# longest known range for a DIY EV, streamlining?



## Karter2 (Nov 17, 2011)

Tesla's range is simply the result of using the largest capacity , and very expensive, battery in any commercial EV car..90kWhr .
100+ mile range is readily attainable if you can afford enough battery capacity and/or compromise on performance expectations ( speed, air con, etc)
EG, you could convert a pick up truck or van with something like a Leaf motor and drive train, then put 2 leaf battery packs ( 50kWhr) in the back, and easily get your 100 miles !
Not very glamerous but you get the picture ?
You need to define your actual requirements in the vehicle.
100 miles on 20 kWhr is also easy to do with the right vehicle ( remember that is at least 100kg of cells as a minimum ) but something a simple as a trike could work at low speed (< 50mph)
Some of the Corbin/Myer EV's would make a sensible base if you have the budget.
I dont think the F170 , or any go kart, is a practical or safe basis for any road vehicle, and certainly wont get you a 100 miles in any comfort !


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## runcyclexcski (Mar 21, 2016)

Hey, many thanks for the response! 

Is there a big difference between Leaf's and Tesla packs, in terms of energy density? One can now get battery packs claiming to have 20-Ah at 5V, for $20 a piece. That's 100 W-H. 100 of these things should give 10kW-h for $2,000, may be even less in bulk. I guess they are not as reliable as Leaf's...

http://www.aliexpress.com/item/Port...Powerbank-cargador-portatil/32515483610.html?

The safety on the road is something I am researching on at the moment. If we consider the motorcycle the unsafest vehicle legally on the road, I do not see how a kart is less safe than a motorcycle: they are similar in size/weight, but a kart has 4 wheels instead of 2, and can be made enclosed -> more resistant to debris and more resistant to skids in turns etc. 

Here is a research paper on vehicle-to-vehicle collisions citing a linear gain in safety for bigger vehicles, but the gains were outweighed by the aggressiveness of driving (below can be googled): 

Title: Vehicle compatibility in car-to-car collisions
Subtitle: Literature review in the framework of the European research project
“Improvement of crash compatibility between cars”, Workpackage 1
Author(s): Jan van der Sluis
Research manager: Boudewijn van Kampen
Project number SWOV: 69.870
Project code client: Contract No. RO-97-SC.1064
Client: This project was funded by the European Commission DGVII under the
Transport RTD Programme


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## ishiwgao (May 5, 2011)

runcyclexcski said:


> Thus, I wonder what the longest known range of self-bult EVs is. Has anyone been able to approach, or even beat, Tesla's range, and, if yes/no, can we learn from that positive/negative experience?


Hello and welcome. From your questions, I'm guessing you aren't all that familiar with vehicle mechanics and vehicle parts. Do try to read up on all these, even from Wikipedia and Google search some articles and you'll get your answers pretty quickly. 

as far as battery and range goes, as what some other members have mentioned here, yes range is proportional to batteries, so Tesla can have many times the range compared to other EVs because of the much bigger battery they have. maybe there are other DIY conversions that have more range than Tesla, but that is not a good comparison. To make the question more fair, you should be asking which DIY conversion resulted in a better efficiency (Wh/mile) than Tesla.



> I wonder if streamlining one's DIY EV and making it light can permit the use of a smaller (10kW) motors and smaller batteries (<20 kWH). .....
> I am thinking to make it a 1-seater > smaller frontal area>less drag. The reduced weight would be problematic at high speeds/side winds, hence the shape becomes even more important.


To give a background to your question quoted above and continue from my paragraph above, range is also a subset of many other things in the car, e.g. weight, drag, motor efficiency etc. all these affects the amount of energy u use in pushing the car forward. Tesla has quite a good drag coefficient with the Model S, so that's why it also requires less energy to drive it. 

There are many DIY conversions that have resulted in a very long tail to improve aerodynamic efficiency. I forgot the exact term used, something like boattail if I can recall. the idea is to extend the back of the car to follow the streamline of the air flowing around the car to reduce turbulence behind the car and hence drag. go look these up too if this is the kind of car you want. some people (many people in fact) think it looks a little unsightly. i guess it depends on your purpose.

to answer your question above, of course using smaller motors (probably resulting in better efficiency) and smaller batteries (less weight) and less frontal area (less drag) will definitely result in the car using less overall energy to push it forward, so you will get more efficiency in driving the vehicle (lower Wh/mile). Also as you've mentioned, the lesser weight will cause the car to be more unstable at high speeds, and this is the whole idea behind race cars and them generating downforce using wings and other aerodynamic stuff. race cars are light, but travel at high speeds and needs to be stable. If you can design your car to do the same (of course, NOT easy to do. requires a lot of time and money), then you will be safe at high speeds.



> Are there any wind tunnel simulators, so that I can test different designs before commuting to building one (molds etc)?


if I'm understanding your question right, usually before an actual wind tunnel test, the virtual car model goes through many more hours of fluid simulations using a fluid dynamics software. in order to use this, you first need to learn a lot about aerodynamics, car shapes etc and then learn the CAD software and fluid dynamics software, and then put everything together and start trying out everything. it won't take a month to learn. more like a few years (for 1 person to learn everything). if you have a team or something, that will more likely be easier.


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## Duncan (Dec 8, 2008)

Hi,
Look up Solar Racers - they are electric vehicles that can travel at a fair speed (60kph+) just using the sun,

The Aptera is not a good example - the funny front wheels reduce frontal area BUT with a proper "streamliner" frontal area is not as important as avoiding the horrible wind flow where those wheels join up with the body


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## miscrms (Sep 25, 2013)

IMHO the danger of driving something as small as a kart on the roads is going to be that you are nearly invisible to other drivers. Much less visible than a motorcycle, and I would argue this is already the greatest danger to motor cycle drivers. Depends on your own comfort with risk, and where you plan to drive I suppose.

If you are serious about pushing the bounds on efficiency / range, I'd also be looking at something with <4 wheels to reduce rolling friction. You're also going to want to go with a wheel type that has low rolling resistance tires and hubs available for it, something I'm not sure you'd find for a cart. Electric motorcycles can already approach ~100Wh/mi, even with their poor aerodynamics. That would give you ~200 mile range if you could work in a whole Leaf pack. A design with 2 or 3 wheels, with an aerodynamic shell should be able to exceed that, and/or let you reduce battery size.

Again if you really want to push it, you might even consider something bicycle part based like these velomobiles. There is already a lot of work put in to designing bicycle components that minimize weight and mechanical losses, since human power machines are pretty underpowered and there's a big market for go faster bikes.
http://www.lowtechmagazine.com/2010/09/the-velomobile-high-tech-bike-or-low-tech-car.html
http://www.lowtechmagazine.com/2012/10/electric-velomobiles.html










I would think taking one of those and fully electrifying could be pretty amazing.


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## Karter2 (Nov 17, 2011)

runcyclexcski said:


> Hey, many thanks for the response!
> 
> Is there a big difference between Leaf's and Tesla packs, in terms of energy density? One can now get battery packs claiming to have 20-Ah at 5V, for $20 a piece. That's 100 W-H. 100 of these things should give 10kW-h for $2,000, may be even less in bulk. I guess they are not as reliable as Leaf's...
> 
> ...


Ahh !...if only it were true !
20Ahr in a pack that small defies all the laws of present battery technology ?
I would be willing to bet that it is actually 2 Ahrs.....if that !

Tesla and Leaf packs are very different in design , and type of cells used
( search on here for more info). With the Leaf being the more available fron vehicle breakers. Costs are about $100 /kWhr for the Leaf and double that for the Tesla modules if you can find them.


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## Matej (Dec 4, 2015)

VW is supposedly working on a 300+mile EV that will recharge in 15 minutes.
http://www.autocar.co.uk/car-news/new-cars/vw-plans-radical-new-electric-vehicle-2019


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## Duncan (Dec 8, 2008)

Matej said:


> VW is supposedly working on a 300+mile EV that will recharge in 15 minutes.
> http://www.autocar.co.uk/car-news/new-cars/vw-plans-radical-new-electric-vehicle-2019



Yes - what a 90Kwhr pack that can recharge in 15 minutes
That is 360Kw!!!!!
You will need s Super Supercharger for that

The trouble with articles like that is that they don't seem to understand that the current limitation is NOT the battery - the main limitation is in the charger or getting the power to the charger

Your house is limited to about 20Kw - and you would need a special line and plug to get that much


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## gunnarhs (Apr 24, 2012)

runcyclexcski said:


> Hi all,
> 
> I am yet another newbie researching on EV self-builds. If I commit to my own build, I would use off-the shelf parts as much as I can, and try to build something unique (otherwise, what's the point). The 'unique' part I want to focus on is having a long range -- 100+ miles. Thus I began by downloading all 250 Tesla patents, since their car has the best range of all commercial EVs (AFAIK).
> 
> ...


Hi 

a lot of interesting questions here.
You can find a lot of stuff if you search in the Forum here about range of both DIY - and OEM - cars but the problem is usually that the cars and the environment differ a lot. Meaning a Nissan Leaf can have a range of 200 km /per 22 kWh Pack in ideal temperature on ideal Track if driven in Japanese cycle (where the car is mostly in the Speed range of 40 -70 km/h) but driven in Iceland at Winter-time ( 0 °C ) at same car has about 120 km Range More about here https://en.wikipedia.org/wiki/New_European_Driving_Cycle

So when looking at range you have to make the car driving the same standardized cycle or when comparing progress of your own car the km/kWh proportion as pointed out here in above comments. Soon you will realize that the OEM-specs will differ up to 50% from reality (meaning a 150 km range claimed in becomes usually less than 100 km).

We did some tests a few years ago where we drove different cars (OEM and converted DIY) on a predefined cycle under same temperature and similar weather condition. Maximum speed was 100 km/h and most time speed was under 70 km/h so aerodynamics efficiency (drag) was not tested fully.

The best result was the Tesla , doing 10 km/kWh/1000 kg
The best DIY had 8 km/kWh/1000 kg
OEM cars (Nissan Leaf 2011 , Mitsubishi MIEV 2010, etc) had 5-6 km/kWh/1000 kg

Breaking it down to the electric drive:

Low speed / Partial load efficiency: Permanent-magnet motors ruled (in all OEM)
High Speed / Full load efficiency : Induction motors ruled.
Normal (brushed) DC drives were better than expected but still inferior
Overall best performance (besides Tesla) surprise surprise, the DC Sep Ex-Motor - drive !!!

Breaking it down to Phrases and reality

What they say (said) :
"OEM - tests are the most reliable as they have the best equipment, the best staff and their advanced environment repeatedly produce the same result"

What is the truth:
Only performance on the road counts, tests are better done by independent parties.

What they say (said) :
"Due to our new electric drive technology we reach over 90% efficiency from charge to drivetrain-output"

What is the truth:
The best total efficiency of the electric cars is about 80%, normal is 65-70%.

The limit now for normal cars seems to be set by Tesla 10km/kWh/1000kg and 80% drive train efficiency

So far we are talking about "normal" cars, meaning at least 4 person vehicles with full raod permission. In case of special cars , like small Solar vehicles or other types, efficiency may be higher.

But the basic rules stay the same

1) It is better to use a smaller motor if possible and have full load rather than partial over the driving cycle. This seems more important than the type of motor.

2) You do not to have to worry about aerodynamics until speeds exceeds 70 km/h assumed that you are not driving in heavy wind. Tires are more important at the normal driving cycle.

3) OEM-data is not more reliable than your own test under your condition.


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## Duncan (Dec 8, 2008)

Hi Gunnarths
I have a couple of issues with your comment

"Permanent-magnet motors ruled (in all OEM)"
Tesla, Nissan use induction motors - NOT permanent magnet!


2) You do not to have to worry about aerodynamics until speeds exceeds 70 km/h assumed that you are not driving in heavy wind. Tires are more important at the normal driving cycle.

NO - Aerodynamics are important even down at 30 or 40 Kph and tires are not that important - inflation pressure makes more difference than the type of tire although saying that most cars these days have tires that are far too wide - this is for the looks rather than performance


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## Karter2 (Nov 17, 2011)

Hey Duncan,
I think you should read that comment of Gunnarhs about motors again....


> ....
> ....* Low speed / Partial load efficiency*: Permanent-magnet motors ruled (in all OEM)
> High Speed / Full load efficiency : Induction motors ruled.
> Normal (brushed) DC drives were better than expected but still inferior
> Overall best performance (besides Tesla) surprise surprise, the DC Sep Ex-Motor - drive !!!


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## Duncan (Dec 8, 2008)

Hi Karter
I know you guys use American English rather than the real thing but 

"*Low speed / Partial load efficiency*: Permanent-magnet motors ruled (in all OEM)"

Says that at low speed in all OEM permanent magnet motors rule

This requires that all OEM use permanent magnet motors 

And they don't!!!

The mass production EV's (Leaf and Tesla) use induction motors

The key term is "All"


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## gunnarhs (Apr 24, 2012)

Duncan said:


> Hi Gunnarths
> I have a couple of issues with your comment
> 
> "Permanent-magnet motors ruled (in all OEM)"
> ...



1) I hope I did not accidentally qualify Tesla as OEM , they use of course Induction motor. 
Nissan Leaf 2011 uses Permanent Magnet Motor (or synchronous), they do not use (asynchronous)Induction motor. I can not see that this has changed in newer versions.
VW, Audi,BMW, Citroen,Mitsubishi use all (different types) of PM-motors.

2) Mentioning importance of tires I was not meaning only the type but also the tire mass, pressure and condition of course. 
When calculating the effect on consumption you have 3 force factors to consider, acceleration, rolling resistance and drag force.
If you just look at rolling resistance and drag force which is the force you need to keep the car at same speed , for a standard small car they are about equal up to 40 km/h, then the drag force takes over.
But in real driving , acceleration is the really important factor as car is beeing accelerated up to the final driving speed, especially in urban traffic. So the main force there is Mass X Acceleration until final speed is reached. 
As you can calculate for a 1000 kg car with (only) 2m/s*s acceleration the force used is quite dominant.
So for urban traffic, and personal car weight is most important and in start stop traffic rolling resistance becomes secondary. Ask BMW about their i3


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## gunnarhs (Apr 24, 2012)

Duncan said:


> Hi Karter
> I know you guys use American English rather than the real thing but
> 
> "*Low speed / Partial load efficiency*: Permanent-magnet motors ruled (in all OEM)"
> ...


Yes sorry, I meant of course all tested OEM (mentioned Mitsubishi, Nissan 2011, Tesla is no OEM in my opinion), I could have been clearer.

Nissan motor (at least 2011) has permanent magnets see
http://www.sciencedirect.com/science/article/pii/S2214993715000032


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## miscrms (Sep 25, 2013)

I think its important to recognize that rules of thumb for the weight / drag crossover speeds are going to be related to the ratio of weight to CdA of the vehicle type. So rules of thumb for cars may not hold true for other vehicle types. For example a bicycle, which has a much different weight to CdA profile, can cross over as low as 10-15km/h.

Rob


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## gunnarhs (Apr 24, 2012)

miscrms said:


> I think its important to recognize that rules of thumb for the weight / drag crossover speeds are going to be related to the ratio of weight to CdA of the vehicle type. So rules of thumb for cars may not hold true for other vehicle types. For example a bicycle, which has a much different weight to CdA profile, can cross over as low as 10-15km/h.
> 
> Rob


Yes that is true I may have been too focused on standard cars 
So for the kart mentioned here in the thread is probably more dependant on the drag force


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## Karter2 (Nov 17, 2011)

Not necessarily..
The kart (terrible choice for an EV) would have a poor drag coef, but a very small frontal area.
However with 20 kWhr of battery , motor, and driver etc onboard , it will be very heavy for its size (300-400kg ?), and with those small wheels. So Rolling resistance may well be the major consideration.


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## Duncan (Dec 8, 2008)

Tesla is not an OEM??

What is required for Tesla to qualify?


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## gunnarhs (Apr 24, 2012)

Duncan said:


> Tesla is not an OEM??
> 
> What is required for Tesla to qualify?


That they produce only about 20% for themselves and 80% for other Automobile-Manufactures . 
This would of course result them buying more from others too.

As defined:
"Original Equipment Manufacturer (OEM) is a company that makes a part or subsystem that is used in *another * company's end product."

But Tesla is really trying to be an OEM and Mercedes Benz and Toyota have used their stuff, at least for prototype or small series car. 
Actually it was a big part of Teslas original business-plan to supply other companies...


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## Karter2 (Nov 17, 2011)

Wow !
..where did that definition of OEM come from ?


> OEM stands for Original Equipment Manufacturer. The OEM is the original producer of a vehicle's components,
> 
> Read more: What is an Original Equipment Manufacturer (OEM) in the automotive sector? | Investopedia http://www.investopedia.com/ask/ans...turer-oem-automotive-sector.asp#ixzz43jOYbYlI


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## ishiwgao (May 5, 2011)

gunnarhs said:


> That they produce only about 20% for themselves and 80% for other Automobile-Manufactures .
> This would of course result them buying more from others too.
> 
> As defined:
> "Original Equipment Manufacturer (OEM) is a company that makes a part or subsystem that is used in *another * company's end product."


This i want to know too. where did this definition come from?


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## runcyclexcski (Mar 21, 2016)

Hi all,

Amazing responses, thank you so much for your time! I loved the numbers, too: being a scientist, it matters a lot. 

Regarding performance at low temperatures -- this something I've always been wondering about myself! As as biochemist, I know well that chemistry and biology need warmths, preferentially, 37C . Are there many Teslas in Norway? I guess one could funnel some of the unused energy (i.e. heat) to warm up the pack. Is this what Tesla does? I am in the UK... cold by California standards, warm by Norwegian standards. 

Regarding karts -- I can re-consider, it's just I wanted to start with something cheap, off-the-shelf which is known to work OK-ish at high speeds. Probably, for the most aerodynamic shape/shell, the frame would need to be made from scratch. I know CAD, and I know programming; there is a C++ package (MEEP?) could use, should take a week to learn. Making a shell: I would do it like they do for canoes and kayaks. And yes, as you may guess, I do not care if it looks odd. What we have on the road now are mostly steel bricks, mostly with empty space inside, and to me that is odd. One may say it's been done for years, and my answer is that it only could be done with the availability of cheap oil. In summary, 1-seater and a boat tail, sounds good to me. Probably, a 3-wheeler.

Regarding velomobiles -- I used to race bicycles, and I've been researching velomobiles on and off for years. I concluded that the field is very small, it mostly is run by amateurs and enthusiasts, there are not many publications, and they seem to be very much at early stages... My decision was that it's easier to start with a car (even if it's a kart), and make it smaller and lighter, than to take a bicycle and make it go faster and become more stable and safe. Reason being that billions (?) of cars have been sold, and design points and safety have been worked out for 100+ years. The market for velomobiles is essentially non-existent. Besides, the cost of a velomobile is 2x that of a full self-contained street-legal go-kart! BTW, do take a look at the F170 if you haven't, it's not as small and useless as a racing go kart...

Regarding the Chinese LiPo batteries, I understand your scepticism. LiPo is lighter than Li-Ion (not 10x lighter, of course, more like 1.5x lighter). I currently have several 10,000 mAh 5V packs from the same company that went through 50 cycles, each weights about 1/2 lb, and they have lived up to the specs (I did the measurements). At 1/2 lb per 50 Wh... a 10kW-hr battery thus would be 200x heavier, or 100 lbs, which is lighter than the Leaf pack, and does not violate the laws of physics. Of course, the Leaf pack has other things in it that may be required for performance, not just the cells. Water cooling? 

the perspective of soldering together 200 battery packs does not make me jump with excitement. So, it might be easier just to get a Leaf pack and be done with it... but it's darn heavy!


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## runcyclexcski (Mar 21, 2016)

Duncan said:


> Hi Gunnarths
> I have a couple of issues with your comment
> 
> "Permanent-magnet motors ruled (in all OEM)"
> ...


Yes, for bicycle racing, at 25+ mph you mostly push the wind out. Drafting starts to matter above 20+ mph.


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## gunnarhs (Apr 24, 2012)

Karter2 said:


> Wow !
> ..where did that definition of OEM come from ?





ishiwgao said:


> This i want to know too. where did this definition come from?


Well I took it from the source the big WIKI which never lies:
https://en.wikipedia.org/wiki/Original_equipment_manufacturer

Karters link does also give a good explanation, but the key is that to call your OEM you are a part of a supply chain, at least in the world I know

But I will add some explanation and example of different types OEM.

1) Automobile manufacturer OEM
Renault, Peugeot and Citroen Produce components, starting from head-lights up to the motor which they sell to other manufacturers under OEM-condtion.
This means that for example when Peugeot sells motors for a production line of BMW, Peugeot guarantees the quality and endurance of the motor (for certain time, condition etc).
So if the Peugeot - motor in the BMW car breaks down and car/motor is still under gurantee, BMW sends the bill to Peugeot.

2) 3rd party OEM
Bosch, Infineon etc. which produce components like Airbag-system, Central-Door locks , Fuel - control Systems etc for different type of cars (but not cars themselves)
The same applies here, the 3-rd-party product undergoes quality tests regarding the prototype ( at TUV for example) and the production line (ISO XXXX) which should ensure the basic types functionality, reliability and OEM-qualification.
Additional changes made by the manufacturer buying the product changes the label of the product but still leaves the core responsibility to the third-party OEM.
So failures in the hardware of fuel-control-system or airbag-computer must be covered by third party OEM.
If there have been made additional changes by the buying party (usually Automobile manufacturer or other 3d-party) 
for example in Software (common in Airbag-systems and Fuel control-systems) the party which changed the Software becomes responsible for that part.
Volkswagen using Bosch-Fuel-control system is a good example where Software was changed.
Peugeot using Infineon Air-bag system and adapting Software to different car types (4-door, 5 - door etc) an another.

Other producer which produce aftermarket products (not under OEM-licence) which are often used for cheap spare parts are not OEM-parties.
(CE = Chinese export  , not more to say)

So the question about Tesla is this

1) Tesla as supplier: Does Mercedes / Toyota or Tesla pay if the Tesla electric drive fails under guarantee . Last time I knew (from Mercedes source) not Tesla
2) Tesla as buyer: If the Single-speed transmission originally made by Borg Warner fails under guarantee, who does pay, Borg Warner or Tesla. ? I have heard two different things about that 
The only open drive I have seen did not have a Borg Warner production line number or anything relating to Borg Warner, but it was not from the S-Type...
3) Does Tesla go through OEM - certificate process for each component they produce? Probably....And can we buy it?


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## runcyclexcski (Mar 21, 2016)

Regarding the weight of the battery and the weight of my mythical self-biuld one-seater nano-EV. 

According to the Wikipedia, model S's 80 kWh battery weights 1200 lb. Assuming that my narrow, low, light, streamlined one-seater could run for the same range on a 10 kWh battery of Tesla-like design (Tesla does not sell such batteries), the battery would weigh 8-fold less, or 150 lb. This is 2x better in terms of energy density than the Leaf battery, so the Leaf battery is a non-starter, and I am abandoning that idea for now.

I weigh almost 200 lb (fat), plus 150 lb for the battery, plus another 100 lb for the wheels, motor, controller, shell, and the frame. We get 450 lb total. Coincidentally, this is almost exactly 10-fold less than the Tesla (4,647 lb according to the Wiki). So my math cannot be that far off. 

With a self-built LiPo battery, I could shave off 50 lbs, probably, but not sure if it's worth the trouble.

In sum, if I could find a reliable off-the-shelf pack of Tesla-like design at 10kWh, I would be willing to pay for that, rather than fiddling with welding hundreds of cells together and setting something on fire. The Tesla 85kWh pack costs $40K. Thus at 10kWh one COULD cost $5K, which is not outlandish at all. Add 2K for self-building the rest, and we have a $7K DIY EV with Tesla-like range... potentially... at 10% cost.


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## BWA (Mar 14, 2015)

"plus another 100 lb for the wheels, motor, controller, shell, and the frame"

I think you are being hugely optimistic here, by a factor of at least 4, probably closer to 5.

My very modest power AC24Ls, weighs about 90 pounds. I expect the Inverter to weigh 40 pounds.

If you could build a fully enclosed vehicle capable of carrying 200 pounds of driver and, 150 pounds of batteries that weighed much less than 800 pounds bare, I would be very surprised.

Headlights, tail lights, signals, switches, wiring harness, even before you count the EV specific stuff is going to weigh 50-60 pounds..... Seats are going to be 40-60 pounds each......

Stuff weighs, there's no getting around it


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## runcyclexcski (Mar 21, 2016)

Stuff does weigh, the question is -- how much does it weigh? 

AC24L that weights 90 lbs... i googled it, looks like an old-school motor? 

http://manualmachine.com/global-machinery-company/ac24l/933333-user-manual/

Indeed, I have plenty of vacuum pump DC motors lying around at the lab, they are indeed heavy, low-power, and ugly. I have recently replaced a 250W one that weighed 10 pounds with an outrunner brushless motor that weighed 1/10 of that.

So, with research, I think I can do better than a 90-pound motor. A google search of "10 kW outrunner motor" produced this (below), which specs at 2.9 kilos, i.e. at 6 pounds. 

http://alienpowersystem.com/shop/brushless-motors/12090-outrunner-brushless-motor-130kv-15000w/

If I accept that outrunner brushless motors used in drones are not practical in cars, here is a more 'traditional' design motor rated at 10 kW continuous power, 35 kW peak. Weight: 35 pounds, cost: under $1000. 

http://www.thunderstruck-ev.com/motenergy-brushless-ii-pmac-me0913.html

Solar racing cars seem to be frequently using this particular type of motor that costs 20K and weighs 40 lb: NuGen Mobility SC-M150-08 Axial Flux. Not sure what is 'New Generation' about it, except that it's in-wheel, i.e. easy to mount/plug and play. Fine, Stanford kids can afford it, I think I will pass. Again, 40 lb is much less than 90 lbs, may be the 35-40 lb figure is the most realistic one for a reliable motor, and everything else will be dodgy/self destructive. 

http://www.ngmcorp.com/Products.htm

Here is a link to GA tech solar car specs which also sites this motor:

http://www2.ece.gatech.edu/academic...ll/ECE4007L01/ws3/SJMC - Proposal Final-4.pdf


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## runcyclexcski (Mar 21, 2016)

As for the seats... the chair I am sitting on right now weighs 3 lbs, why do I need a 50 lb seat?


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## Karter2 (Nov 17, 2011)

runcyclexcski said:


> ...... model S's 80 kWh battery weights 1200 lb. Assuming that my narrow, low, light, streamlined one-seater could run for the same range on a 10 kWh battery of Tesla-like design (Tesla does not sell such batteries), the battery would weigh 8-fold less, or 150 lb. This is 2x better in terms of energy density than the Leaf battery, so the Leaf battery is a non-starter, and I am abandoning that idea for now.....
> .


So, now you expect your EV to go 300miles on 10kWhr ? 
FYI you can buy salvaged Tesla "modules" ..22v, 200Ahr, 4.5 KWhr, for around $1200. Each module weighs< 30kg.
Leaf "modules" are 7.4 v, 60Ahr , 450Whr and cost $80-120 , or cheaper in volume. Because of their size/voltage/capacity, they are more flexible to assemble a pack from.


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## dcb (Dec 5, 2009)

Karter2 said:


> Tesla's range is simply the result of using the largest capacity


Mostly true, but they definitely thought about aero with a fairly low cd of .24 (sorry I don't have the frontal area handy, but it matters)

http://ecomento.com/2014/05/30/slippery-tesla-model-s-triumphs-in-wind-tunnel-shootout/


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## runcyclexcski (Mar 21, 2016)

Karter2 said:


> So, now you expect your EV to go 300miles on 10kWhr ?
> FYI you can buy salvaged Tesla "modules" ..22v, 200Ahr, 4.5 KWhr, for around $1200. Each module weighs< 30kg.
> Leaf "modules" are 7.4 v, 60Ahr , 450Whr and cost $80-120 , or cheaper in volume. Because of their size/voltage/capacity, they are more flexible to assemble a pack from.


Thank you for the hint! May I ask who sells those salvaged Tesla modules? I bet there are not many Teslas at junk yards (unlike Fiestas -- lucky me with my current ride). 

Going as far as a Tesla on 10 kWh -- I see why not, if the total weight was 10x less than Tesla, the frontal area was 2+ x smaller than Tesla, and the cd was as good, or better than Tesla (if we use Aptera's claimed cd of .15).


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## Karter2 (Nov 17, 2011)

..why not ?
Because your weight is not going to be 10x less
Your resistances ..drag, Rolling, etc...wont be 10x less
Your power consumption wont be 10x less

Be realistic about weights, aero etc , and find yourself a decent simulator program to run.
Then calculate your battery needs.


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## gunnarhs (Apr 24, 2012)

runcyclexcski said:


> Thank you for the hint! May I ask who sells those salvaged Tesla modules? I bet there are not many Teslas at junk yards (unlike Fiestas -- lucky me with my current ride).
> 
> Going as far as a Tesla on 10 kWh -- I see why not, if the total weight was 10x less than Tesla, the frontal area was 2+ x smaller than Tesla, and the cd was as good, or better than Tesla (if we use Aptera's claimed cd of .15).


I hope you have read Karters points in last post, unless you have unlimited budget and resources you will not beat or even reach Teslas km/kWh/kg ratio. So trying to scale down 10 times alone will not do the job.

The only thing where I see a small vehicle having real advantage over Tesla is by using aircooling only which is possible at lower power stages.
It is ofcourse possible to use LiPo batteries instead of normal Li but you will definatley not reach 3000 cycles with them. You can also build Chassis and even more on Carbon - fiber but that is quite expensive.

To answer a previous question on that point, yes in Norway there are a lot of Teslas and Electric cars in general and they are doing well. Range is lower than published , most due to lover average temperature, but local dealers are cool and tell you the real local range before you buy so no problem there. When using forced cooling/ heating like Tesla does on whole drivetrain it will in average drain about 5-10% of your battery pack.


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## Duncan (Dec 8, 2008)

To the comments about 1/10th the weight

It is not as unattainable as you might imagine - as you reduce the weight you can get into a feedback process
Lower weight means that you can use lower weight parts which lowers the weight...and so on

If I was going that way I would be starting with bike parts - the Human Powered Vehicle one hour speed record is over 80Kph - with a human power of about 400 watts.

Such a vehicle would require about 5Watthours/Km, 8watthrs/mile and a 1kwhr pack should take it 100 miles


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## rmay635703 (Oct 23, 2008)

Leaving out certain outliers, the longest range DIY EVs are mostly 3 or 4 wheel variations of the original 
Honda Insight (one is rather famous though incomplete, the 3 wheel Dolphin car and the "other" guy with a mostly stock 00 insight with EV drivetrain both get under 160wt/mile at highway speeds)
A lesser known conversion is a 1970 Subaru 360 that occasionally pops up on another forum I visit, his Subaru, although not driven fast is under 100wthr / mile, which is generally not possible to achieve in a normal weight car (weight does matter when its 900lbs going 30mph, with minimal frontal area)

Then we have the exotics, there is one car that shows up at the MREA, I usually think of it as the Bat car, the guy is fixated on 4 wheel steering for god knows what reason.
He is streamlined and has good range and efficiency, despite his desire to make unreasonable systems.

There have been a handfull of I stuffed a vehicle with batteries examples but they aren't really normal DIY cars and cost significantly more than an off the shelf car.
(aka I won't mention them here because to me they aren't worth mentioning)

Ah Well


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## runcyclexcski (Mar 21, 2016)

gunnarhs said:


> The only thing where I see a small vehicle having real advantage over Tesla is by using aircooling only which is possible at lower power stages.
> It is ofcourse possible to use LiPo batteries instead of normal Li but you will definatley not reach 3000 cycles with them. You can also build Chassis and even more on Carbon - fiber but that is quite expensive.
> 
> .


I see, the point about 3,000 cycles is a good one, I did not know that LiPos had so much less cycles in them than LiOn. So I will, for now, presume that I will have to use tested packs... hopefully I can get my hands on 1-2 Tesla modules.

I have not thought much yet about the need for cooling, will continue to read on. But... a fan or a water cooler is not rocket science?

Regarding the 10x reduction of weight not_possible/not_sufficient -- I think I could try to strike a balance between a TESLA and an HPV/hypermileage "cars" mentioned in the thread (the latter should be could bicycles, actually). I think you will agree that HPVs weigh more like 50x less than a TESLA (an 80 lb bicycle is beast, mine weighs 15 lb). And even though the HPVs are useless for real trips/commuting, some of their design principles could be adapted. After all, HPVs are aimed at propelling a vehicle at 200-400W at 40 mph, although 400 W is sustainable for not more than 1 hr by cat 2 riders... I know from experience  ). That's at a cost of having to lie down... to me it's not a big cost. Coming from the HPV field, a 5kW motor is a *major* boost in power, and solar vehicles, coincidentally, use that kind of motor power.

Regarding time, money, and resources... 

Time: As DIYers, our main resource is time -- wouldn't you agree? Some people choose to invest their time to watch Game of Thrones or play videogames. We believe our time is better spent making something we find useful and interesting (and occasionally to post lengthy messages). If one works 50 days a year (one whole day a weekend), 8 hrs a day comes up to 400 hrs. A skilled worker at a factory wants to be paid $100 an hour (I think those days are over, but it's for arguments' sake). Thus, 400 hrs is equivalent $40,000. That's half the cost of a TESLA. I am not mentioning million dollar salaries of CEOs.

Resources/skills: I design and build single-molecule imaging instruments for a living, so I am OK with milling, indicating, lathing, etc. I am also OK at figuring out what can be done on the cheap by myself, and what must be outsourced. E.g. we just built a $0.6 mln microscope (if bought commercially) for $0.2 mln, which, on top of being cheaper and better, can be customized and serviced at no cost.

Money: I have time (see above), so spending 10-15K on the course of 2-3 years is not as bad as shelving it out at once. Most people probably waste that much in 3 years on going out/restaurants/cable TV/fancy hotels.


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## runcyclexcski (Mar 21, 2016)

Duncan said:


> As you reduce the weight you can get into a feedback process
> Lower weight means that you can use lower weight parts which lowers the weight...and so on
> 
> If I was going that way I would be starting with bike parts - the Human Powered Vehicle one hour speed record is over 80Kph - with a human power of about 400 watts.
> ...


Yes, bike parts will be used, or at least Ti hardware which can be bought from bike shops...

1kwhr pack for 100 miles would be great, but I would prefer not to be lying head first and not to be sealed inside with duct tape by a team of grad students each time I go on a trip  So... I can settle 200 miles on a 10kW pack for comfort. Of course, comfort is a relative thing. Apparently, to some, being comfortable requires a seat that weighs 50 pounds...


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## runcyclexcski (Mar 21, 2016)

Dolphin car -- looks interesting. Again, some design ideas could be borrowed.

http://www.vortexplans.com/

The dude wants $90 for plans, huh? If I manage to get my idea to work, I will make it all open source... similar to Wikispeed


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## samwichse (Jan 28, 2012)

I've heard good things from people who've built a tri Magnum:

http://rqriley.com/tri-mag.html

(Also about $90)


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## runcyclexcski (Mar 21, 2016)

I remember seeing this! Probably will order their plans -- to borrow ideas from. Like the 80-s looking pictures. Just curious -- are they really making any money for $90 anyway? This was my thought behind open-source: I have a job, so why charge money for something that won't make me rich enough to quit my job? Ideas are for spreading.


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## Duncan (Dec 8, 2008)

I had a quick look at the plans - and a google showed a webpage "dummies guide" with the guy building one of these

IMHO it's horrible - it's made of plywood and will weigh an absolute ton!

Have a look at this technique instead

http://www.autospeed.com/cms/A_112925/article.html


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## gunnarhs (Apr 24, 2012)

Duncan said:


> Have a look at this technique instead
> 
> http://www.autospeed.com/cms/A_112925/article.html


Nice!! This approach could for sure save a lot of money, and looks very promising for this thread requirements.

I have seen 60.000+ Euros spent in efforts not resulting a driving prototype in University Electric Car projects, usually most the money gets spent on the first stages, which this aproach could avoid.


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## runcyclexcski (Mar 21, 2016)

Well, even if it did not produce a working prototype, it produced knowledge which can be used by others, and ideas that did not work for them may be re-examined by others. I have a few aircraft structural honeycomb panels lying around at the shap, glad to see that they may have some use...


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## karmann eclectric (Mar 26, 2008)

For a true long range DIY EV that squeezes pennies and watt-hours like nobody else, check out my friend Dave Cloud's Dolphin. 
http://www.treehugger.com/cars/dave-clouds-214-mpg-geo-metro-aka-the-dolphin.html
It's not some janky plywood box, but a Geo Metro transformed into a streamliner with the only exotic ingredient being Boeing Surplus honeycomb, and it made its first 100 mile run with handpicked lead SLI battery cores from a local wholesaler. That's right- used-up 12V car starting batteries! 
With Lithium, Dave's Dolphin could do astounding things, but he built it to prove a point about good old lead. Dave only does things Dave's way. There's lots of other links if you google for it.
http://ecomodder.com/blog/dave-clouds-super-aerodynamic-electric-car-dolphin/?pid=143


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## rmay635703 (Oct 23, 2008)

I mentioned the Dolphin car on the last page, people fail to understand that range is 100% aero, RR at highway speeds is almost meaningless.
Its sad that we don't sell the whole enchalada, like a Dolphin car.

Lb for lb wood is stronger than steel but requires more room and is less formable.

To this day there are standards for automotive wood based construction recognized in the US.

I see no reason why a wooden extension could not be moderately light and structurally solid, many wooden and cloth airplanes are strong and light compared to metal, same techniques apply I suppose.


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## Karter2 (Nov 17, 2011)

runcyclexcski said:


> Well, even if it did not produce a working prototype, it produced knowledge which can be used by others, and ideas that did not work for them may be re-examined by others. I have a few aircraft structural honeycomb panels lying around at the shap, glad to see that they may have some use...


..? If you are refering to the Al huneycomb car built by the Uni students,.. Called. "Trev",......It certainly did produce a working prototype that went on to drive across Australia...
http://w3.unisa.edu.au/solarcar/Trev/default.asp
Personally, i still think this is one of the best DIY EV's built,....and that was over 10 years ago !












> Staff and students at the University of South Australia have designed and built such a car—Trev. Its features include:
> 
> two comfortable seats, since more than 90% of urban trips have only one or two people in the car;
> enough luggage space for at least two overnight bags;
> ...


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## mjcrow (Jan 5, 2008)

Actually "Trev" went on and drove around the world http://www.zero-race.com/
It is a great little vehicle, a number of members of our local AEVA (Australian Electric Vehicle Association) were involved in driving legs of the zero race, and Trev proved to be a very capable and quite reliable, little car.


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## Karter2 (Nov 17, 2011)

Ahh, yes i forgot about that little trip !
There are a lot of good learnings in this fedback from the Trev build..
http://scg.ml.unisa.edu.au/Trev_lessons.pdf


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## runcyclexcski (Mar 21, 2016)

The Trev is indeed quite amazing. I wonder how street-legal it was during its trip around the world (particularly in Europe and the US), or if the got some kind of exempt status.


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## miscrms (Sep 25, 2013)

Don't know about everywhere, but to my knowledge in the US custom / homebuilt, kitcars, and sometimes even small volume production (through a more formal process) are usually exempt from most requirements. They just have to comply with the basics, like turn signals, brake lights, headlights, speedometer, etc.


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## sjd.aliyan (Jan 17, 2018)

Longest range for all kind of evs is 1600km beaten by Eric Lundgren.
He used only recycled materials from tesla


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## Kevin Sharpe (Jul 4, 2011)

sjd.aliyan said:


> He used only recycled materials from tesla


No Tesla parts were used in the car... see here for a few more technical details;


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## Matej (Dec 4, 2015)

Kevin Sharpe said:


> No Tesla parts were used in the car... see here for a few more technical details;


What batteries are those? EnerDel?


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## sjd.aliyan (Jan 17, 2018)

Matej said:


> What batteries are those? EnerDel?


Tesla's?Panasonic made 3400 mAh 18650 cells.
Eric's? i'm not sure.


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## Matej (Dec 4, 2015)

sjd.aliyan said:


> Tesla's?Panasonic made 3400 mAh 18650 cells.
> Eric's? i'm not sure.


The ones in the silver BMW. They state that it is built from spare parts, but I do not know of any EV or hybrid batteries that look like that.


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