Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 09-12-2017, 02:12 AM   #1 (permalink)
Tesla Inside
 
RAV4 EV's Avatar
 
Join Date: Nov 2016
Location: Los Angeles
Posts: 17
Thanks: 0
Thanked 2 Times in 2 Posts
Estimating range gain between different 40kWh E-Vehicles

Why is it that the 40kWh Model S is EPA rated 139 miles while the Rav4 EV is rated 103 miles yet their usable kwh capacity is about the same? For the RAV4 EV it is 41.8kwh and the Model S 40 it is believed to be software capped either at or close to 40kWh.





Model S 40 RWD

Weight: 4,647.3 lbs
196″ L x 77″ W x 57″ H
Drag Coefficient of 0.24

Rav4 EV FWD

Weight: 4,032 lbs lbs
180″ L x 72″ W x 66″ H
Drag Coefficient of 0.30


Here is the interesting thing. The Rav4 EV is:

16" Shorter
5" Narrower
9" Taller (It's an SUV so it can be lowered.)
615.3 Lbs Lighter
FWD instead of RWD
Aero Drag Difference is 0.06

Now for the tires!

225/65R17 Rav4 EV
245/45R19 Model S
245/35R21 Model S

This means

Width of tires is Smaller
Aspect Ration is higher which means less contact patch on the ground ... less rolling resistance?
Tire Diameter is smaller

As for which weigh more... that I am not sure, but I do have a quote:

Quote:
"19" cast aluminum wheels with all-season tires (Goodyear Eagle RS-A2 245/45R19). Note: optional 21" wheels come with Continental Extreme Contact DW 245/35R21 tires"

According to "http://www.Teslamotorsclub.com/showwiki.php?title=Model+S+-+FAQ":
Quote:
--
"Width:
19x8 for 19" wheels
21x8.5 for 21" wheels

Weights:
19" Wheels: 13.74kg ~30lbs each (according to a Tesla engineer)
19" All Season Tires: 27lbs each (according to Tire Rack for Eagle RS-A2 245/45 19")

21" Wheels: 35lbs
21" Continental ExtremeContact DW Tires: 26lbs"
I'm not sure if the RAV4 EV Wheels are Aluminum or some other heavier alloy. Here is another quote:


Quote:
On an ICE forum they said the 17" limited wheels weighed 23 lbs 6 oz each. With stock tires someone said it was 51 lbs. I could be wrong but with a pair of lightweight wheels from TireRack you could save quite a bit of weight.....

Again, assuming its the same wheel as the ICE limited, its a 17x7" wheel. The same width as the Enkei Racing RPF1's which are the lightest wheels TireRack offers for the Rav4.
The Michelin Energy Saver A/S tires are 26 lbs each.
The Bridgstone Ecopia EP422 tires are 24 lbs each.
There are plenty more options but I know those are two popular tires.

So with Enkei Racing RPF1's and Bridgstone Ecopia EP422 your total would be 47lbs, 6 oz roughly.
If the stock set up is 51 lbs you'd be saving about 4 lbs 6 oz.


Quote:
I'm looking into this again. I just weighed my stock wheels and tires, they are 45.6lbs.

The 16" Enkei RPF1's 17x7" are 14.6lbs
Ecopia EP422 are 25lbs
Champion Fuel Fighter tires are 25lbs

That would be 39.6lbs total, per wheel. A savings of only 6lbs per wheel.

225/65R17 Rav4 EV 45.6lbs lbs Total?
245/45R19 Model S 30+27 lbs
245/35R21 Model S 35+26 lbs




Model S Frontal Area is 25.2 square feet and fontal area drag is 6.2 Square feet.
https://www.tesla.com/sites/default/...n-the-road.pdf


Rav4 EV Frontal Area is a guess, but I did find something on the 2006 rav4 limited gasser but its only an estimate:
Drag area, Cd (0.33) x frontal area (30.4 sq ft, est ) . . . . 1 0.0 sq ft
http://media.caranddriver.com/files/...-v-6-specs.pdf

Now there are articles out there speaking a lot about how the engineers at Toyota redid the front facia of the RAV4 EV to be more aerodynamic and also picked the most aerodynamic head lights and smaller side mirrors. So I think the Frontal Area would be slightly smaller?


Interestingly the Toyota Dismantling Manual says: A fully charged RAV4 EV will travel
approximately 152 miles (245 km) http://prius20.ru/instructions/disma...vdisman2nd.pdf





Looking at things this way it would seem the main thing is the higher drag, so if we were to lower the RAV4 EV's Drag by 0.06 to be the same as the Model S does this mean we would have closer range in terms of what the EPA states? I understand the Frontal Area would be harder to reduce, so we'd likely need more cd to hit similar numbers, but about how much?

I think the rav4 EV is smaller than the Model S. It is shorter and less wide and in terms of height ours is an SUV so it comes naturally high standing. If the RAV4 EV were to be lowered it might just stand closer to the Model S. Why then is there such a noticeable gap in range?

If a reduction in drag of 0.06 equals around +36 miles of range can we extrapolate this to see just how much range we can get from a RAV4 EV with a drag co of 0.10?

6000.06=36
6000.2=120 ?

I'd be quite happy with an extra 120 miles for a total range of 223 miles.





With these two pictures I can see the wider tires and wider body of the S, but also the shorter stance. Head lights seem to stick out more roughly on the RAV4 EV. Also, front bumper lines near headlights look rough compared to Model S. Hood Gap on Rav4 EV is also very noticeable. Wipers stick out a little.

Thoughts?

__________________
0.30 Cd
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 09-12-2017, 04:06 AM   #2 (permalink)
EcoModding Apprentice
 
Join Date: Jun 2010
Location: Australia
Posts: 177

Delivery 'Boy - '86 Suzuki Mighty Boy
90 day: 37.15 mpg (US)

SkipSwift - '13 Suzuki Swift GL
90 day: 35.44 mpg (US)
Thanks: 0
Thanked 33 Times in 27 Posts
Multiply Cd by A to get CdA (total area drag)

Tesla = 0.24*25.2 = 6.048
Rav4 = 0.3*30.4 = 9.12

9.12/6.05= 151% drag. The Rav4 has 50% more aero drag than the Tesla
44/36 (kw/h per 100mile) = 122% energy usage. Rav4 has 22% more energy usage.
__________________







Quote:
Originally Posted by Crazyrabbit
In God we trust. All others: bring data
  Reply With Quote
The Following 3 Users Say Thank You to BLSTIC For This Useful Post:
Daox (09-12-2017), redpoint5 (09-12-2017), Xist (09-12-2017)
Old 09-12-2017, 04:27 AM   #3 (permalink)
Master EcoModder
 
JockoT's Avatar
 
Join Date: Jun 2017
Location: Scotland
Posts: 420

All That Jazz - '06 Honda Jazz i-DSI S
Team Honda
90 day: 49.61 mpg (US)
Thanks: 23
Thanked 71 Times in 56 Posts
There is also the efficiency of the drive train to take into account, the amount of regenerative braking, the efficiency of the battery cooling and possibly other factors that effect the range.
__________________
People Think They Are Thinking When They Are Merely Rearranging Their Prejudices


  Reply With Quote
The Following User Says Thank You to JockoT For This Useful Post:
Xist (09-12-2017)
Old 09-12-2017, 04:33 AM   #4 (permalink)
EcoModding Apprentice
 
Join Date: Jun 2010
Location: Australia
Posts: 177

Delivery 'Boy - '86 Suzuki Mighty Boy
90 day: 37.15 mpg (US)

SkipSwift - '13 Suzuki Swift GL
90 day: 35.44 mpg (US)
Thanks: 0
Thanked 33 Times in 27 Posts
And weight. You get some energy back from regen, but not all of it, so more energy to accelerate is still more energy used.
__________________







Quote:
Originally Posted by Crazyrabbit
In God we trust. All others: bring data
  Reply With Quote
The Following User Says Thank You to BLSTIC For This Useful Post:
Xist (09-12-2017)
Old 09-12-2017, 10:38 AM   #5 (permalink)
Master EcoModder
 
JockoT's Avatar
 
Join Date: Jun 2017
Location: Scotland
Posts: 420

All That Jazz - '06 Honda Jazz i-DSI S
Team Honda
90 day: 49.61 mpg (US)
Thanks: 23
Thanked 71 Times in 56 Posts
Quote:
Originally Posted by BLSTIC View Post
And weight. You get some energy back from regen, but not all of it, so more energy to accelerate is still more energy used.
I appreciate that, What I was meaning is the level of regeneration. If you have it set high you hardly ever have to use the brakes. If it is low then you brake a lot more. It isn't so much the regen that helps. It is the lack of energy expended through braking that can make a difference.
__________________
People Think They Are Thinking When They Are Merely Rearranging Their Prejudices


  Reply With Quote
Old 09-12-2017, 12:26 PM   #6 (permalink)
Administrator
 
Daox's Avatar
 
Join Date: Dec 2007
Location: Germantown, WI
Posts: 10,224

CM400E - '81 Honda CM400E
90 day: 39.62 mpg (US)

Daox's Grey Prius - '04 Toyota Prius
Team Toyota
90 day: 49.53 mpg (US)

Daox's 04 Civic - '04 Honda Civic DX
90 day: 44.13 mpg (US)

Daox's Insight - '00 Honda Insight
90 day: 64.33 mpg (US)
Thanks: 1,744
Thanked 1,981 Times in 1,210 Posts
Its all about the aerodynamics as BLSTIC said.
__________________
Current project: Heating the manual trans with engine coolant
  Reply With Quote
Old 09-12-2017, 01:15 PM   #7 (permalink)
...beats walking...
 
Old Tele man's Avatar
 
Join Date: Jul 2009
Location: Tucson, AZ
Posts: 5,918
Thanks: 158
Thanked 1,362 Times in 1,013 Posts
Quote:
Originally Posted by Daox View Post
Its all about the aerodynamics as BLSTIC said.
It's about the aero at speeds above about 45 mph, but it's always about weight acceleration (mass) at ALL speeds.
__________________
2014 Toyota Prius 1.8L eCVT
2009 Pontiac Vibe 1.8L/SFI 4A
2004 Pontiac Vibe 1.8L/MFI 4A

2011 Chevrolet LTZ Cruze 1.4LT 6A
1971 Dodge Charger 318 3A
1970 Plymouth AAR 'Cuda 340/6BBL 4M
1968 Dodge Charger 383 3A
1967 Plymouth Barracuda Formula S 383 4M
1965 Plymouth Barracuda Formula S 273 4M
  Reply With Quote
Old 09-12-2017, 03:09 PM   #8 (permalink)
EcoModding Newb
 
redpoint5's Avatar
 
Join Date: Aug 2010
Location: Oregon
Posts: 2,790

Acura TSX - '06 Acura TSX
90 day: 31.25 mpg (US)

Lafawnda - '01 Honda CBR600 F4i
90 day: 47.32 mpg (US)

Big Yeller - '98 Dodge Ram 2500 base
90 day: 21.82 mpg (US)

Camry - '98 Toyota Camry
90 day: 27.09 mpg (US)

Prius Plug-in - '12 Toyota Prius Plug-in
90 day: 68.94 mpg (US)
Thanks: 1,081
Thanked 858 Times in 568 Posts
Nah, weight hardly matters at sustained speeds. Aero is always important, whereas weight is really only a penalty in stop and go driving.

As pointed out above, weight and aerodynamics are not the only considerations.

The Leaf, for instance, uses induction motors instead of permanent magnet. This is a less efficient motor design and affects the MPGe.
__________________
Gas and Electric Vehicle Cost of Ownership Calculator







Give me absolute safety, or give me death!
  Reply With Quote
Old 09-12-2017, 04:53 PM   #9 (permalink)
Tesla Inside
 
RAV4 EV's Avatar
 
Join Date: Nov 2016
Location: Los Angeles
Posts: 17
Thanks: 0
Thanked 2 Times in 2 Posts
Quote:
Originally Posted by JockoT View Post
There is also the efficiency of the drive train to take into account, the amount of regenerative braking, the efficiency of the battery cooling and possibly other factors that effect the range.
The rav4 ev has the tesla power train from the same year which is the 40kwh model, so unless there were any drastic changes the power train should be the same. Main difference would be FWD Vs RWD.

Quote:
Originally Posted by BLSTIC View Post
And weight. You get some energy back from regen, but not all of it, so more energy to accelerate is still more energy used.
Quote:
Originally Posted by Old Tele man View Post
It's about the aero at speeds above about 45 mph, but it's always about weight acceleration (mass) at ALL speeds.

In other words timing the red light in N is the best thing to do which is what I try to do! Also, the RAV4 EV is lighter than the Model S by a few hundred pounds listed above. The Model S is a software limited 60kw pack. Rav4 ev is 41kwh so less weight.

Quote:
Originally Posted by redpoint5 View Post
The Leaf, for instance, uses induction motors instead of permanent magnet. This is a less efficient motor design and affects the MPGe.
From a previous Tesla blog the induction motors are better for high performance. Maybe this is why the 0 to 60 difference between the Bolt and the RAV4 EV is only 0.5 even though the RAV4 EV is bigger/heavier/Less power from battery pack.

Quote:
Originally Posted by BLSTIC View Post
Multiply Cd by A to get CdA (total area drag)

Tesla = 0.24*25.2 = 6.048
Rav4 = 0.3*30.4 = 9.12

9.12/6.05= 151% drag. The Rav4 has 50% more aero drag than the Tesla
44/36 (kw/h per 100mile) = 122% energy usage. Rav4 has 22% more energy usage.
It's so hard to believe that the Aero is costing so much when the only two cons of the RAV4 EV is the height(Frontal Drag Increase) and the 0.06 drag difference from the body shape. The Height being what is affecting the front drag so much, right? From the other stats the RAV4 EV is narrower and shorter and weighs less. It takes so big of a penalty just from the front drag which I think is a bit unfair :P.

So would lowering the RAV4 EV closer to the ground lower the Frontal drag? Would this help by hiding the wheels into the body? It does have a belly pan on the bottom (Engineers added it for the ev). Also, the Frontal drag estimate was from the gasser rav4... I feel it could be potentially smaller for the rav4 ev. One of the things they did ont op of picking aero headlights and reshaping the nose was add small mirrors from the korea market rav4. So... frontal drag must be smaller, no?
__________________
0.30 Cd
  Reply With Quote
Old 09-12-2017, 05:54 PM   #10 (permalink)
EcoModding Apprentice
 
Join Date: Jun 2010
Location: Australia
Posts: 177

Delivery 'Boy - '86 Suzuki Mighty Boy
90 day: 37.15 mpg (US)

SkipSwift - '13 Suzuki Swift GL
90 day: 35.44 mpg (US)
Thanks: 0
Thanked 33 Times in 27 Posts
It must be. Unless there's some huge rolling resistance or inefficient calibrations going on, it *must* be either weight or drag if they use the same powertrain. No one ever lost economy by making a car lighter, so there's your answer.

It's roughly the difference between an upright bicycle (dutch style thing) and someone on a time trials bike.

__________________







Quote:
Originally Posted by Crazyrabbit
In God we trust. All others: bring data
  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com