LEAF 2018 151 Mile Range Mystery

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SageBrush

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Joined
Mar 6, 2011
Messages
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Location
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The EPA range calculation is IIRC based on 55% city, 45% highway driving.
Since the LEAF 2018 is within 1 MPGe in both city and highway and has the same combined MPGe compared to the 30 kWh Model from 2017,

And the 30 kWh LEAF is rated at 107 miles EPA range,
We should expect the 40 kWh Model to have (4/3)*107 = 142.6 miles of range, yet it is rated for 151 miles.
The extra 8.4 miles is close to 3 kWh.

Anybody know where they are ?
Undisclosed in the new model ?
Missing in the 30 kWh model ?
 
Sagebrush, you have been around for a while now...

First, you should know about all that EPA "your mileage may vary" crap...

Second, if we calculate numbers based on the Current Leaf, which was rated at 24kwh..... It only has about 21 kwh available.

So the 40kwh battery will logically have only 37 kwh available. So at 4.5miles /kw x 37 kwh = 166.5 miles range (*****up to turtle or 0% battery).

Even if you use a more conservative 4.0 miles /kw x37 kwh miles range, you get 148 miles range. (or 2 miles less than the estimate....) Is that not close enough for you?? :)

IN REALITY.... No one should even be expecting that range, because that number of miles would bring the battery down to turtle mode.... Right?

A more realistic expectation would be getting between 4-4.5 miles per kilowatt. If you use the battery down to a more reasonable 20%, then the following would be reasonable..

40KWH (total battery) - 3kwh (unused overhead) - 37kwh (usable)

37kwh X 80% (true used power, allowing for leaving 20% battery capacity (RESERVE)) = 29.6 KWH used per charge.

So a 40 KWH Leaf would realistically get between :

29.6 kwh x 4.0 miles/kw = 118.4 miles per charge (conservative) to 29.6 kwh X 5.0 miles/ kw = 148 miles range per charge.

I think 4.5 miles/kw is reasonable = 133.2 REALISTIC MILES OF RANGE ON THE 2018 LEAF......
 
EPA numbers for my 2015 are higher than the 2011 even though battery is the same size. Steady speed range is essentially the same (with no battery deterioration) so the actual battery capacity and steady speed efficiency are about the same. Regeneration on the 2015 is more aggressive than the 2011 so real world city driving range is higher for the 2015 and that is reflected in the EPA numbers. Nissan claims even more aggressive regeneration for the 2018 with "single pedal" driving so that likely improves the real world city driving efficiency enough to account for the difference in EPA numbers vs. calculation for increased battery capacity. The new body style might be slightly more aerodynamic, but I have not seen any drag coefficient and frontal area comparisons.
 
Driver experience is irrelevant here.
I just used the EPA MPGe numbers.

Apples to Apples
 
I thought the 2018 LEAF has an improved drag coefficient, thought I read that somewhere. If so, that might explain part of it too
 
Just found it...

Cd on 2017 LEAF is .32 Cd

Apparently, the Cd on 2018 LEAF is 0.28

So, range benefit should be somewhat less than (0.32/0.28) or 14%, although at highway speeds, aero drag accounts for most of the total losses.
 
SageBrush said:
Folks,
The MPGe are a given from the EPA -- regardless of the hows and whys.

Alright then, back to your original comment...

We should expect the 40 kWh Model to have (4/3)*107 = 142.6 miles of range, yet it is rated for 151 miles. The extra 8.4 miles is close to 3 kWh

Improvement in Cd fully explains that...
 
alozzy said:
SageBrush said:
Folks,
The MPGe are a given from the EPA -- regardless of the hows and whys.

Alright then, back to your original comment...

We should expect the 40 kWh Model to have (4/3)*107 = 142.6 miles of range, yet it is rated for 151 miles. The extra 8.4 miles is close to 3 kWh

Improvement in Cd fully explains that...
The difference in Cd does not explain the discrepancy.


Consider this thought experiment:
EV A:
Has a specific MPGe on a drive cycle with C kWh capacity that results in R range.
Nothing else is known about the car.

EV B:
Has the same MPGe on the same drive cycle, but has 1.33*C battery capacity
Nothing else is known about the car.

Can you calculate the range of Car B in terms of R on this drive cycle ? To what accuracy ?
 
1) EPA actually tests 1 in 7 new cars on average each year which means 85% of the EPA ratings are taken directly from the Manufacturer's mouth (which probably accounts for several lawsuits past and present over MPG claims)

2) Generally DoD for LEAF has been roughly 93.6-94% for more durable 24 kwh packs (btw, they have changed slightly in size) or nearly 95% for the less capable 30 kwh packs.

3) If using the 30 kwh LEAF as a guideline and its 29.6 kwh pack; with the 28.1 kwh usable we are seeing 3.8 miles per kwh. If using that same figure that equates to 39.7 kwh usable which is not realistic.

4) Using a realistic DoD of 94% along with prelim LEAF Spy measurements putting pack at roughly 40.68 kwh AND a 4 mile per kwh average which should be easy to do since we have better aero, etc we get about 38 kwh usable AND the 151 mile estimate.


I think this is a low ball figure.
 
alozzy said:
SageBrush said:
Folks,
The MPGe are a given from the EPA -- regardless of the hows and whys.

Alright then, back to your original comment...

We should expect the 40 kWh Model to have (4/3)*107 = 142.6 miles of range, yet it is rated for 151 miles. The extra 8.4 miles is close to 3 kWh

Improvement in Cd fully explains that...

So why didn't the MPGe change?
 
It is odd that the MPGe doesn't match the range, but MPGe is really only useful for comparing ICE cars to EVs. Converting MPG to MPGe assumes each gallon of gas is equivalent to 33.7 kWh of energy.

EVs should really be rated based on a stated miles per kWh efficiency, and the total useable kWh pack capacity, to arrive at a useable range.

For example, if the 2018 LEAF averages 4 miles per kWh on a standardized track loop, and the total useable pack capacity is 37.5 kWh, then the range rating should be 150 miles. It would be pretty easy for the EPA to measure actual KWh efficiency, rather than is MPGe nosense.
 
alozzy said:
It is odd that the MPGe doesn't match the range, but MPGe is really only useful for comparing ICE cars to EVs. Converting MPG to MPGe assumes each gallon of gas is equivalent to 33.7 kWh of energy.

EVs should really be rated based on a stated miles per kWh efficiency, and the total useable kWh pack capacity, to arrive at a useable range.

For example, if the 2018 LEAF averages 4 miles per kWh on a standardized track loop, and the total useable pack capacity is 37.5 kWh, then the range rating should be 150 miles. It would be pretty easy for the EPA to measure actual KWh efficiency, rather than is MPGe nosense.

MPGe is a standardized measure of energy. We "should" be able to compare it from EV to EV.

Maybe the LEAF Spy reading was low and we have a 42-43 kwh pack? :) I'd rather go with that!
 
alozzy said:
EVs should really be rated based on a stated miles per kWh efficiency, and the total useable kWh pack capacity, to arrive at a useable range.
The combined EPA city/highway efficiency result for both the 30 kWh and 40 kWh models is 301 Wh per mile.
In your preferred units, 3.32 miles per kWh

How do I know this ? It says so, right on the window sticker. But it as written as miles per 33.7 kWh instead of miles per one kWh
----
The EPA does its testing as follows:
The car is charged to full;
Driven on the test cycles until it stops;
then the kWh at the meter to charge it to full is measured.
The distance driven divided by the energy (kWh) at the meter consumed, multiplied by 33.7 gives the MPGe

You should feel quite free to divide the MPGe by 33.7 to get your miles/kWh rating.

---
Which brings us back to my original question:
Since both models have the same 3.32 miles per kWh rating,
one might expect that the "40 kWh" model to have 4/3rds (133%) the range as the "30 kWh" model
But it actually has 141% the range.

Presuming the efficiency label is correct, there is unstated capacity differences.
By my arithmetic,
The '30 kWh' Model has 28 kWh usable
The '40 kWh' Model has 39.7 kWh usable

If we presume that both batteries have ~ 2 kWh reserved against bricking and over charging, the actual capacities are
30 kWh in the '30 kWh' model
and 41.7 kWh in the '40 kWh' model
 
@DaveinOlyWA I agree that MPGe is the current standard, I just differ with you on whether it should be the standard. I don't think it makes any sense to use MPGe as a comparison between EVs. Why convert kWh efficiencies to MPG equivalent when neither vehicle burns gasoline? Especially when kWh/mile or miles/kWh comparisons are so much easier to derive for EVs...

If the EPA focused on kWh/mile or miles/kWh instead of MPGe for EVs, it would provide EV buyers with better information. For example, if they stated that an EV ended up with an efficiency of 4.2 miles/kWh on their test rack, and that the usable pack energy was 58 kW, educated EV buyers wouldn't just think "Ok, it'll have 244 miles of range" - they would extrapolate from that efficiency rating, based on their own experiences driving an EV (i.e. I drive more/less conservatively than most EV drivers, I have to deal with harsh winters or hot summers, etc), and would have a good sense of what "real world" range would be for their circumstances.
 
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