3 or 4 miles/kWh?

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V

Vandervecken

Member
Joined
Nov 8, 2022
Messages
5
Hey folks,
Pretty new to Leaf Spy, and discovered that my rough efficiency is 3 miles per kWh. Leaf Spy pro, and the Leaf itself (I have a 2013 model) seem to calculate miles of range based on 4 miles/kWh. Is this normal? Is it normal that the real efficiency is around 3, even though the official value is 4?

Thanks in advance for helping out a newbie!
 
Welcome to the forum. Pretty common, yes. I still get about 3.5 in colder weather. If your tires aren't at about 40psi, inflating them to that will raise your efficiency enough to notice. If the tires aren't rated Low Rolling Resistance (LRR) then that exacts a penalty in mileage. And if you drive an S with no heat pump, that causes a real hit to efficiency in milder Winter weather.
 
Leaf Spy Pro should have a +/- button for you to adjust what your miles per kWh is so that it can predict your range based upon that.

I don't know of "official value is 4" for miles per kWh. If you're talking about the guess-o-meter (the silly number on the right side), that should pretty much be ignored.
 
Leaf Spy Pro should have a +/- button for you to adjust what your miles per kWh is so that it can predict your range based upon that.
Click to expand...

LeafSpy DOES have this button, lower right on the main page you can raise or lower the range prediction using actual m/kWh. It has some confusing options (scrolls thru various different parameters) but one of them allows you to input info and predicts a range. I don't use it but it is there.
 
If that 2013 is an SV or SL, then it has a fairly good range estimator built into the Nav system. It uses the actual driver's efficiency, IIRC, and overlays a map with two concentric circles. The larger circle is the too-optimistic Guess O Meter's estimate, but the smaller circle is the Nav system's more accurate estimate of current range. You bring that up, IIRC, by pressing the blue Energy button on the steering wheel in the gen 1 and 1.5 Leaf.
 
OP, there are facts and there are guesses

Facts first: The pack can measure the voltage, and it has a current (coulomb) counter. Those measurements let it derive with fair accuracy the total energy stored in the pack when completely charged, or when the pack is part-way depleted.

But many EV owners do not understand 'energy capacity.' They just want to know if they can make it to their destination some distance away. The 'solution' (AKA guess) is to calculate the product of the energy remaining (in kWh) and some presumed miles/kWh. The miles/kWh changes with the season, how fast the car is going, whether the car is on level ground, going up, or going down, how bad the traffic is, the wind, use of cabin heating/cooling ... and more. LeafSpy lets you set the presumed miles/kWh; the car decides on its own mostly based on recent driving.

Each approach is correct some of the time, often wrong, and almost always in disagreement with one other. With experience a lot of EV drivers just note the energy remaining, and depending on what driving they are doing for the remainder of the trip, mentally plug in a reasonable miles/kWh.

E.g., I live about 1,000 feet higher elevation than most of my driving into our city and then back home. After I drive into town the car is confident that each kWh of energy will be good for 10 miles, but that is because it doesn't know I'm going home now -- uphill.
But I know from experience that my drive home is at about 400 Wh/mile (0.4 kWh/mile), and since the drive is 10 miles, I better have the better part of 5 kWh remaining or plan to stop along the way.
 
dmacarthur said:
Leaf Spy Pro... has some confusing options (scrolls thru various different parameters) but one of them allows you to input info and predicts a range. I don't use it but it is there.
Click to expand...
The "confusing" options are actually different ways to calculate the remaining range and are discussed in the manual. The T is the estimate based on the current trip (your average consumption since you started the car). The C is the estimate based on your average consumption since your last charge. I is the estimate based on the last mile/km driven and thus fluctuates the most just like the indicator on the Leaf's own screen. Last, is the "calculate" option based on whatever value you choose to enter. There is also 2 ways for the range estimate to be calculated, one a simple equation and the other an algorithm that includes outdoor air temperature and some other factors I do not recall.
Click to expand...
 
Vandervecken said:
... Is it normal that the real efficiency is around 3, even though the official value is 4? ...
Click to expand...

3 Does seem a bit low but it all depends on conditions. I average about 3.7 when I'm not being particularly careful. Some folks, God bless 'em, manage to average 5 or over. There are various tips and tricks to get more efficiency from your LEAF:
https://www.mynissanleaf.com/viewtopic.php?p=127651
 
The biggest variable in range is the speed. Highway driving gives you much higher wind resistance and a shorter range. We are used to seeing higher mpg for ICE cars. The ICE engine is very inefficient at low power and low speed. Not so for electrics.

With my 42 kwh battery I figure 120 miles on the highway or 150 otherwise.
 
Thanks for the ideas folks. I recently increased my tire pressure and I have seen an increase in efficiency. Currently sitting around 3.5, which is an improvement from 3, especially considering that we're in a cold climate right now (35-40 degrees F).

Cheers!
 
Vandervecken said:
Thanks for the ideas folks. I recently increased my tire pressure and I have seen an increase in efficiency. Currently sitting around 3.5, which is an improvement from 3, especially considering that we're in a cold climate right now (35-40 degrees F).

Cheers!
Click to expand...

If your driving speeds are under 50 mph (80 kph), then tire pressure will have a bigger effect on the efficiency. Especially if you are using LRR tires vs. just regular tires. Once you get over those speeds, the tires and the tire pressure (within reason, you are not running them flat) start to get canceled out by the wind resistance. So, as an example, if all your driving was at high speed, then cheap tires at proper tire pressure would work just as well as more expensive LRR tires because both of them are fighting wind resistance all the time. If more of your driving is around town and cities where speeds are often lower, then the type of tire and the air pressure will make a really big difference in range as the wind is no longer the issue, it's the friction between the tires and the road.
As for your question, 4 miles/kWh is what Nissan uses to gauge kind of a standard range to work with the GOM. But as you can already read from the previous comments, you can go much higher, all the way up to 5 m/kWh with LRR tires, higher tire pressure, lower speed driving, more conservative climate control settings, etc. Hitting right around 3 m/kWh is about the same as driving at maximum speed in the Leaf on a good day where the wind resistance is eating all the power at 90 to 100mph (144 to 160kph) instead. ;)
 
If your driving speeds are under 50 mph (80 kph), then tire pressure will have a bigger effect on the efficiency. Especially if you are using LRR tires vs. just regular tires. Once you get over those speeds, the tires and the tire pressure (within reason, you are not running them flat) start to get canceled out by the wind resistance. So, as an example, if all your driving was at high speed, then cheap tires at proper tire pressure would work just as well as more expensive LRR tires because both of them are fighting wind resistance all the time. If more of your driving is around town and cities where speeds are often lower, then the type of tire and the air pressure will make a really big difference in range as the wind is no longer the issue, it's the friction between the tires and the road.
Click to expand...

I'm sorry, but it appears to me that tire resistance and wind resistance add together, rather than canceling out, even in part. For that reason, adequately high tire pressure matters as much on highways as on city streets.
 
LeftieBiker said:
I'm sorry, but it appears to me that tire resistance and wind resistance add together, rather than canceling out, even in part. For that reason, adequately high tire pressure matters as much on highways as on city streets.
Click to expand...

You are right, I phrased it badly. The two don't cancel each out out, one just gives way to the other.
Air resistance is proportionally squared to speed. At low speeds, the air resistance is low. The tire resistance is greatest at 0 speed and decreases the faster you move. Once you get the vehicle moving, tire resistance drops off pretty fast and wind resistance starts to take over as the force the Leaf is pushing against and thus using more power.

Low speed driving, the tires can be tweaked for more range. High speed driving, you are at the mercy of wind resistance and properly inflated tires. :)
 
knightmb said:
LeftieBiker said:
I'm sorry, but it appears to me that tire resistance and wind resistance add together, rather than canceling out, even in part. For that reason, adequately high tire pressure matters as much on highways as on city streets.
Click to expand...

You are right, I phrased it badly. The two don't cancel each out out, one just gives way to the other.
Air resistance is proportionally squared to speed. At low speeds, the air resistance is low. The tire resistance is greatest at 0 speed and decreases the faster you move. Once you get the vehicle moving, tire resistance drops off pretty fast and wind resistance starts to take over as the force the Leaf is pushing against and thus using more power.

Low speed driving, the tires can be tweaked for more range. High speed driving, you are at the mercy of wind resistance and properly inflated tires. :)
Click to expand...

I might understand what you mean, but the way you phrase it reads wrong.
Tire rolling resistance does not decrease with higher speeds, but the weighted *contribution* to total resistance from tire rolling resistance decreases as speed increases.

An example might help here:
Tyre RR is say 18 Wh/Km. It stays about the same at the speeds we travel
Say air resistance is 30 Wh/Km at low speed, and 150 Wh/Km at highway speed

Then total resistance at low speed is 48 Wh/kim
and 168 Wh/Km at highway speed

LRR that reduces RR by 20 would drop low speed driving to (14.4+30) = 44.4 Wh/Km, or about a 10% improvement
On the highway total resistance would be (14.4+150) = 164.4, a 2% improvement
 

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