Nice Efficiency Improvement

HerdingElectrons said:

Just adding a bit of info concerning the OEM wheel weight of the 2018 SL 17" wheel. The stock wheel weighs 25.2 pounds.

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The stock 17" alloy on the 2018 SL weights 47.2 lbs mounted with brand new 215/50 17" 95XL Bridgestone Ecopia 422 Plus. I have a set in my shop waiting to go on the car so I checked one with a digital scale. They are noticeably light for their size relative to our other cars.

These tires weigh 21.4 lbs, so my rim should be in the 25.8 lb range as Herding has posted. TPMS and balancing weights likely make up the difference.

Any reduction in rotating mass will make a difference on acceleration (like a lightened flywheel) but keep in mind that your tires will still be the same mass, and the effective gain found by decreasing rotation mass will decrease as you get closer to the hub. If you visualise where the mass is distributed in the rim vs the energy required to accelerate the mass, it makes sense. You should see at least a small improvement in acceleration, and if your driving is urban, you may also see a small increase in efficiency. On the other side, regeneration may actually be reduced a bit as it will be a bit easier to overcome the lighter rim/tire's rotational inertia.

You should do a few rolling tests (same stretch of road) and time 30-60 runs before and after...post up your results

On my autocross car, I can very much measure the difference on different rims/tires with respect to acceleration, particularly when the rim is a different size. This article measures an 8lb or so weight saving per wheel as a an increase of 0.4 seconds or so on the 0-60 times with a Miata (much lighter car): https://grassrootsmotorsports.com/articles/are-lighter-wheels-really-better/
The article also makes a very good point on how reducing rotating mass vs just making a car lighter to the car is quite different. Their results are consistent with my own observations, particularly "in gear" acceleration on the highway with a lighter rim/tire combination where grip and wheel spin are variables you can mitigate (vs the 0-60 runs). That's why I'm suggesting you just measure 30-60 times.

My thoughts on test cycle were to have my 2 leafs drive the same loop twice at the same time with each car leading during one of the laps (total of 35-40miles mainly highway around 60mph). I have done somethimg similar in an earlier test and the S+ is about 10% more efficient than the SV+. Measure the relative difference in efficiency between the cars.

Than replace the S+ tires with the EV01s+same tires.

Repeat test to see if difference between cars has shifted at all. The hope is to see a small increase in difference between the cars. By running the both at the same time in both tests, you reduce a lot of the variations due to traffic, absolute speed, small distance differences, weather, etc. The relative difference is more important than the absolute as there are too many uncontrollable variables if not on a test track.

Ideally we would do both the before and after test 3 or 4 times, but the wife and kids are not nearly as excited to spend hours testing as I am.

Let me make a prediction here after a close look at the Tesla 3 aero covers, and the LEAF 17" OEM alloy.

The 2018 and up 17" Nissan rim very much looks aero optimized to me. This means that the EV01 with covers will likely very hard to differentiate from OEM with respect to overall aerodynamic drag. You are going to need to drive pretty fast too in order to see a difference. This is an excellent study : https://publications.lib.chalmers.se/records/fulltext/176302/176302.pdf

So a highway test at steady speeds will likely not be too illuminating. If the rims are 8 lbs lighter though, you should absolutely see less power required to accelerate them. So in a heavy urban stop/go cycle, they may actually show a bigger difference.

I'd be shocked and amazed if you don't see a measurable difference on the 30-60 runs with the lighter rims. It's a an easy test and I found these type of tests the easiest to compare when doing my VW Westfalia engine conversion. In that case I built up an audi i4 engine (including designing intake, welding custom exhaust etc.) and dropped it in place of the flat 4 wasserboxer engine. This dropped the acceleration from stock at 20.5 seconds, down to 13.3, and increased highway mpg to boot (very old page!): http://my.tbaytel.net/guskers/perform.html

I will do some 0-60 tests too. While the 17" have some aero qualities, the 16" rims (on the S+) have less, yet the S+ is noticeably more efficient. The 16s are a narrower tire too, which I believe helps.

Shipment arrival date moved to Monday.

No doubt, the 16" narrower wheels will be more efficient that 17" wider ones.

Ok, EV01s are on the car. Sadly a late Chicago snowstorm fouled my driving team for doing the pre-tests, so I will be missing key baseline data for testing the wheels. I had the existing ecopias moved over.

In terms of weight, the stock rims are 21.1 Lbs and the EV01s are 15.9. This is 16" to 16" on the S+. 20 Lbs unsprung weight reduction is always helpful.

More to come. I will put the covers on next week, but the non-covered look is growing on me.

https://drive.google.com/file/d/10XaT8JJTaNaZOiVFxTObEOejfFR8M2wP/view?usp=drivesdk

Separately, does anyone use power cruise control? I noticed this video had it as a sponsor, and that they used it for the Lesf vs. M3 race.

https://youtu.be/eJj09oDeVzQ

So I did a test without then with the covers on the EV01+ rims today. Enf efficiency came out per dash to be the same within .1 miles/kWh. Both 37 mile runs with the cruise control set at 65mph (2 loops of 9 miles in each direction north south for each run) came out today at 4.3 miles/kWh. Ambient and battery was at 55F. I have been trying to look for an equivalent run from last fall, and the closest I have is a run at a similar temp is at 93km/h, which netted 4.6-4.7 on the same loop, but only 1 time around which wasn't exactly apples to apples.

I also had a weird issue where the bms adjustment for this quarter started while I was on my second run, which messed up the GIDs used in Leafspy.

Will do some more testing this weekend, but gains appear to be subtle so far beyond the improvement in driving dynamics.

I really need warm temp high speed runs to feel see any measurable difference.

https://drive.google.com/file/d/10XaT8JJTaNaZOiVFxTObEOejfFR8M2wP/view?usp=drivesdk

Rotating mass is more of an issue in stop/go driving than constant speed on the highway. If your new wheels really are 5 pounds lighter (each), then you might get a little benefit in stop/go driving. I am not surprised that you are seeing very little difference in your highway tests.

So I have about a week of driving on my new wheel combo and I'm seeing about a 10% improvement in consumption but I also look forward to warmer weather because I have been driving in 45F - 59F weather with also some rain added in to drag numbers down.

The 17" OEM combo if TireRack's weight for the OEM Michelin specs are to be believed means that I went from a 47.2lb per corner to a 38.92lb per corner so a reduction of 8.28lb which is very noticeable during initial acceleration. basically I now get the "eagerness" of the car when Eco mode is turned off with the lighter combo while still in Eco mode.

I went from a 215/50/17 tire to a 205/60/16 tire and at the same 40psi cold psi the ride comfort is way higher but I'm presuming some of that is having full tread vs well worn OEM tire but the extra sidewall is certainly also helping there as well.

I don't drive my Leaf aggressively in corners but but dropping from a 8.5" section width to a 8.1" section width does not seem to be a negative and that's the base tire section width as well.

I will update in a few months as the weather warms in terms of consumption. I used to get 4.6-4.8 averaged over 900+ miles for the past two springs so I'm very curious to see what that will change to in a few months.

As we have both a Leaf with 17" wheels and 16" narrower wheels, I confirm, the smaller wheels increase your efficiency 6-10%. It's very noticeable at 70mph. What rims did you use?

Enjoy the boost.

Leftie, yep, my testing so far seems to show a small benefit around town, and hard to measure at highway speeds. Roll down does seem better, but I don't have the patience to do it scientifically. I do plan a "very" high speed test when it gets warmer (75mph) which I am hoping might yield .1 or so, but enjoying the wheels none the less. The good news is that I now have 16" rims free for the SV+ in a year or two when I need tires.

Leftie, yep, my testing so far seems to show a small benefit around town, and hard to measure at highway speeds. Roll down does seem better, but I don't have the patience to do it scientifically. I do plan a "very" high speed test when it gets warmer (75mph) which I am hoping might yield .1 or so, but enjoying the wheels none the less. The good news is that I now have 16" rims free for the SV+ in a year or two when I need tires.

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That was GerryAZ, not me.

DougWantsALeaf said:

As we have both a Leaf with 17" wheels and 16" narrower wheels, I confirm, the smaller wheels increase your efficiency 6-10%. It's very noticeable at 70mph. What rims did you use?

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http://www.veloxwheels.com/wheels/mantra

I went with these wheels because they were offered through Costco & they had a promo + a bonus promo for buying a set of tires with the wheels. I ended up paying $480+tax for the set of wheels & $1033 OTD.

I typically drive 60mph on the freeway & only about 30% of my miles is freeway. I have an older Prius that I tend to use more longer hwy scenarios. I have intentionally created my life around a 5-25 mile radius so my driving is often(20-25K miles/yr) but highly local

HerdingElectrons said:

...
The 17" OEM combo if TireRack's weight for the OEM Michelin specs are to be believed means that I went from a 47.2lb per corner to a 38.92lb per corner so a reduction of 8.28lb which is very noticeable during initial acceleration. basically I now get the "eagerness" of the car when Eco mode is turned off with the lighter combo while still in Eco mode.
...

Click to expand...

That's what I would have predicted. That 8lbs of rotating mass is very significant on acceleration. On the other end, you'll have less regenerative braking energy to recover. Given the inherent inefficiency of regen, better to save those electrons on acceleration. It's the same when you swap over to say larger disc rotors and brakes for a "performance" upgrade. Yes, you stop better, but almost always at the cost of acceleration.

Try those in gear acceleration times! Thanks again for posting. Very interesting stuff for a techno geek like myself.

Ok, I fixed fixed Google image permissions for the car pic with the ev01 wheels.

https://drive.google.com/file/d/10XaT8JJTaNaZOiVFxTObEOejfFR8M2wP/view?usp=drivesdk

Looks good!

I need to make time to take a pic of my wheels after I wash the car!

They look just fine Post a pic without the covers...just curious.

https://drive.google.com/file/d/1-YsKjNJhLMB13VIwK8BH5zKMfvE9ObKd/view?usp=drivesdk

Thanks for posting that

I figure they look a bit better without the covers? Getting the inserts color matched to the car might take that look up a notch again.

I did like them without the covers on. I debated whether I should have waited longer before fitting the covers.

It is about an hours work to add or remove the covers; a bit more effort than to take the Tesla Aero covers on and off.