Nissan LEAF - It IS the car for me!

[Frank]

Nice videos. I did the math. When you pulled out of the driveway at the start of your 30 mile drive the remaining miles were 81. When you returned after 30 miles of combined highway and slower speed driving the remaining miles were 78 (because the Leaf was put into ECO mode and theoretically could get 78 miles out of the pack). So to travel 30 miles you used 3 miles of the Leaf's range?

 

[mwalsh]

Nice videos. I did the math. When you pulled out of the driveway at the start of your 30 mile drive the remaining miles were 81. When you returned after 30 miles of combined highway and slower speed driving the remaining miles were 78 (because the Leaf was put into ECO mode and theoretically could get 78 miles out of the pack). So to travel 30 miles you used 3 miles of the Leaf's range?

Our range left when we got back to Nissan was actually ~65 miles. Since I discounted the immediate 9 mile loss from 90 miles to 81 miles, I figured we'd done 30 miles using 16 miles of range. If that's even the proper way the figure it. Otherwise we'd done 30 miles using 26 miles of range. That's without really considering any benefit from ECO.

BTW, the 30 mile all freeway segment...we started with 60 miles of range; had our immediate loss of 9 miles, taking us to 51 miles; and finished with 19 miles. So that's either 30 miles on 32 miles of range. or 30 miles on 42 miles of range, depending on how you figure it.

I think it's still too preliminary to make massive conclusions until more real world data starts coming in.

Edit: Also, BTW, when my memory card ran out we had about 5 miles to go and we we're showing 70 miles of range left. We got back to Nissan with ~65 miles left......after driving 5 miles.

 

[evnow]

Range left is essentially showing how much you can drive if you drove the same way you have been doing for the immediate 10 seconds (or some such small interval).

That is why as soon as you accelerate, the range drops. Not sure this is the best way to calculate range - I'm sure the algorithms will improve as EVs mature.

 

[mwalsh]

I think the main (yet only preliminary) observations to be made from the videos are:

1) Driving at a steady 50-55mph may well be the way to maximize range.
2) Steady driving at freeway speeds is still going to give you respectable range.
3) Terrain is everything.

 

[EVDRIVER]

50-55 is the best freeway speed for an EV, after that drag goes up exponentially. The original Think was regulated to 58 MPH. All the Leaf calculations should be taken with a grain of salt, the best way to estimate range is to be at a constant speed for some time and see actual kw consumption in real time. I want to see real time kw usage of the car at a given speed and reaming pack kwh, that tells all. This also assumes the capacity remains accurate.

 

[cdub]

Range left is essentially showing how much you can drive if you drove the same way you have been doing for the immediate 10 seconds (or some such small interval).

That is why as soon as you accelerate, the range drops. Not sure this is the best way to calculate range - I'm sure the algorithms will improve as EVs mature.

I think this is pretty much the ONLY way to calculate range. The car has no way of knowing how you'll be driving in the future. It can only know how you're driving right now and how much range you'll get from that point on.

 

[SanDust]

I think the main (yet only preliminary) observations to be made from the videos are:

1) Driving at a steady 50-55mph may well be the way to maximize range.
2) Steady driving at freeway speeds is still going to give you respectable range.
3) Terrain is everything.

Since going up a slope is the same thing as accelerating -- no difference going up a 20 degree slope and accelerating at .2g -- #1 and #3 are more or less the same. For #2 speed makes a big difference. The power needed to overcome drag goes up with the cube of the velocity, so you need roughly 2.75X the power at 70 MPH as you do at 50 MPH. At 90 MPH you'd need 5.8X more power. Regardless of how steady it is, very high speeds will kill range.

I'd also suggest that extreme temperature will take a huge bite from range since other than aerodynamics that's the biggest power grabber.

 

[tps]

The power needed to overcome drag goes up with the cube of the velocity, so you need roughly 2.75X the power at 70 MPH as you do at 50 MPH. At 90 MPH you'd need 5.8X more power. Regardless of how steady it is, very high speeds will kill range.

I'd also suggest that extreme temperature will take a huge bite from range since other than aerodynamics that's the biggest power grabber.

But the energy (kWh) needed to overcome drag goes up as the sqaure of velocity; since the range is based on energy, not power, the range doesn't get killed so fast as you imply (but still fast enough). If you doubled the velocity, 4X the energy (kWh) would be required, but it would take 8X the power (kW) since the work would be done in half the time.

 

[evnow]

I think this is pretty much the ONLY way to calculate range. The car has no way of knowing how you'll be driving in the future. It can only know how you're driving right now and how much range you'll get from that point on.

Hmmm ... not really.

There are various ways of using history to predict the nature of driving in the future. For eg. we know when someone accelerates from 0, the car uses a lot of energy. But the acceleration will stop at some point and the energy usage reduces. So, no point in reducing the range suddenly when someone accelerates from zero.

I'm sure even a couple of math graduate students can come up with good algorithm that predicts the range better.

Afterall they have Windows CE running there. Make use of it !

 

[SanDust]

But the energy (kWh) needed to overcome drag goes up as the sqaure of velocity; since the range is based on energy, not power, the range doesn't get killed so fast as you imply (but still fast enough). If you doubled the velocity, 4X the energy (kWh) would be required, but it would take 8X the power (kW) since the work would be done in half the time.

I agree with most of what you're saying but I think you're confusing energy and power. They're not interchangeable. Energy doesn't overcome the force of drag. Power, which is the rate at which energy is used, does.

You're bringing up a related but different point which would be that since range is related to velocity and time, for a given unit of time a vehicle moving at a higher velocity will travel further than a vehicle moving at a lower velocity. So while a vehicle moving at a higher velocity will use energy at a higher rate per unit time, it will also travel further per unit time. Or I think this is what you're saying. Yes? No?

 

[mwalsh]

Here is TFLcar's review. It'll give you a further idea of the terrain in the area we drove.

[youtube]http://www.youtube.com/watch?v=u1U3X5rYtlA[/youtube]

 

[tps]

You're bringing up a related but different point which would be that since range is related to velocity and time, for a given unit of time a vehicle moving at a higher velocity will travel further than a vehicle moving at a lower velocity. So while a vehicle moving at a higher velocity will use energy at a higher rate per unit time, it will also travel further per unit time. Or I think this is what you're saying. Yes? No?

I'm saying that while drag increases required power (kW) by the cube of the velocity (mph), it increases the total energy (kWh) used to go a given distance (m) by the square of the velocity(mph). If you double the velocity (mph), 8X the power (kW) is required for half as long (h), so 4X the energy (kWh) is used. Neglecting losses other than drag, the vehicle's range would be inversely proportional to the square of it's velocity.

 

[occ]

Mwalsh, thanks for the TFLcar review video:

"...underwhelm because it like an appliance,... no engine!"

Heck, that to me is the best part! We're finally breaking away from the dinosaur age of personal transportation. Once I get my LEAF, I will feel sooooo free from the grip of the oil company!

 

[mwalsh]

Heck, that to me is the best part! We're finally breaking away from the dinosaur age of personal transportation. Once I get my LEAF, I will feel sooooo free from the grip of the oil company!

I've said all along that all this car needs to be for me is a "commuting appliance". That it is so much more than that is just icing on the cake.

 

[LEAFguy]

mwalsh, thanks for the info in your writeup. Anytime real-world usage can be presented, it can be useful to others.

 

[malloryk]

yes, thanks for the review! I'm glad that someone from the forum got to go. Keep the info coming!

 

[lne937s]

Considering that the Juke gets quicker to 60 by a second and a half with traction control off versus on (over 17% reduction), it looks like it is pretty restrictive and makes a big difference in these Oppama-built cars. If you figure another half a second for removing the passenger (5% reduction) and ~10 seconds to 60 would potentially become ~7.8 seconds to 60 (22% reduction) just driver and no traction control...

http://nissan-leaf.net/2010/11/01/first-drive-nissan-leaf-net-tests-the-2011-juke/

 

[mwalsh]

Considering that the Juke gets quicker to 60 by a second and a half with traction control off versus on (over 17% reduction), it looks like it is pretty restrictive and makes a big difference in these Oppama-built cars. If you figure another half a second for removing the passenger (5% reduction) and ~10 seconds to 60 would potentially become ~7.8 seconds to 60 (22% reduction) just driver and no traction control...

I'm only willing to concede a 9 second 0-60 at this point. But I'm willing to give it another try....alone, with the AC and TC off.

 

[Coffee_Slurry]

Give me two minutes in the car with my Race Tech DL1 and you'll have accurate numbers, graphs.. I can't believe that out of ALL the professional journalists, nobody brought an accelerometer. Is there an embargo on publishing performance specs?

 

[evnow]

Give me two minutes in the car with my Race Tech DL1 and you'll have accurate numbers, graphs.. I can't believe that out of ALL the professional journalists, nobody brought an accelerometer. Is there an embargo on publishing performance specs?

I'm guessing Nissan wouldn't let anyone connect anything ...