130 mile mountain trip turned into 180 mile success!

[LeftieBiker]

Good going!

 

[SageBrush]

Fantastic, and I'm happy to be proven wrong.
How fast did you travel from Montrose to Gunnison ? Any wind that day ?

 

[IssacZachary]

Fantastic, and I'm happy to be proven wrong.
How fast did you travel from Montrose to Gunnison ?

Proven wrong? Without your calculations I wouldn't have even tried it!

From Montrose to Gunnison is the stretch I really creeped. I went 40mph max until I was getting close to Gunnison and saw I was going to make it just fine, then went 55mph.

On the way to Montrose I went mostly 50mph. But I also ended up having to use the defroster the whole way because it was between 22*F and 30*F in the morning and the windows kept fogging! I also had brought my wife along!

Speed limits range from 35mph to 65mph between Montrose and Gunnison with one 25mph curve too.

 

[SageBrush]

From Montrose to Gunnison is the stretch I really creeped. I went 40mph max until I was getting close to Gunnison and saw I was going to make it just fine, then went 55mph..

Smart.
Did the calcs work out as expected with the slower speeds taken into account ?

Excuse my nosy nature, but I have to ask: why did your wife join you ?
Mine would have, if only to say "I told you so!!" if the battery ran dry.

 

[IssacZachary]

From Montrose to Gunnison is the stretch I really creeped. I went 40mph max until I was getting close to Gunnison and saw I was going to make it just fine, then went 55mph..

Smart.
Did the calcs work out as expected with the slower speeds taken into account ?

Excuse my nosy nature, but I have to ask: why did your wife join you ?
Mine would have, if only to say "I told you so!!" if the battery ran dry.

The calcs worked out very well. I calculated from peak to peak like you said, and wrote the results down on a paper. That way when I got to the top of each section I could reference my calculations and see how close I was. I found that 4.5 miles per kWh at 50mph is pretty darn close! And the .5kWh per 300ft rise is too. And even the 5.9 miles per kWh at 40mph is too! At least they are with the guess that I have 20kWh in my battery. LeafSpy would confirm this better. Actually, I used a bit less, ending up with almost twice left over (i.e. 34% instead of 19%, 21% instead of 10%) of what I had predicted in the end. But I think this may be contributed to 1 altitude, 2 not always going my top speed because of lower speed limits and 3 gaining back more on downhill slopes than originally calculated.

And that's what seemed to play around more, the downhill calculations. It seems that if the slope is not steep then you gain nearly the same 0.5kWh for every 300ft going down that you lose every 300ft going up. But the steeper it is and the more you have to use regen then the less you gain back. On the steepest part I actually apparently gained back less than half! But since there are many slopes that are just steep enough that I can maintain my speed by simply shifting into neutral over all I ended up regaining more than half of 0.5kWh per 300ft.

My wife went along because she always likes to go with me and because she wanted to do some shopping in Montrose. Ideally, if there were a charging station in Delta, I could have made it all the way there on one charge, done my thing there, which took almost 4 hours, came back to Montrose and topped off there while shopping, and have made it home in less than 1.5 times it would have taken me I'm an ICEV to do all that (do to driving slower, not charging). But having to charge in Montrose on the way there to make up for the lack of charging in Delta added more time.

If I could cut my aerodynamic drag to the same as the AeroCivic (0.17Cd) I could go about 10 to 15mph faster and use the same amount of energy.

 

[SageBrush]

Awesome. Thanks for the detailed report

 

[VitaminJ]

Yeah I gotta say the calculation you came up with, SageBrush, is pretty dang good approximation. It's slightly conservative but that's what you want anyway. I did my commute to work and it came out almost exact. I'm gonna use it for some mountain trips I have planned. According to your calculations I shouldn't be able to drive to the top of Mt. Evans not even close. But another Leaf owner was able to drive there from City Park in Denver in a 30kwh Leaf which is about 25 extra miles than from my house to Mt. Evans. How did you come to settle on these calcs?

 

[SageBrush]

Vitaminj, the description is earlier in this thread but in summary:
Energy expended is from level ground driving + elevation change
Elevation change = mgh
Elevation change is conserved (presuming no brakes use)

So from start to the first peak;
and from each peak to the next,
I imagine as right triangles in successsion

As IsaacZachary points out though, the 4.5 miles per kWh on level ground presumes a leisurely speed. You are quite right that when it came time to round numbers I erred on the conservative side.

 

[alozzy]

Out of curiousity, I typed the following values into EV Trip Planner (used Leaf "Beta" profile):

Speed multiplier: 1.0
Cabin temp: 70F
Ext temp: 30F
Payload: 350lb
Wind: 0
Initial charge: 100%
Buffer charge: 15%

This is what EV trip planner calculates for the one way trip from Gunnison to Montrose:

Distance: 64.4 miles
Driving time: 1:15
Total energy used: 13.6 kWh
Average efficiency: 211 Wh/mile (works out to 4.7 miles/kWh)

For the reverse trip from Montrose to Gunnison, I changed only the speed multiplier (to 0.9), as @IssacZachary mentioned he drove conservatively on the way back:

Distance: 64.4 miles
Driving time: 1:25
Total energy used: 18.9 kWh
Average efficiency: 294 Wh/mile (works out to 3.4 miles/kWh)

@IssacZachary - this sounds fairly accurate, as you mentioned that you had 34% battery when you arrived in Montrose and (20 - 13.6)/20 = 32%. For the return journey, (20 - 18.9)/20 = 6% seems way off, as you mentioned you had 21% battery left. Weird how it seems accurate one way but not the other.

I'm not trying to be a smart ass, I appreciate SageBrush's work, but I'm honestly too lazy/stupid to do the calculations myself when planning a trip. I think I'm going to do a trip to Whistler, BC soon, so I'm going to use EV trip planner to estimate, then see how accurate it is. It would be so nice if it proves to be accurate, as it only takes a few seconds to generate the estimates.

 

[VitaminJ]

Vitaminj, the description is earlier in this thread but in summary:
Energy expended is from level ground driving + elevation change
Elevation change = mgh
Elevation change is conserved (presuming no brakes use)

So from start to the first peak;
and from each peak to the next,
I imagine as right triangles in successsion

As IsaacZachary points out though, the 4.5 miles per kWh on level ground presumes a leisurely speed. You are quite right that when it came time to round numbers I erred on the conservative side.

I saw the description but I didn't see how you settled on the .5kwh/300 ft figure. Is that from your own experience or did you calculate it?

 

[IssacZachary]

Out of curiousity, I typed the following values into EV Trip Planner (used Leaf "Beta" profile):

Speed multiplier: 1.0
Cabin temp: 70F
Ext temp: 30F
Payload: 350lb
Wind: 0
Initial charge: 100%
Buffer charge: 15%

This is what EV trip planner calculates for the one way trip from Gunnison to Montrose:

Distance: 64.4 miles
Driving time: 1:15
Total energy used: 13.6 kWh
Average efficiency: 211 Wh/mile (works out to 4.7 miles/kWh)

For the reverse trip from Montrose to Gunnison, I changed only the speed multiplier (to 0.9), as @IssacZachary mentioned he drove conservatively on the way back:

Distance: 64.4 miles
Driving time: 1:25
Total energy used: 18.9 kWh
Average efficiency: 294 Wh/mile (works out to 3.4 miles/kWh)

@IssacZachary - this sounds fairly accurate, as you mentioned that you had 34% battery when you arrived in Montrose and (20 - 13.6)/20 = 32%. For the return journey, (20 - 18.9)/20 = 6% seems way off, as you mentioned you had 21% battery left. Weird how it seems accurate one way but not the other.

I'm not trying to be a smart ass, I appreciate SageBrush's work, but I'm honestly too lazy/stupid to do the calculations myself when planning a trip. I think I'm going to do a trip to Whistler, BC soon, so I'm going to use EV trip planner to estimate, then see how accurate it is. It would be so nice if it proves to be accurate, as it only takes a few seconds to generate the estimates.

Interesting. I calculated I'd get into Montrose with 20% and into Gunnison with 10%. So it was closer to Montrose but less accurate to Gunnison.

 

[alozzy]

Yup, I followed your earlier link and noticed you were using the Leaf Alpha profile, so out of curiosity I tried the Beta profile

 

[SageBrush]

Calculated.

m * g * h (rounded)

 

[SageBrush]

But the steeper it is and the more you have to use regen then the less you gain back. On the steepest part I actually apparently gained back less than half! But since there are many slopes that are just steep enough that I can maintain my speed by simply shifting into neutral over all I ended up regaining more than half of 0.5kWh per 300ft.

Yep.
Regen is unlikely to return more than half of the kinetic energy bled off the car.

The mountains I drive in can be handled by approaching the peak at a slow speed; then I usually do not use the brakes. Of course this only works if traffic is not impeded.

 

[LeftieBiker]

The highest figure I've seen quoted for energy regained through regen is 39%.

 

[dhanson865]

If I could cut my aerodynamic drag to the same as the AeroCivic (0.17Cd) I could go about 10 to 15mph faster and use the same amount of energy.

It won't get you to 0.17 but if you want a range increase the easy fix is to swap the OEM wheels for the lightest 15" wheels you can get and put LRR 15" tires on them.

I got Honda Civic Hybrid wheels and had the center bore enlarged 2mm to fit the hub on the Nissan. Took my daily driving from 4.4 miles per kWh to 5.1 miles per kWh (though the old tires weren't LRR).

You can play around with closing the OEM rims with aero mods but you'll gain way more by cutting weight using lower diameter rims and the resultant lower weight tires that go on them.

I went for Dunlop Enasave 01 A/S but if you want you can do the Michelin Energy Saver they are clearly a copy of.

Oh and in case no on has hit you over the head with this yet, put more air in your tires. Cheapest mod you can do to extent range. I won't drive a car with PSIs below 40 now (I've driven at 51 psi for some time on the Prius and have played around at various PSI between 40 and 50 on the Leaf.)

 

[GRA]

Calculated.

m * g * h (rounded)

If that's too cryptic, I use (weight of the vehicle plus pax/cargo in kg) x g (9.8m/s) x 304.8m (1,000 feet) = energy used for the climb in joules / (3.6 x 10^6) = energy used in kWh, which at typical LEAF weights will give you around 1.5 kWh/1,000' of climb. Sagebrush is using a rounded value of .5 kWh/300 feet, which is close enough (a bit conservative) given all the other variables. Normally I just multiply the weight in kg by 2,989 (9.8... x 304.8...).

Example:

Gross vehicle weight (mass) 3,700 lb (say 3,400 lb. for the car, plus 300 lb. load) / 2.2046 (conversion to kg.)= 1,678 kg.

1,678 kg. x 2,989 = 5,016,466 joules (mass in kg.) x ((g in meters/second) x (1,000' height / 3.28083333 ft./m))

5,016,466j / 3.6 x 10^6 (or 3,600,000; converts joules to kWh) = 1.39 kWh/1,000 feet of climb

 

[SageBrush]

If I could cut my aerodynamic drag to the same as the AeroCivic (0.17Cd) I could go about 10 to 15mph faster and use the same amount of energy.

It won't get you to 0.17 but if you want a range increase the easy fix is to swap the OEM wheels for the lightest 15" wheels you can get and put LRR 15" tires on them.

I got Honda Civic Hybrid wheels and had the center bore enlarged 2mm to fit the hub on the Nissan. Took my daily driving from 4.4 miles per kWh to 5.1 miles per kWh (though the old tires weren't LRR).

You can play around with closing the OEM rims with aero mods but you'll gain way more by cutting weight using lower diameter rims and the resultant lower weight tires that go on them.

I went for Dunlop Enasave 01 A/S but if you want you can do the Michelin Energy Saver they are clearly a copy of.

Oh and in case no on has hit you over the head with this yet, put more air in your tires. Cheapest mod you can do to extent range. I won't drive a car with PSIs below 40 now (I've driven at 51 psi for some time on the Prius and have played around at various PSI between 40 and 50 on the Leaf.)

Good advice, but don't try this in the Colorado mts in the winter.

 

[IssacZachary]

Calculated.

m * g * h (rounded)

If that's too cryptic, I use (weight of the vehicle plus pax/cargo in kg) x g (9.8m/s) x 304.8m (1,000 feet) = energy used for the climb in joules / (3.6 x 10^6) = energy used in kWh, which at typical LEAF weights will give you around 1.5 kWh/1,000' of climb. Sagebrush is using a rounded value of .5 kWh/300 feet, which is close enough (a bit conservative) given all the other variables. Normally I just multiply the weight in kg by 2,989 (9.8... x 304.8...).

Example:

Gross vehicle weight (mass) 3,700 lb (say 3,400 lb. for the car, plus 300 lb. load) / 2,2046 (conversion to kg.)= 1,678 kg.

1,678 kg. x 2,989 = 5,016,466 joules (mass in kg.) x ((g in meters/second) x (1,000' height / 3,28083333 ft./m))

5,016,466j / 3.6 x 10^6 (or 3,600,000; converts joules to kWh) = 1.39 kWh/1,000 feet of climb

Awesome! Thank you!

I had already figured out aerodynamic drag (force = velocity squared x coefficient of drag x cross-sectional area x density of air). Rolling resistance is more of a guess to me because of all of the variables. Then all that's left is efficiencies and auxiliary power. Oh! And momentum too of course.

If I could cut my aerodynamic drag to the same as the AeroCivic (0.17Cd) I could go about 10 to 15mph faster and use the same amount of energy.

It won't get you to 0.17 but if you want a range increase the easy fix is to swap the OEM wheels for the lightest 15" wheels you can get and put LRR 15" tires on them.

I got Honda Civic Hybrid wheels and had the center bore enlarged 2mm to fit the hub on the Nissan. Took my daily driving from 4.4 miles per kWh to 5.1 miles per kWh (though the old tires weren't LRR).

You can play around with closing the OEM rims with aero mods but you'll gain way more by cutting weight using lower diameter rims and the resultant lower weight tires that go on them.

I went for Dunlop Enasave 01 A/S but if you want you can do the Michelin Energy Saver they are clearly a copy of.

Oh and in case no on has hit you over the head with this yet, put more air in your tires. Cheapest mod you can do to extent range. I won't drive a car with PSIs below 40 now (I've driven at 51 psi for some time on the Prius and have played around at various PSI between 40 and 50 on the Leaf.)

Yes, I put 42psi in the tires. I don't have low rolling resistance tires though. I'd like to get some. Michelin also offers a winter LRR tire. Sometime in the future I'd like to get two sets of rims and put summer LRR tires on one and winter LRR tires on the other.

I'm not so sure how much smaller and lighter rims would help for highway/content speed driving. It would seem to me that it would be helpful in stop 'n go traffic, but not so much at constant velocities.

Technically speaking, greater rotating mass could actually improve overall efficiency in hilly terrain where the car is speeding up going down hills and slowing down going up hills.

I bring up the AeroCivic and it's 0.17Cd because it only cost it's owner $400 to drop the Cd by 0.14 (0.31 to 0.17). That's really cheap for the amount of benefit gained! The AeroCivic is also similar to the Leaf in being a hatchback. To me there's too many similarities between the Leaf and the Civic to say that 0.17Cd on a Leaf is impossible.

The effects of aerodynamic drag are very noticeable. What we do know is that the energy-per-mile needed for rolling resistance doesn't hardly change with speed. Accessories actually use less energy-per-mile the faster you go. But the energy-per-mile needed to combat air drag does change noticeably, and it changes exponentially. And it is also the biggest energy user.

 

[SageBrush]

I'm not so sure how much smaller and lighter rims would help for highway/content speed driving. It would seem to me that it would be helpful in stop 'n go traffic, but not so much at constant velocities..

My thought as well.

By the way ...
m*g*h for potential energy might look obscure, but it has a much more recognizable form:
Work = force * distance

h = distance (up)
Force = m*g