fotajoye
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Re: LEAF 2 : What we know so far

Mon Mar 09, 2015 12:28 pm

NeilBlanchard wrote:Having a low Cd is the best way to extend the range for any given battery pack capacity. So, having a lower Cd means a longer range with an smaller pack; which means a lower price.

So, I hope they go in the direction of the Renault Eolab concept; which I think looks even better than the Sway concept.
The Cd has more of an effect on range at the higher speeds because of the square factor of the velocity; At 35 mph and below, it is almost negligible; even at 50 mph it is fairly minor. Also, a Cd of .28, which is what the Leaf has, is very good for a street car; Tesla's Cd is only .04 better, very minor. However, one improvement, that is estimated to improve range on any car by about 3% at speeds, is to replace the sideview mirrors with cameras.

Want to improve range? reduce the weight like BMW has on the i3 which weighs about 2,700 lbs which is about 500 lbs less than the Leaf. Another major factor, other than a higher battery energy density, is friction and the major device in friction is the tires which Nissan has already addressed with low rolling resistance tires. Some additional work can be done in the area of friction by eliminating the differential gearing and and the reduction gears and installing two smaller computer controlled and synchronized drive motors instead. Additionally lower friction lubricants can be used on all bearing surfaces.

There is also work proceeding to increase the efficiency and reduce the weight of the electronic devices: The first one that comes to my mind is to replace the Leaf's lead battery with a smaller, lighter Lithium battery. One reads a lot of about Lab work to reduce the heat losses, the size and weight of the Motor Control Unit, DC to Dc Inverter and on-board AC Charger by moving over to graphene devices. Hopefully one day this will be in mass production.

BTW, the AC Charger doesn't need to be on board the car. If one charges at home and uses quick charging stations for distance travels, you never use the AC Charger. You can hang it on the wall at home or use a small DC quick charger at home. Think about it. That's what racers do...saves weight and simplifies the design. And, if you just need to feel psychologically safe, you can build up a small AC trickle charger with a rectifier for comfort.

DanCar
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Re: LEAF 2 : What we know so far

Mon Mar 09, 2015 1:38 pm

fotajoye wrote:Having a low Cd is the best way to extend the range for any given battery pack capacity....
Agree! Call me boring, but skip the muscular look of the sway concept and give me the prius egg look. :)
2013 Leaf SL leased 3/10/2013
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hill
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Re: LEAF 2 : What we know so far

Mon Mar 09, 2015 2:39 pm

dhanson865 wrote:
hill wrote:
dhanson865 wrote:.....snip.............
"Kia tells us that the Soul EV will only be available in California, Oregon, New York, New Jersey and Maryland."

So for those of us in the other 45 US states the Soul EV doesn't exist as competition.

Though I hear they are selling it all over Canada, and parts of Europe. .......snip........
Kia is not saying they WON'T sell the soul ev in all 50 ... just not yet. It does take a bit to get techs up to speed. I will say this for Kia ... They're supporting Chademo 100kW systems in the EU. I don't see Nissan doing that. But with a puny Leaf battery (even NEW ... much less once it's lost 20% capacity) why on earth would Nissan support bigger charge power.
No they say they will expand the list of states sometime in the next month but we don't know if that will be 10 states or what. I seriously doubt it will be 50 states because of this: . . . . . . . . snip . . . . .
That's fine to doubt. Ironically though, the mentioning of how dealers were surprised about "demand". I've never seen a big inventory of Soul EV's on the Kia Lots - maybe one or two. And in that same vein, you find auto sites claiming the plug-in-Prius is the "Best Selling Car". All that means in the authors' twisted way of looking at it is that they only sell 'em in a hand full of states ... and relatively low manufacturing quantities get bought up ... so they don't sit on the lot very long. Big deal. Perhaps the reason Kia Soul Dealerships are surprised simply means, "wow!! we sold both of the ones we got!!". That kind of data twisting is really meaningless. If/when Kia bumps up production and sales wow the dealerships ... then it means something.

That Soul EV's are being bought up means folks want more range. Only getting more range (with a still decent price) will keep the Leaf ahead of the Soul EV if/when they sell in more & more states.
.

GRA
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Re: LEAF 2 : What we know so far

Mon Mar 09, 2015 4:54 pm

fotajoye wrote:
NeilBlanchard wrote:Having a low Cd is the best way to extend the range for any given battery pack capacity. So, having a lower Cd means a longer range with an smaller pack; which means a lower price.

So, I hope they go in the direction of the Renault Eolab concept; which I think looks even better than the Sway concept.
The Cd has more of an effect on range at the higher speeds because of the square factor of the velocity; At 35 mph and below, it is almost negligible; even at 50 mph it is fairly minor. Also, a Cd of .28, which is what the Leaf has, is very good for a street car; Tesla's Cd is only .04 better, very minor. However, one improvement, that is estimated to improve range on any car by about 3% at speeds, is to replace the sideview mirrors with cameras.
The thing is, you need the long range at high speed, not when trolling around town. Around town it's fine to have the Cd of a Hummer, because you're unlikely to drive far enough to reach your max range, and you benefit from regen. At freeway speeds that's not the case, and any BEV that is presented as a complete replacement for an ICE has to have the range where it matters. All but three states west of the Mississippi [Edit: should read 'Missouri'] have rural interstate speed limits of 75 or 80 mph, and most people drive about 5 mph over that. Even at 70 mph that .04 increase in Cd is going to make a significant difference in freeway range, far more than the extra weight of the battery decreases it (as you mentioned below).
fotajoye wrote: Want to improve range? reduce the weight like BMW has on the i3 which weighs about 2,700 lbs which is about 500 lbs less than the Leaf. Another major factor, other than a higher battery energy density, is friction and the major device in friction is the tires which Nissan has already addressed with low rolling resistance tires. Some additional work can be done in the area of friction by eliminating the differential gearing and and the reduction gears and installing two smaller computer controlled and synchronized drive motors instead. Additionally lower friction lubricants can be used on all bearing surfaces.
Last edited by GRA on Mon Mar 09, 2015 6:12 pm, edited 1 time in total.
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

GRA
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Re: LEAF 2 : What we know so far

Mon Mar 09, 2015 4:56 pm

fotajoye wrote:
GRA wrote: Which design profile do you think will have lower drag due to the roofline, and which more rear headroom, AOTBE: a modern Jaguar sedan, with a smooth curvature down to a high trunk: http://images.thecarconnection.com/lrg/ ... 6058_l.jpg" onclick="window.open(this.href);return false;

or a 1980 Jag, with an abrupt discontinuity and a low trunk? http://invimg1.autofunds.com/InventoryI ... 472014.jpg" onclick="window.open(this.href);return false;

Compare the modern Jag to the Tesla S: http://www.blogcdn.com/www.autoblog.com ... 336754.jpg" onclick="window.open(this.href);return false;

There's a reason the Prius and Insight look so much alike; there's only so many ways to reduce turbulence (-> drag) at the rear end of the car. Same goes for a sedan-style body, which is why cars designed for minimum aero resemble each other so much.
I know that. And, the amount and configuration of the interior space is one of the compromises to a street car's aerodynamics that dictates the shape of the roof, etc. The Tesla has a CD of .24 and the Leaf a CD of .28-.29. The difference is hardly worth the inconvenience. We are talking practical street cars here not expensive toys for the rich. If you want to introduce that bag, that a different segment altogether and I'll be glad to discuss and debate aerodynamic and airflow physics as I have racing and engineering knowledge of the subject; but, that's not what this thread is about. This thread is about: Leaf 2: What We Know.
Okay, you've lost me. ISTM that you are agreeing with evnow (and me), so why the objection to his post?

Edit: Here's an article re the Model S and its drag reduction during development, which was initially 0.32, then reduced to 0.27 and finally to the current value of 0.24:
Digital Wind Tunnel Video Shows Aerodynamics Of Tesla Model S
http://insideevs.com/digital-wind-tunne ... a-model-s/" onclick="window.open(this.href);return false;
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

NeilBlanchard
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Re: LEAF 2 : What we know so far

Tue Mar 10, 2015 9:53 am

fotajoye wrote:
NeilBlanchard wrote:Having a low Cd is the best way to extend the range for any given battery pack capacity. So, having a lower Cd means a longer range with an smaller pack; which means a lower price.

So, I hope they go in the direction of the Renault Eolab concept; which I think looks even better than the Sway concept.
The Cd has more of an effect on range at the higher speeds because of the square factor of the velocity; At 35 mph and below, it is almost negligible; even at 50 mph it is fairly minor.
Aero drag contributes ~50% of the load on the drivetrain at ~30MPH. It is the majority of the load; the opposite of negligible. At 55MPH, it is ~75% of the load, and it goes to almost 90% at 75MPH.

A Cd drop of 0.04 is significant.

Oh, and the Leaf was measured by Car & Driver to be 0.32; while confirming the Cd of the Tesla Model S is 0.24. http://www.caranddriver.com/features/dr ... rison-test

The Tesla Model S is TIED with the gen 3 Prius for CdA. Think about that for a minute.

Graffi
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2017 Nissan Leaf: What We Know So Far About New Electric Car

Sat Mar 14, 2015 8:53 am

https://autos.yahoo.com/news/2017-nissa ... 49117.html" onclick="window.open(this.href);return false;

Saw this on Yahoo a few minutes ago.
2013 SL Metalic Slate - We LOVE our Leaf
MFG 08/13 Dlv 09/06/13 @ 10 mi
# 77 100 mile club
# 10 200 km club

2017 Tesla S 75D Pearl White
Delivered 5/16/17 @ 900 mi
Tesla Model 3 on order awaiting 200+ mile range Nissan Leaf

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evnow
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Re: 2017 Nissan Leaf: What We Know So Far About New Electric

Sat Mar 14, 2015 9:10 am

Graffi wrote:https://autos.yahoo.com/news/2017-nissa ... 49117.html

Saw this on Yahoo a few minutes ago.
This is a reprint of the poor GCR article.
1st Leaf : 2/28/2011 to 5/6/2013
2nd Leaf : 5/4/2013 to 3/21/2017
Volt : 3/25/2017 to 5/25/2018
Model 3 : 5/10/2018 to ?

fotajoye
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Re: LEAF 2 : What we know so far

Sat Mar 14, 2015 11:41 am

NeilBlanchard wrote: Aero drag contributes ~50% of the load on the drivetrain at ~30MPH. It is the majority of the load; the opposite of negligible. At 55MPH, it is ~75% of the load, and it goes to almost 90% at 75MPH.

A Cd drop of 0.04 is significant.

Oh, and the Leaf was measured by Car & Driver to be 0.32; while confirming the Cd of the Tesla Model S is 0.24. http://www.caranddriver.com/features/dr ... rison-test....
Aerodynamic load is 50% at 30 mph; that's interesting; where did you find that? Also, the Leaf Cd is quoted in Nissan literature as .28-.29. Perhaps the cover article you read is in error. A truth often quoted is the aerodynamic drag is it's 4 times higher at 70 mph than at 35 mph; I believe that; but, I doubt the 50% figure; seems to me that figure would be specific to a particular car because of the other load variables. Here again velocity is the big factor in the calculations and I agree a .04 Cd is significant at 100 mph and would be a major concern at 200 mph on the salt flats.

GRA
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Re: LEAF 2 : What we know so far

Sat Mar 14, 2015 12:59 pm

fotajoye wrote:
NeilBlanchard wrote: Aero drag contributes ~50% of the load on the drivetrain at ~30MPH. It is the majority of the load; the opposite of negligible. At 55MPH, it is ~75% of the load, and it goes to almost 90% at 75MPH.

A Cd drop of 0.04 is significant.

Oh, and the Leaf was measured by Car & Driver to be 0.32; while confirming the Cd of the Tesla Model S is 0.24. http://www.caranddriver.com/features/dr ... rison-test....
Aerodynamic load is 50% at 30 mph; that's interesting; where did you find that? Also, the Leaf Cd is quoted in Nissan literature as .28-.29. Perhaps the cover article you read is in error. A truth often quoted is the aerodynamic drag is it's 4 times higher at 70 mph than at 35 mph; I believe that; but, I doubt the 50% figure; seems to me that figure would be specific to a particular car because of the other load variables. Here again velocity is the big factor in the calculations and I agree a .04 Cd is significant at 100 mph and would be a major concern at 200 mph on the salt flats.
As the C&D article mentions, Cd will vary depending on which wind tunnel its tested in, which is why manufacturers only trust their own measurements of it. In this case, C&D tested all the cars in the same tunnel, so there was no variation due to the tunnel.

As to aero drag being 50% @ 30 mph, obviously it varies from car to car, but the power crossover point (where it takes more power to overcome drag than Rr) is usually in the 30-40 mph range. You can also see that the power required due to drag scales as the cube of the speed, not the square: 100 mph/70 mph is about 1.43, and the cube of that is just about 3, which matches up with the 42 hp required for the Model S @ 100 mph versus the 14 required @ 70, and the LEAF's 53 hp vs. 18 hp ditto.

What the C&D tests show is that the Model S (air suspension) only needs about 78% of the power (14 hp or 10.44 kW, versus 18hp or 13.43kW) as the LEAF does @ 70 mph to overcome drag. Rolling resistance isn't measured by these tests, obviously, and I'd expect the LEAF to come out ahead there given its much lighter weight etc.

Considering only the drag component, assuming you could use all of a LEAF battery's 24 kWh you could drive about 1.78 hours at a constant 70 mph; the Tesla S 85 could do that for about 8.1 hours. This is a ratio of about 4.55, while the difference in the battery capacity of the two cars is a ratio of only 3.54, giving the Model S a bonus of about 28.5% range compared to if it needed the same power to overcome drag as the LEAF. Usable battery capacity is less, obviously, but the relative rate at which you discharge the battery affects its capacity (higher rate = lower capacity), which would, by itself, give the Tesla with its much larger pack more usable capacity for any given total capacity at the same actual (not relative) rate of discharge, let alone a lower one. If that's clear as mud, put it this way: the LEAF, at 13.43 kW, has a relative rate @ 70 mph of C/1.78 (higher), while the Tesla has a relative rate of C/8.1 (lower).
Guy [I have lots of experience designing/selling off-grid AE systems, some using EVs but don't own one. Local trips are by foot, bike and/or rapid transit].

The 'best' is the enemy of 'good enough'. Copper shot, not Silver bullets.

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