Nissan LEAF electric motor and transmission

by Ernie Hernandez on November 1, 2010

Nissan LEAF motor assembly

So… how does a LEAF work?

[UPDATE] This article was written in 2010 and applies to the 2011 and 2012 models of the Nissan LEAF. A different electric motor is used on the 2013 and later models with slightly revised specifications.

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We’re not really going to tell you how a LEAF works. But… we will give you a little insight into how the LEAF is different from the car that you are currently driving.

Recently, the good folks in Nissan’s European Newsroom provided us with some additional technical specifications for the LEAF that had not been previously released. For instance, we now know that the AC synchronous motor can turn a maximum of 10,390 revolutions per minute (RPM). We heard from some other sources as much as 18,000 RPM, but thought that might be on the high side. And most likely, you have heard by now that LEAF does not use a conventional automatic or manual transmission. It uses a single speed reduction gear with a final drive ratio of 7.9377. So what good does that do anyone? Good question. Divide 10,390 by 7.9377. Go ahead… we’ll wait. Come up with 1308.94? Good! So did we.

1308.94 is how fast the tires will rotate when the motor is turning the maximum 10,390 RPM. Why is this important? Because, since we know that the tires are a Bridgestone Ecopia model, size 205/55R16, we know that the tires have a diameter of 24.9″ and will turn 837 revolutions per mile (not per minute). With these givens, at 60 miles per hour these tires will turn 837 RPM. But if the electric motor is turning 10,390 RPM, and the tires are turning at 1308.94 RPM, how fast are we going? Simple… do the math!

1308.94 RPM divided by 837 RPM equals 1.56. So at maximum motor RPM, we are traveling at 1.56 times 60 MPH, or 93.8 MPH. We think that we recall reading that the fastest the LEAF has traveled (at least in road tests that we have seen) has been 94 MPH or 95 MPH, so these calculations are probably fairly accurate. Here at Living LEAF we’re car geeks… what can we say?

Some other numbers released: curb weight 1,525kg (3,355 pounds) minimum 1,595kg (3,509 pounds) maximum. These are based on some European spec that we are not familiar with, but we expect US numbers to be similar. The variance is likely due to the trim level and associated equipment differences.

One other little bit that we picked up – both front and rear brake rotors are ventilated. Typical practice on compact cars is to provide vented front rotors and solid rear rotors. Venting the brakes at both ends of the car offers several advantages – cooler brake operation, longer component life, improved performance, along with potentially less maintenance. This is the type of treatment typically found on more expensive performance oriented vehicles. Nice to see on the LEAF.

{ 35 comments… read them below or add one }

Neil Bettenhausen February 7, 2011 at 6:56 am

Very interesting. Thanks for posting. Now I can tell my friend who drives a Hummer that my car rev’s up much higher than his! And….I can start out in “high” gear, without shifting.

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Ernie Hernandez (LEAFguy) February 7, 2011 at 8:40 pm

Isn’t it amazing what knowing a few facts can do?! 🙂

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Tim July 18, 2011 at 3:39 pm

Excellent Information.. This Clears up many Forum Battles! I am excited to see these Babies rolling around Canada, and Charge Stations Emerging.. Keep them coming Nissan, You are Top Notch for bringing these out!!

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Ernie Hernandez (LEAFguy) July 20, 2011 at 5:54 pm

Tim – welcome to Living LEAF. Hopefully, you will continue to find our site of service. My whole goal is to get good info out in the world about the LEAF and EVs in order to help encourage their adoption.

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Eric September 4, 2011 at 7:12 pm

Still a weak autonomy though.I’ll buy an electric car when the 500 Km autonomy range will be a reality.

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Ernie Hernandez (LEAFguy) September 5, 2011 at 8:54 pm

Eric, welcome to Living LEAF. Nissan’s LEAF is not an everyman car – yet. This is what will make cars such as the plug-in Prius hybrid and Chevy Volt more attractive to those interested in going electric, but needing a greater range than that currently offered by the LEAF. We likely will not see 300 mile range anytime soon from any pure battery electric vehicles carrying a LEAF price tag. If you do wish to go full electric and wish to achieve that range, you can look into the Tesla Model S sedan. The Model S is slated to be available next year and will offer the 300 mile range that you seek. Tesla’s first vehicles produced will be the top of the line Signature model, which will require a premium over the standard $70,000 300 mile model. Pricing has not yet been announced for the Signature model.

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jeff b September 18, 2011 at 9:12 pm

Test drove a leaf this weekend. Its peppy and cute. But small and with very limited range. Not the sort of car that most americans would consider spending over $20,000 on. The lack of gas is great but, I only was projected to have an 87 mile range by the car (not in economy mode, driving normally, without hypermiling sort of tricks). 87 mile range is just too limiting to make this useful as a viable transportation option, unless its only a “spare” car for local errands. After seeing how small the battery pack is in the traveling demonstration currently on tour, it seems that nissan could’ve doubled up on the cells; and gave america a 200 mile range vehicle that would be a truly reasonable choice (if done with a price of around $30,000). Anyways…it seems to me that the first manufacturer to produce THAT vehicle is the one who will be the “winner”, i.e. the first one to have a practical ev that americans will start purchasing in mass. Still, we needed to start down the road to electric cars somewhere, and nissan is to be congratulated for being the first horse out of the gate. I hope the race is run well.

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Ernie Hernandez (LEAFguy) September 19, 2011 at 10:33 pm

jeff – we replied to your comment in another post regarding many of the topics you raised here. You say that if Nissan could have created an EV that went 200 miles for $30,000 they would have a winner. The fact of the matter is, no one can produce that car currently. Not Nissan, GM, Tesla, or any of the other manufacturers coming out with electric vehicles in the next few years. Five to ten years from now? We’ll see.

As you say, “we needed to start down the road to electric cars somewhere…” Nissan has done exactly that.

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Justin H January 9, 2013 at 11:55 am

+1 to that Ernie. Even though the car cant make it around the globe in one charge, the fact this car is ground breaking technology. Its comfortable, can take the family around town and highly economical…there is nothing bad you can say about the car…well maybe the looks, but a fugly car is still cool to drive and I Do enjoy it.

Nissan started, hopefully they keep up with the technology and advancements while others (like VW Now looking to do a full EV Golf) might leave NISSAN in the dust.

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Varun Bhatia January 3, 2012 at 10:39 pm

Hey,
I am Officially the First Leaf owner in New york. i currently live in New hyde park and because i couldn’t wait to order one i purchased one from Portland and it will be shipping in 2 to 3 days finally waited over 13 days for delivery due to xmas and new years. Well my point is i plan on driving my leaf atleast 40 miles a day and up to 70 miles a day. I live in the border of queens and long island. My location is optimal for the range of the leaf. I am 24 miles from manhatten and 24 miles from most parts of Long island like the school i plan on going to SunyFarming dale and then NYIT which currently has a EV Solar charging station. I will keep everyone updated on my range and i have a gas car for when i am low on batt. I can just leave the leaf at home and pick up my ice for further driving. I often go past my house to go from long island to queens and visa versa. For example i go to car meets in Long island but i drop my mom to work very often in Astoria, Queens. so depending on where i go first i can stop by my house to switch cars. My current ICE vehicles a 1996 miata 22mpg but only 87 octane. I also own a 2003 maxima with 187,000 miles on it with about 16 mpg on 93 octane. I bought the car New and have driven it from 2004 to the present yes that is why i bought a leaf. even if i cut my miles to half i save about 200 to 250 dollars a month in gas making my leaf $320 per month instead of the 520 i pay post tax rebate. So I feel if the leaf is your second car there is plenty of room for a leaf as your second car. I can even charge it at School as they will be happy to help, this will extend my leaf driving even further. My final plan is to get a Range extender trailer which i can use to say go to Florida or Canda in the car as opposed to taking my Maxima. then i will get about 35 MPG on an the worst setup and that’s not too bad for once in a while and still better MPG then most cars out today. ok well sorry for the long post if you have read this much then i hope you guys will read my updates on how well the LEAF experiment is doing in my household.

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Ernie Hernandez (LEAFguy) January 4, 2012 at 10:09 am

Varun – Welcome to Living LEAF. We are pleased to hear about your experience, as it will help others that may be in a similar situation. We would love to hear from you with additional comments as you experience your new LEAF. Congratulations!

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Gadge January 17, 2012 at 5:14 am

My calculations, however, show that the circumference for that tire size is 78.16 inches divided into a 63,360 inches/mile yielding 811 revolutions which gives a factor of 1.61 with a theoretical top speed of 97MPH.
There’s therefore a discrepancy between your posted numbers and mine…could you show the details of your calculations.
Thanks

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Ernie Hernandez (LEAFguy) January 17, 2012 at 11:50 am

Gadge – welcome to Living LEAF. All of my calculations are included in the article.The difference between our top speed is the revolutions per mile. I used 837 (as indicated in the link to Tirerack.com (Tire Rack tire size info)). You used 811 based on circumference. There’s the difference. Using your circumference number results in a top speed of 96.8 vs. my calculated 93.8. But when it really comes down to it, does it matter to the majority of LEAF owners how fast their car can go? In daily driving, most will rarely, if ever, exceed 80 miles per hour. In over 6 months we have not yet personally explored the top speed of our LEAF. Perhaps we’ll put that on our agenda. Thanks for the idea!
.

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Gadge January 19, 2012 at 8:02 am

Ernie,
I found the reason for the discrepancy. When tire manufacturers report ‘revolutions per mile’ in the specs, depending on the tire, a 3-5% ‘slippage factor’ is applied. In this case adding 3.2% to my calculated 811 RPM yeilds 837 as reported for the Bridgestone Ecopia which is a more energy efficient ‘low resistance to roll’ tire.

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Ernie Hernandez (LEAFguy) January 19, 2012 at 9:51 pm

That makes sense. I figured there was some reason for the difference, but I wasn’t quite sure why. Now we both have the answer. Thanks for checking it out.

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Jonathan November 12, 2012 at 7:13 pm

How does the leaf deal with turning and wheel rotation speeds? Other cars use things like a limited slip differential (http://en.wikipedia.org/wiki/Limited-slip_differential). Presumably the leaf must solve this problem (unless it delivers all power through a single wheel).

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Ernie Hernandez (LEAFguy) November 12, 2012 at 8:42 pm

Hi Jonathan – Welcome to Living LEAF. You are almost right. While some performance cars (think Mustang, Camaro or 370Z) use a limited slip differential to help put the power to the ground instead of just spinning your wheels, most cars (including the LEAF) use a regular open (or non-limited slip) differential (wiki article found here). The difference is that with an open differential, its primary job is to allow one tire to rotate faster than the other to corner smoothly and not break anything. A limited slip differential will sense the spinning wheel in a high powered car if excess power is applied too quickly and literally limit slip of the spinning wheel and send that power to the wheel that has traction. Here’s a great page of articles on the How Stuff Works website (found here) that explain how they work. I hope that helps.

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Elroy February 9, 2013 at 5:32 pm

I instrumented my 2012 LEAF with a racelogic GPS unit (Very Accurate).
91.7mph maximum speed.

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Ernie Hernandez (LEAFguy) February 9, 2013 at 6:49 pm

Elroy – Welcome to Living LEAF. And thanks for the feedback!

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Laurie September 19, 2014 at 9:06 am

For those of you with “range anxiety” – Note that most people do not drive more than 30-50 miles in a day. The LEAF is perfect for running errands, getting your kids to school, short commutes, etc. Or, even if your commute is a little longer, you might be able to charge up at work or nearby. The benefits of the LEAF are endless, starting with the most important: ZERO emissions. No burning of fossil fuel. If you live in Seattle like we do, the extra benefit is that the electricity we use is clean energy. Or you can set up a solar panel just for charging your car. Instead of paying $100 – $125 per month per gas, we pay about $25 or $30 per month for electricity. No oil changes, no trips to the gas station, and hardly any moving parts to maintain – no fuel injection system, carburetor, etc. No oil dripping in your carport or on the roads. No obnoxious fumes. no idling. quiet, smooth, gliding ride.

If the range anxiety is too much for you, consider the LEAF as a second car. you will soon find that you think of it as your FIRST car. It is so much nicer to drive than an ICE (internal combustion engine).

And did I mention – no emissions? We are destroying life on earth as we know it by burning fossil fuels – this is one step you can personally take in the other direction. Its worth a bit of inconvenience.

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Ernie Hernandez September 19, 2014 at 9:12 am

Laurie – Welcome to Living LEAF. And thank you for your comment. As your personal experience shows, the fuel cost savings is significant when one moves from gasoline to electricity. A savings of 60 percent to 70 percent is not uncommon due to the efficiency of an electric motor over a gasoline engine and the lower cost of electricity compared to gasoline. Also, some individuals are fortunate enough to work at a company like Qualcomm, Google, or many others, that offer employees the ability to charge their LEAF at work. My wife loves the fact that she doesn’t have to go to the gas station anymore also. Thanks again.

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joseph November 17, 2014 at 7:16 am

As for the range anxiety I lost that the day I picked up my leaf from the dealer which was 60+ miles from my house. My commute round trip is 40 miles which leaves me the ability to run errands after work it wonderful not needed to go to gas stations except once a month to gas up my long distance toyota echo which is now the secondary car. Well i would say more but I have to go to work in my leaf.

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John Loveless January 23, 2015 at 11:29 am

Thanks for the great information about the top speed of the Leaf and why.
I was surprised that the top speed was only 95 mph. I have gotten our 2013 Leaf up to 94 quite easily. Of course that was based on its own speedometer and seems to be off 2 mph. I keep the tire pressure on the high side at 44 psi so perhaps that is increasing the diameter (and circumference) a bit and helping bump up the top speed.
I don’t plan on going that fast much anyway because of how badly it kills the mileage. Energy to overcome air friction increases by the cube of the speed after-all.

Thanks again.
John

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Ernie Hernandez January 23, 2015 at 4:51 pm

John, welcome to Living LEAF. Any vehicle speedometer will be off at high speeds. They are generally calibrated to be most accurate at typical highway speeds.

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Gerald March 16, 2015 at 10:56 am

Does my 2015 Leaf have a variable type transmission complete with belts?

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Ernie Hernandez March 16, 2015 at 5:51 pm

Hi Gerald – Welcome to Living LEAF. All LEAFs, from 2011 through 2015, use what’s called a single speed reduction gear which is essentially a one-speed transmission. The LEAF is either in gear, or it’s not. What you described is called a Continuously Variable Transmission, and Nissan has been a leader of that particular technology, having used it since the introduction of the 2003 Murano in the United States. Nissan has used it elsewhere since the early ’90s. Since the electric motor revs to over 10,000 rpm, there needs to be only one gear which is adequate to take the LEAF from zero to over 90 miles per hour. This is why you feel no shifting and no hesitation upon acceleration. I hope that answered your question.

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EV Convert May 1, 2015 at 12:17 am

At age 67, and Leaf owner of 3 months, this is my 26th car in my lifetime, and by FAR my favorite so far! Plug it in at night and go during the day. I still have a NGV for longer trips, but in 3 months have put 3000 miles on the Leaf, and 250 on my NGV. Yes, it has to add to my electric bill, but actually no increase from same months last year? Maybe going Leaf green influenced our home power use habits? Used the Nissan, and Chev dealership (free) quick charge a few times–easy-peasy–walk across street for lunch or dinner–good to go! Service Schedule is great reading–inspect, rotate tires, change cabin filter. After down payment leased for $225 per month. Small issue, but HVAC is batt draw–and I hate the backup-beeps (of course I would never disable–oops, it just magically stopped working). Rides like a skateboard, but I knew it was not a Cadillac, and for short trips–works for me.

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Ernie Hernandez May 1, 2015 at 9:49 am

EV Convert – Welcome to Living LEAF. Thank you so much for your contribution to the discussion. Through our experiences hopefully others will find that an EV is not only viable, but a preference for them.

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Ken Arock July 26, 2015 at 4:57 pm

Hi Ernie,’
I hear that the gear ratio of the gear box is 8:1, I found for that tire size is will rotated 811.1 rev/mile, if the speed 60 mile/hr then the motor speed is 8X60X811.1/60min= 6488.8 RPM.

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Ernie Hernandez July 26, 2015 at 5:26 pm

Ken – Welcome to Living LEAF. As indicated in the article, the final drive is 7.9377 to one. Pretty close to 8:1.

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jondoe88 September 23, 2015 at 8:29 pm

We’ve had our Leaf for a whole week! My wife loves it! And I’ve finally come around to its shape.
We bought it in Alabama, and had a 140mi drive back home. What pioneers! We stopped at every Nissan dealer between their and Atlanta. (two, 30min, each stop. An L2, and an L3). Everything worked out, and we made it home with 20 miles left. (there are many dozens of charging stations in the Metro area. But if the final stop wasn’t available – we would have had to find a slow-charge, and come back for the car the next day).
My wife has a 25 mile round trip to work. We will have to charge it Sunday night, and Wednesday, for work. And for the weekend, Friday night, and maybe Saturday, depending on how much driving we do. This is an excellent city car. And 2nd car.
I drive the car like a regular car. 65-70 on the interstate. (OK, I’d be doing 80, with traffic, in the other car….)

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Ernie Hernandez September 24, 2015 at 9:28 pm

jondoe88 – Welcome to Living LEAF. Thanks for your feedback on your first week in the car. Others will find it helpful. You might find it useful to plug in every night, just to cover any unexpected driving needs. After all, it takes just a few seconds to plug in and then unplug it in the morning. Welcome to the world of electric car ownership.

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Tahrey May 12, 2016 at 7:07 am

Ah, never knew about the tyre slippage thing. When I ran the numbers myself I thought maybe whoever had calculated 837rpm had used a value of Pi equal to 3.04 instead of 3.14 or something 🙂

I went right back to first principles with the stated size and rounded to a good 5sf instead of 3sf (and stayed metric all the way through, after converting the rim size to mm), and got a theoretical figure of 809.9 revs/mile, with about a half percent variation up and down if we assume that the profile height is absolutely true when the tread is about halfway worn (5mm, with new = about 8mm and borderline illegal = 2mm). Obviously 837 vs ~810 is a good 3.3%… which allowing for some rounding error is equal to the quoted 3.2% slippage.

If you assume *zero* slippage, then it looks like, at least in terms of making it accurate at the driveshaft speed level, Nissan went for a very round-number approach; 150 km/h with the specified 1985mm rolling circumference tyres and the 7.9377 gearing comes out at bang on 9990 rpm. Or in other words, trying to achieve that particular milestone top speed (1.5x the Japanese national limit, btw) whilst JUST keeping the motor under 10,000rpm. If it then happens to have an absolute safe sustained speed of just under 10400rpm, then that’s a 4% (and exactly 400rpm) headroom, just about covering both the tyre wear and slippage – and meaning an absolute theoretical maximum speed of 156km/h or 97mph. Which I think covers all the variation we’ve seen reported (from a lower maximum of 91.7mph – or 147.5km/h – to about 95mph – 153km/h).

Nissan of course can’t really predict how slippy any tyre the owners may install will be, or the roads they drive on, or how chunky the tread, or indeed if they may not be able to get hold of (or afford, or like) the exact specified size and so fit something with a slightly larger rolling circumference… and may get in trouble if the speedometer under-reads and causes an accident or a prosecution… so they are sort of obligated, even with modern super-accurate digital speed recording and readout, to assume no slip at all (which causes up to 5% over-reading, or maybe just 3%) and maximum typical tread depth (another 1% or so), and then to build in at least an extra 1 or 2% (so that there is, say, an extra 1mph safety margin around 50mph, or at least 1km/h at 100k) just in case of any other unpredictable factors.

150k x 1.01 ~ 1.02 = 151.5 ~ 153.0 km/h, or 94.1 to 95.1 mph… Which is maybe what it’ll say when the driveshaft speed is equal to 150km/h with no slip. Take off 3.2% and that could be as little as 145.2 km/h… or 90.2mph. At the extreme, 89.51mph (or juuust over 144km/h) would be a 4.1% downward variance from the intended road speed – or in other words, it might be what an accurate GPS would indicate when the speedo is showing 94 or 95mph, and the shafts are doing a theoretical 150.0k – with quite well-worn tyres that are a month or so from needing to be replaced (and have all worn at an even rate with none of them due for renewal before the others have worn as much!) and the stated LRR tyre slippage.

So it’s still a “90mph class” car, if you round off to the nearest mph, even though the road speed is more than 4% below the theoretical ideal, and the speedometer might be overreading by more than 6%…

Down a big hill, you might be able to push it far enough to nudge that motor maximum (presumably the power ebbs off to zero between 9990 and 10390 – or indeed 10400, as even an unloaded motor requires a little power in order to keep turning – and then aggressively applies more and more braking / reverse thrust up to the full 107hp as it approaches 10500rpm, which may be the actual breakdown speed…) – which would be a driveshaft speed of ~97mph, a real road speed of maybe 150km/h at last, and a maxed out speedometer reading of 99mph 🙂 (or 159~160km/h…)

And thus it can cover you for legal driving in basically any current posted speed limit in the world (highest I know of are 85mph in – or at least proposed for – Texas, 140km/h in Poland and… Dubai? … and 150km/h *somewhere* I can’t exactly remember, which may also have been merely a proposal) with just a little in reserve if needed for some reason … or if you’re out on the Autobahn 😀
(Not much good for pushing the 160k limit Austria briefly flirted with, but the hills would probably be your bigger challenge there anyway, as well as people in other vehicles that are having keeping up even whatever speed you’re setting as their power:weight ratio is even lower than the Leaf’s somewhat misleadingly low 69hp/tonne, and they’re not thrashing their engines at the redline anyway… plus who’s going to be too mad that you’re putting down a good 145k / indicated 155k in a 160, so long as you pull out of the way as soon as is safe and practical?)

So it all works out quite neatly really, despite looking a bit puzzling to start with.

Clever chaps, these Japanese.

(I also did some mathing with the power and torque vs normal cars, but I’ve got something I need to go do AFK first, so there now follows a natural breakpoint.)

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Tahrey May 12, 2016 at 10:52 am

As for the torque and power figures, as people often get themselves in a tizz about them and don’t really understand how they relate to real-world performance (including such shiners as suggesting an EV would go quicker if you added a gearbox to keep the motor rpm in the middle of the max torque region, and thus way below the max power…) :

We need to relate it to the weight, and to the gearing. For this I’ll compare to a couple of particular other vehicle models, Nissan’s own Micra (as I happen to own one ;), with a choice of two very modern engines – both 1200cc, one naturally aspirated (81 lbft @ 4000rpm, 80hp @ 6000rpm), the other lightly supercharged (108 lbft @ 4400rpm, 98hp @ 5600rpm) – and an old VW Polo (again, something I owned; 1043cc, 55 lbft @ 2800, 45hp @ 5200, plus a few other engines generally with about the same specific output but varying in capacity and some with slightly altered torque vs power biases) with a fairly stoneage engine that can act as a base for larger, lower tune lumps running on poorer fuel. These are both somewhat lighter (995kg for the Micra, 850kg for the Polo, vs about 1550kg for the Leaf), moderately or decidedly low geared, and a little smaller, which is maybe unfair, but it just happens to be what I was directly comparing to whilst messing around with the figures. You can take the results and multiply by your own comparison car’s weight (and gearing) to get similar outcomes.

Particularly, the high torque can be deceptive, thanks to the fixed gearing (ICEs use their gears to multiply otherwise lower torque figures) and the power output is affected in one direction by the heavier vehicle weight but also in the other by being more or less completely constant, which is something only otherwise seen in CVTs, hybrids with IVTs, and some deliberately de-rated engines (which tend to have very flat, wide power plateaus) like base model turbodiesels if paired with very smooth-shifting traditional automatics.

So, we have a 1550kg vehicle, with 107hp available from more or less the top of the basically flat peak torque band (which goes down very nearly to 0 rpm), thanks to the main thing governing both of those figures being not their electromagnetic characteristics or the flamefront physics of hydrocarbon combustion, but how much voltage the battery and controller can provide (and the motor withstand) along with how much force the shafts and transmission can cope with, in the case of torque, along with how much current (and thus total power, at max volts) the system can flow for the remainder. There’s a slight tail-off towards max speed due to internal motor friction, but for all intents and purposes the torque graph is a straight line followed by a parabolic fall-off, and the power graph is a straight diagonal line from the origin to the crossover point, and a flat line after that. The max torque is 207 lbft in the original and 187 lbft in the retuned version (still enough to squirrel the tyres), so that max power crossover point is reached at ~2700 and ~3000 rpm respectively. The single fixed gear is within less than 1/10th of a percent of 15km/h per 1000rpm (at least theoretically, not counting slippage etc), so we may as well use that – IE those motor RPM work out to road speeds of 40.5 and 45 km/h, or about 25 and 28mph, roughly where peak power would come in with a typical gasoline ICE in 1st gear.

The gearing, however, is more like that of a medium-long 2nd gear – 9.32 mph/1000, fairly close to the Micra’s 2nd – and is only that high because of the large wheels, the actual reduction being more like that usually seen in a medium-short 2nd gear; indeed, the total drive ratio is quite close to that of the Polo’s actual 2nd – 1.958 for the gear itself, and a 4.063 differential. This does mean that the effective torque is rather reduced vs that of a conventional car of similar spec, at least whilst starting off. Obviously, 207 lbft being brought to bear in 2nd gear still isn’t anything to sniff at (I would happily start in 2nd all day long in my old TDi with about 150lbft), but it does reduce the Wheel Torque bragging rights vs a normal car.

To whit: something otherwise setup with a 2nd gearing matching the Leaf’s fixed reduction, but having a 1st-2nd gap similar to my model vehicles (about 1.8x, varying around 1.75 to 1.85 depending on model), would only need a maximum thrust of 104-115 lbft at the crank to match it at the wheels. At least, matching it during the small window where that maximum is available…

We can already see that the lower torque model is comparable at the wheels to the supercharged Micra, for a small window, though once the Leaf gets into the mid 20s mph the ICE is outgunned and never has a chance to regain the upper hand. To actually have a fighting chance, we’d have to bore it out a bit … though only to about 1300cc. (Nissan’s likely choice for a car of the Leaf’s size would be their 1500cc version of the same engines…). The naturally aspirated, modern engine would need a capacity of about 1.6 to 1.8 litres, and the more primitive one somewhere around 2.1 to 2.5 litres depending on exact tuning bias.

So whatever 2.5 litre V6 they’re comparing it to, it’s nothing to write home about, as it’s at the lower end of the specific output envelope even for a quarter century ago…

But, we also need to add a correction factor for the weight, as this thing is more than a tonne and a half (and the heaviest thing I’ve yet owned, which coincidentally enough had a 106hp engine, was under 1.2 tonnes). Comparing it to the Micra, we can basically just divide by 1.55 … to put the Leaf on an equal power to weight basis, we’d have to detune whichever engine was in the city car… to just 69hp. Oh dear. There were a whole raft of rival cars I struck off my list when I was shopping this time round because I didn’t want anything under 70hp (and 70hp per tonne, additionally), or 75 if I could help it, because they would just be too slow – a decade and a half of driving experience has show this is about what you need for comfortable performance (as opposed to “challenging” below it, or “entertaining” above it). Thus 0.995 tonnes with 80hp was bang on.

Comparing it to the Polo, that falls to a mere 59hp, which is about the lowest power engine VW currently installs in any of its main market cars. The equivalent capacities from the least efficient to most efficient tech level here come out around 845, 1035 and 1367cc… not the biggest ever.

Torque-wise, we’re looking at 120-134 lbft for that notional second gear – so a little larger than the engines conceived of above, so still perfectly decent in that small wedge where you could consider it more the 2nd gear torque zone than 1st – but for first, it’s a rather more lacklustre 67 to 74 lbft, again being embarrassed in the starting-oomph stakes by the punchier ICEs (equivalent capacities of 744 thru 1096cc); recalculating for the VW, it’s 102-114 lbft for 2nd (so, still needing a roughly 2L lump to provide it at that S.O.), but just 57 to 63 for first, topping out at an equivalent of 1199cc even with that primitive motor.

Which, all in all, is pretty strange. The Leaf’s all-up real-world performance is on a par with, and actually slightly better than, the supercharged Micra. So how the heck does it manage it, when the effective gearing from 0 to 100km/h is more or less equivalent to having that larger engine but starting and staying in 2nd, and it’s got such a relatively heavy body to drag along? The power:weight, torque:gearing and wheel-torque:weight figures and theory are rather in conflict with the observed acceleration. That old Polo, after all, took about twice as long to reach 100km/h, and increasing the engine size by about 15% isn’t going to suddenly make it stay neck-and-neck. On the whole, the Leaf’s speed (not counting the governor) would be more suggestive of a conventional-drive and conventional-weight car in the same size class with a fairly decent 1.6L or mediocre 1.8L engine instead.

I can only presume the secret is in how it sustains those outputs in such a rock solid way. The raw, peak-point figures can be very deceptive when the shape of the dyno graphs are so divergent. The ICEs have rather peaky graphs (the Micra on the power side, with quite flat torque, and the Polo on the torque side with surprisingly flat power output), and limited rev ranges, so you have to slam up through what can be annoyingly widely spaced gears in order to try and keep them both on the boil and in one piece rather than decorating the landscape – and abuse the clutch in order to get a good start, as you won’t get particularly strong torque below about 10mph otherwise. The torque and power at the wheels therefore is pretty sinusoidal and stepped at the same time, with an occasional complete zero-out, and the potential maximum not being exerted for more than a small percentage of the entire process.

Whereas the electric car applies maximum torque to the drivetrain within a split second of the pedal being floored, keeps it applied (or at least as much as the traction control meters out) to about 25mph, then backs it off gradually and smoothly in order to keep the power output steady at the maximum allowed. No temporary peaks. No up and downs, no steps, no dropouts, just that otherwise unexciting figure, being applied in a non-stop way. Across the whole acceleration from rest to highway speed, your ICE might be lucky to claim an average output of 75% of its maximum potential (and even if it has a CVT, that’s unlikely to be over 85-90% because of the extra transmission drag they represent despite the stepless ratio change), whereas the electric has 100% all the way.

So the quoted figures, after the above serial dividing-down, can then be multiplied by probably 1.3x or more… so, a good 1.6 litres or so even for that small equivalent VW engine we arrived at. Suddenly everything makes sense again…

Weird how numbers can play tricks on you, isn’t it. Don’t let the games manufacturers play with them lead you astray… 🙂

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Ernie Hernandez May 20, 2016 at 2:09 pm

Tahrey – Welcome to Living LEAF. Sorry about the delay in approving your comments. It’s clear that you’ve spent some time looking at these issues. Thanks for your contribution to the conversation.

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