herm]

Re: tire pressure.
Leaf tires are rated at 44 psi (the usual). I run them at 38. It is a bad idea to have them at 44. Your center tread will thin out faster

This is not so, modern radials will not wear out at the center when inflated to max sidewall pressures.. but this is not the case for bias-ply tires and perhaps this is where you picked up this obsolete meme.

Inflating to 44psi might give you an extra 10% in range.. try it.

 

[DaveEV]

While the range pretty much matches with Tony chart, the miles/kwh I got was much higher. How is that possible ?

If you were maintaining 4.2 m/kWh, at LBW you should have about 12 miles before turtle and another mile to dead, not 8. The GOM is known to be a bit pessimistic when the battery is low, and optimistic when the battery is high.

Tony's chart also has a couple assumptions:

1. You have a perfectly healthy and full battery capacity available, 21 kWh. Unless you have a GID reading before you leave, it's not possible to verify this.
2. His efficiency numbers are slightly pessimistic in my experience. Maybe his car rolls slightly less efficiently? 80*F temps and any elevation above sea level will help efficiency. On the highway, I also find that traveling in a pack of cars going the same speed improves efficiency, too.

If the 4.2 miles/Kwh was indeed the efficiency, then assuming a conservative 21KWH usable capacity, I should have got a range of 90 miles with sustained speed of 65 mph. But in reality, If I had continued driving at 65mph, I would have got no more than 83 miles. Where did the 7 miles go? battery capacity degradation ?

As mentioned above, if you got 76 miles at LBW, you should have been able to drive about 89 miles, not 83 miles - or basically 90 miles - definitely within the margin of error here. 21 kWh isn't conservative, either - it's pretty much the maximum people see.

Keep in mind that people have found that occasionally the car will go into VLBW and then turtle a few miles earlier than expected (Tony included) so it's best not to rely on the distance beyond VLBW unless you absolutely have to!

 

[LEAFfan]

Try it again with the tires at maximum sidewall pressures, or higher.

I definitely would not recommend that. If you inflate more than 5 psi over the 36, you will lose handling and safety. Check with tire experts if you question this.

 

[planet4ever]

Inflating to 44psi might give you an extra 10% in range.. try it.

Didn't you mean to say 0.10%? :lol:

Note to new readers: Herm is an extremist on this - as on a few other things. Personally, I believe that Nissan has done far more instrumented testing of these tires on this car than any of us will be able to do, and has recommended a pressure that best balances safety, performance, ride, and efficiency. God knows they would have been motivated to push m/kWh as high as it was reasonable to do.

Ray

 

[LEAFfan]

[If there is a topic for this mods please move it, but I couldn't find..]

Now that we all know how much one can get at speeds less than 40 mph, which is around 5.0 miles/kwh, or a range approaching 100 miles to a full charge., I am more interested in knowing what one should expect if I were to drive at a constant highway speed of 65 mph. More than the range, I think the miles/kwh is a better parameter for us to evaluate than the the actual range, because that parameter can tell you with reasonable accuracy how much one can drive on a specific SOC %.

On a test drive today I got 3.8 miles/kwh with the following parameters:

- Cruise control driving at 65 mph
- relatively flat TX 121 in DFW area
- no climate control.
- ECO mode

Is 3.8 miles/kwh a good number for the Leaf ? If so can I assume that on a full charge given that the usable capacity is no more than 21 KWH, I can expect a range of 21*3.8 = 79 miles to VLB ?
Will I get better with or without Cruise control ?
-Jay

My trip was 38 miles at 65mph with Cruise. CC keeps a steady speed as most drivers go below and/or above without it. I had 4.2m/kW h after the 38 miles.

 

[Herm]

You people are so conservative

 

[lpickup]

I've only had my Leaf a few days. I have a 30-mile commute, and I was hoping to only charge after a round-trip (60 miles). But I live in western PA, so the terrain is fairly hilly, the weather has been pretty cold (~30°F in the morning), I usually have to have my headlights on, and it rains a lot so the windshield wipers have been running half the time.

After charging to 100%, I was down to ~18% after the round trip. I've only been driving 55mph on the highway. I was hoping that I could get away with charging to only 80% regularly, but this now seems unlikely. I haven't used the heater yet. I'm getting about 4.2-4.3 m/kWh. I have to say I'm a bit disappointed.

I was going to say give it some time to get used to the car (it took us at least a few weeks to improve our driving habits). But you're getting as good mi/kWh as we are so you're probably already doing fine!

Having said that, you'd be possibly cutting it close, but it seems like you could probably make it on an 80% charge (I would definitely try it out as it warms up).

Keep in mind that by charging to 100% you're not going to benefit much if at all from regen during the early part of your trip, so you're less efficient overall if you charge to 100%. Unless your drive starts with a long uphill climb, you're probably going to gain a few % by not charging to 80%. And even if 80% doesn't quite give you the range, you can get into the habit of charging to 80% and then starting a charge (or pre-heat/cool) 30-45 minutes before your departure time to get you up to 90% (or whatever range makes you feel comfortable).

 

[TonyWilliams]

While the range pretty much matches with Tony chart, the miles/kwh I got was much higher. How is that possible ?

If you were maintaining 4.2 m/kWh, at LBW you should have about 12 miles before turtle and another mile to dead, not 8. The GOM is known to be a bit pessimistic when the battery is low, and optimistic when the battery is high.

Tony's chart also has a couple assumptions:

1. You have a perfectly healthy and full battery capacity available, 21 kWh. Unless you have a GID reading before you leave, it's not possible to verify this.
2. His efficiency numbers are slightly pessimistic in my experience. Maybe his car rolls slightly less efficiently? 80*F temps and any elevation above sea level will help efficiency. On the highway, I also find that traveling in a pack of cars going the same speed improves efficiency, too.

If the 4.2 miles/Kwh was indeed the efficiency, then assuming a conservative 21KWH usable capacity, I should have got a range of 90 miles with sustained speed of 65 mph. But in reality, If I had continued driving at 65mph, I would have got no more than 83 miles. Where did the 7 miles go? battery capacity degradation ?

As mentioned above, if you got 76 miles at LBW, you should have been able to drive about 89 miles, not 83 miles - or basically 90 miles - definitely within the margin of error here. 21 kWh isn't conservative, either - it's pretty much the maximum people see.

Keep in mind that people have found that occasionally the car will go into VLBW and then turtle a few miles earlier than expected (Tony included) so it's best not to rely on the distance beyond VLBW unless you absolutely have to!

A very good summary. Yes, most of the data is intentionally slightly pessimistic, with the assumption that in the future, we'd have better instrumentation. The future is almost here!!!

Balance that pack before a maximum range effort !!!!

 

[mkjayakumar]

Next test run with AC ON

- Distance travelled: 40 miles
- Speed: 65mph on Cruise control
- ECO mode
- Temps: Sunny & 79F

- Miles/kwh seen in the dash: 3.8


Observations:

- From 4.2 to 3.8, that is a penalty of 0.4 miles/kwh for the AC, or around 10 miles range to a full charge.
- also noticed that the energy consumption meter for CC stays around the 0.5 mark.
- Keeping the fans running with AC off, has no noticeable power consumption.
- The range impact on AC would be more at lower speeds, simply because you will be on the road longer with stop lights and such.

 

[TomT]

+1!

Inflating to 44psi might give you an extra 10% in range.. try it.

Didn't you mean to say 0.10%? :lol:

 

[garsh]

I was going to say give it some time to get used to the car (it took us at least a few weeks to improve our driving habits). But you're getting as good mi/kWh as we are so you're probably already doing fine!

I've been keeping the cruise at 55mph on the highway, and putting it into neutral for long downhill runs. Basically, what I was doing in my ICE vehicle before.

And even if 80% doesn't quite give you the range, you can get into the habit of charging to 80% and then starting a charge (or pre-heat/cool) 30-45 minutes before your departure time to get you up to 90% (or whatever range makes you feel comfortable).

I'm currently experimenting with pushing back the charge starting time so that it's not quite fully charged when it's time for me to leave. I thought that would be better for the battery since it will spend less time charged that high. I'll see how close I can get to 80% that way.

 

[TonyWilliams]

Next test run with AC ON

- Distance travelled: 40 miles
- Speed: 65mph on Cruise control
- ECO mode
- Temps: Sunny & 79F

- Miles/kwh seen in the dash: 3.8


Observations:

- From 4.2 to 3.8, that is a penalty of 0.4 miles/kwh for the AC, or around 10 miles range to a full charge.
- also noticed that the energy consumption meter for CC stays around the 0.5 mark.
- Keeping the fans running with AC off, has no noticeable power consumption.
- The range impact on AC would be more at lower speeds, simply because you will be on the road longer with stop lights and such.

Here's how you fix the climate control issue.

Obviously, if you're pulling 0.5 kW for a bit over half an hour, it doesn't account for ten miles. At 4 miles/kWh, that would be 2.5 kWh consumed. What's even more interesting is that ECO mode should reduce A/C.

The bottom line, you're truncating your efforts to get data, and that leaves us with lots o'splaining to do.

 

[LEAFfan]

Next test run with AC ON

- Distance travelled: 40 miles
- Speed: 65mph on Cruise control
- ECO mode
- Temps: Sunny & 79F

- Miles/kwh seen in the dash: 3.8


Observations:

- From 4.2 to 3.8, that is a penalty of 0.4 miles/kwh for the AC, or around 10 miles range to a full charge.
- also noticed that the energy consumption meter for CC stays around the 0.5 mark.
- Keeping the fans running with AC off, has no noticeable power consumption.
- The range impact on AC would be more at lower speeds, simply because you will be on the road longer with stop lights and such.

I never have that much of a penalty in the summer. You must have your A/C temp really low. For me, it isn't necessary to make ice cubes in the car. Above 80 degrees keeps both of us plenty cool and it uses a negligible amount of energy. Also, I always obtain more range (much higher) with A/C at lower speeds than freeway speeds. I have no idea how you arrived at that last conclusion. You can't coast in 'N' on relatively flat freeway, but you sure can coast up to the lights (1/4-1/2 mile) which will give you a huge increase on range.