# Tesla Roadster Replacement



## njloof (Nov 21, 2011)

This one, perhaps?

http://www.rimac-automobili.com/


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## Kevin Sharpe (Jul 4, 2011)

njloof said:


> This one, perhaps?


last time I heard that was $900K and I know I can do more for less


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## Ziggythewiz (May 16, 2010)

It's certainly doable but your requirements make for a difficult DIY. You can get all the power you want from Warp 9s or 11s, I've heard of up to 4 used in series...but you want regen, so you're stuck with whatever AC motors are out there. Maybe you could get 3 or 4 of HPEVs new stuff...

The other issue is range. It's difficult to get over 100 miles with DIY EV batteries in a small car. Tesla had to use thousands of laptop cells, which you can cram anywhere.


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## major (Apr 4, 2008)

Kevin Sharpe said:


> last time I heard that was $900K and I know I can do more for less


Get a Tesla model S, gut the propulsion system (motor, controller and battery) and stick in the platform of your choice.


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## Kevin Sharpe (Jul 4, 2011)

major said:


> Get a Tesla model S, gut the propulsion system (motor, controller and battery) and stick in the platform of your choice.


It won't hit the desired performance figures... also the battery is the floor so refitting to another platform would be tough 

We have considered using a crashed Roadster as a starting point... using the latest panasonic cells would deliver the range.


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## major (Apr 4, 2008)

Kevin Sharpe said:


> It won't hit the desired performance figures... also the battery is the floor so refitting to another platform would be tough
> 
> We have considered using a crashed Roadster as a starting point... using the latest panasonic cells would deliver the range.


I read the performance package S motor at 416 hp. That is well above the Roadster motor. And I figured you'd need to modify things like the battery package.


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## Nuts&Volts (Dec 20, 2011)

Contact EIG and buy a ton of their batteries. Easier to package than thousands of the panasonic cells. Then buy a EVO Electric AFM230. Mate that to a Sevcon Gen4 Size10.

Make a 800V 40-50kWh pack that can do 400kW with a motor and controller that can do close to 300kW. This will probably cost close to $25-30k for the controller/motor and then $40-50k for the battery. Then maybe $20-30k more for materials and fab work. Charger would be another $3-10k 

Put all that in some sweet ass sports car and you're good to go. I would think you could get about 200 miles out of a pack that big when you aren't riding it hard. Your talking like 800 lbs in batteries and 160lbs in motor/controller. So your car may be quick heavy. 

This is probably the route I would go, but with 30kWh or so. That is if I had $100k to spend on something. Actually I would go with 2 hub motors, 30kWh, and try to weight down to 2500lbs or something.


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## Nuts&Volts (Dec 20, 2011)

major said:


> I read the performance package S motor at 416 hp. That is well above the Roadster motor. And I figured you'd need to modify things like the battery package.


Battery is in the floor, but the modules could be reconfigured and maybe even possible to just repackage every system in the Model S... You could use the entire rear axle (motor/controller) in some new sports car. Lot of fab work, but it is possible.


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## rochesterricer (Jan 5, 2011)

Kevin Sharpe said:


> It won't hit the desired performance figures... also the battery is the floor so refitting to another platform would be tough
> 
> We have considered using a crashed Roadster as a starting point... using the latest panasonic cells would deliver the range.


The battery is in the floor, but it should be fairly easily removed. According to Elon Musk, the battery is designed to be replaced in minutes at a battery quick change station. They are supposed to make some announcement about what they plan to do with this capability sometime this year. 

However, keeping the battery intact might require you to at least use a car with the same wheelbase as the Model S. It is probably possible to take the battery apart and rearrange the modules, if you have the patience(I don't know how many modules make up the battery).


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## Bowser330 (Jun 15, 2008)

Kevin Sharpe said:


> I've driven my Tesla Roadster 32,000 miles all over Europe in the past couple of years and have enjoyed every single mile
> 
> I'm ready for my next EV and intend it to outperform the Roadster. I would be interested in members views on achieving the following in a 2 seat sports car;
> 
> ...


Your demands aren't hard to achieve but you left out your budget....lets assume its 100K USD (about as much as the Tesla Roadster)

There are several companies now that offer high end AC or BLDC drive systems and/or components. Check out a few of them below:

http://www.evo-electric.com/inc/files/AFM-140-Spec-Sheet-V1.1.pdf
http://www.rinehartmotion.com/products.html (PM150DZ)
http://www.vaxosystems.com/store/default.aspx
http://www.evdrive.com/

A dual drive/AWD setup (~40K$) should meet your acceleration and top speed needs. They have regen and also great efficiency so that should help towards your 150mile goal, which is primarily dependent on your batteries.

For batteries your best bet is the A123 20AH pouch cells. 500g each.
200series 3parallel = 600 cells = 660lb pack. 30$ each to your door = 18,000$ total (not including cost to test, build, and protect the pack)
660V nom. * 60AH = ~40kwh, which is 150 mile range if you drive it to 100% empty and average 267wh/mile while doing it.

So total with the three most expensive components is $58,000 USD

Only thing left to do is choose a donor you like....

Note: Keep in mind if you were willing to forgo Regen and use a DC system with a shift or two you could obtain the same acceleration goals for ~38K$ or 20K$ cheaper.


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## skooler (Mar 26, 2011)

Hi Kevin,

I'm not too far from you.

Just want to say that your doing a great job, we have one of your donated chargestations at work!

What is it you are actually trying to achieve with this car? I don't mean performance figures but is it publicity, a personal runaround?

I have been looking into a high performance build in collaboration with a few UK companies. Perhaps it'd be worth having a chat?

Cheers,

Mike


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## Stiive (Nov 22, 2008)

Kevin Sharpe said:


> We have considered using a crashed Roadster as a starting point... using the latest panasonic cells would deliver the range.


Use the crashed roadster's motor, 200kW+ can easily give you <3sec in a light enough car. But then again, why not just use the crashed roadsters controller and batteries as well? Heck, why you even getting rid of your roadster?


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## Kevin Sharpe (Jul 4, 2011)

Nuts&Volts said:


> Contact EIG and buy a ton of their batteries. Easier to package than thousands of the panasonic cells. Then buy a EVO Electric AFM230. Mate that to a Sevcon Gen4 Size10.


Many thanks... that looks really interesting, I will add that to the list


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## Kevin Sharpe (Jul 4, 2011)

Nuts&Volts said:


> You could use the entire rear axle (motor/controller) in some new sports car. Lot of fab work, but it is possible.


While that's all true, I think we would have more success with a Tesla Roadster donor (because a lot more information is in the public domain) or using off the shelf components from EV suppliers.


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## Kevin Sharpe (Jul 4, 2011)

Stiive said:


> Use the crashed roadster's motor, 200kW+ can easily give you <3sec in a light enough car. But then again, why not just use the crashed roadsters controller and batteries as well?


agreed... I think we could get a lot more out of the Roadster motor (including possibly liquid cooling) and replacing the cells with current chemistries would see a big improvement in performance. I also like the idea of splitting the Roadster battery in two.



Stiive said:


> Heck, why you even getting rid of your roadster?


I'm not... but I think we can achieve a lot more in 2012 than in 2007


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## Kevin Sharpe (Jul 4, 2011)

skooler said:


> What is it you are actually trying to achieve with this car? I don't mean performance figures but is it publicity, a personal runaround?


I undertake a lot of promo work for ZCW and other charities and the new car will be part of that activity. I also want to compete in more mainstream car events like Gumball 3000 and some of the trans-europe rally's. Today this is difficult with the current Roadster's range and charging rates.

I'm talking to several EV drag race and record attempt teams... very happy to talk more if you'd like to PM a number.


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## Kevin Sharpe (Jul 4, 2011)

Bowser330 said:


> Your demands aren't hard to achieve but you left out your budget....lets assume its 100K USD (about as much as the Tesla Roadster)


I left that out on purpose because I wanted to encourage people to blue sky this a little... I'm happy to spend money on things I care about and expected this spec to require something in the $100-$200K range.



Bowser330 said:


> Note: Keep in mind if you were willing to forgo Regen and use a DC system with a shift or two you could obtain the same acceleration goals for ~38K$ or 20K$ cheaper.


Regen is one of the things I love most about driving the Tesla Roadster and I'd be loathed to give that up 



Bowser330 said:


> Only thing left to do is choose a donor you like....


The Factory Five GTM is my current favourite... I'm talking to the European distributor about a RHD version


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## brainzel (Jun 15, 2009)

Do you want to build a car from sratch? With your own hands? Or should it be an existing company or builded car?


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## skooler (Mar 26, 2011)

Kevin Sharpe said:


> I undertake a lot of promo work for ZCW and other charities and the new car will be part of that activity. I also want to compete in more mainstream car events like Gumball 3000 and some of the trans-europe rally's. Today this is difficult with the current Roadster's range and charging rates.
> 
> I'm talking to several EV drag race and record attempt teams... very happy to talk more if you'd like to PM a number.


PM sent


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## adeyo (Jun 6, 2012)

See pm...sorry about the double post. I accidentally posted my pm


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## adeyo (Jun 6, 2012)

See pm....10 chars


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## Kevin Sharpe (Jul 4, 2011)

brainzel said:


> Do you want to build a car from sratch? With your own hands? Or should it be an existing company or builded car?


It's very unlikely that I will get the time to build this car from scratch. However, I have a computer hardware/software background and expect to do as much work as time allows.


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## Hollie Maea (Dec 9, 2009)

I would talk to Bob Simpson at evdrive. I met him a few weeks ago and he is very smart and energetic, and his drivetrain is very scalable and impressive if you have a little money to play with.


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## Kevin Sharpe (Jul 4, 2011)

Hollie Maea said:


> I would talk to Bob Simpson at evdrive. I met him a few weeks ago and he is very smart and energetic, and his drivetrain is very scalable and impressive if you have a little money to play with.


Many thanks... their initial response was to suggest we pay $6K for a pre-design study


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## Nuts&Volts (Dec 20, 2011)

Since you are wide open to things. Mission Motors probably makes one of the more power dense controllers on the market http://ridemission.com/. Their motors are ok, but not as good as others I have mentioned. Their battery packs are made with EIG cells and I think they are looking to use the newer 40Ah packs if premade packs is more your style. The panasonic are still the most energy dense cells in both volume and weight, but they lack some power capabilities.

On another note I am dreaming about putting 4 of these on a car someday. http://www.proteanelectric.com/. That is your motors and controllers all in wheel. Leaves the rest of your room for batteries, charger, electronics and cooling. Over 4000Nm peak at the wheel capable. That is awesome!

-Kyle


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## Ellrot (May 17, 2010)

njloof said:


> This one, perhaps?
> 
> http://www.rimac-automobili.com/


It's gotta be the Rimac if you got the cash


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## Kevin Sharpe (Jul 4, 2011)

Ellrot said:


> It's gotta be the Rimac if you got the cash


for $900K I can build a lot of car


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## rochesterricer (Jan 5, 2011)

Mate Rimac, username Crodriver on here, will sell you similar drivetrain components to what he is using in that car. It isn't cheap stuff, but it is very good. IIRC, he was able to get the BMW to run 11's with just one of those motors.


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## Kevin Sharpe (Jul 4, 2011)

Many thanks for all the feedback... I'm currently talking to a number of people about this project and will let you know how we get on 

Lots of rumours that Tesla will finally offer some performance upgrades for the Roadster including a sub 3 second 0-60 (not bad for a production car).


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## Dennis (Feb 25, 2008)

I would like to add that it is actually easier to obtain regen with a DC set up than with an AC setup, if the DC motor used is a sep EX. The people on here telling you that DC regen is not possible are assuming series wound DC motors. The only issues with a sep EX motor is you must know its field map and I do not know of any DC EV controller on the market in high power for such motors. In industrial manufacturing these controllers are common though, but require AC input because of using thyristors that are dependent on the AC sinewave to shut them off at the zero crossing.


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## drivin98 (May 9, 2008)

As previously suggested, I'd look into sourcing a motor/inverter from CroDriver (Rimac). He's put some of his stuff in an Opel Speedster already (http://www.facebook.com/photo.php?f...202.100003295904581.1189320210&type=1&theater), which is, of course, a close cousin of the Tesla Roadster.
Perhaps he might privately divulge what kind of performance he is getting with it.

Other thoughts: If Mission Motors will sell you two or more motors (AWD might be necessary to achieve that kind of acceleration without the benefit of slicks), using components like that might be more effective than trying to liquid cool a Tesla Roadster motor.
Also, you might consider an Ariel Atom or KTM X-Bow chassis (or similar) to trade off need for horsepower with weight reduction.
Similarly, you could even duplicate, or try to improve on, the Toyota Motorsport GMBH P001 that just won the electric class in the Pikes Peak International Hill Climb. (http://green.autoblog.com/2012/06/08/toyota-plans-radical-raid-on-pikes-peak-w-video/)


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## rochesterricer (Jan 5, 2011)

The Facebook link doesn't work for me.


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## MalcolmB (Jun 10, 2008)

Hi Kevin,
Just in case you haven't come across them before, I'd suggest looking at Yasa motors – they're built in Oxfordshire:
http://www.yasamotors.com/technology


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## CroDriver (Jan 8, 2009)

Kevin Sharpe said:


> for $900K I can build a lot of car


Really? Elon should hire you, you would save tons of R&D money.



> •Just three years ago, Tesla Motors was in big trouble. The company’s inaugural product—the $109,000 Tesla Roadster—was due to begin production in September 2007, but an internal audit done over the summer revealed that the cost to actually build the car had climbed to $140,000. It was a money-loser before a single unit had been delivered.​ •Musk was the lead investor but wasn’t running the company then, and he was taken aback by the state of affairs. He’d been led to believe that manufacturing the car would cost $65,000 and decided to investigate the discrepancy himself. He visited the body panel fabricator in England and discovered that the facility didn’t have the right tools to do the job. The car wasn’t just too expensive—as things stood, it couldn’t even be built.​ •*At this point, Musk and other investors had sunk nearly $100 million into the company and didn’t have a single car to show for it.* Martin Eberhard, CEO at the time and one of Tesla’s founders, was demoted and in a matter of months left the company. Michael Marks, an investor and former head of electronics maker Flextronics, stepped in as interim CEO.​


...and they "only" modified an existing car.

Honestly, it takes much more to develop a proper car. Of course you can make a car with that budget if you know what you're doing, but it can't be anywhere near a production car. There are thousands of details which need to be taken care of and that requires a skilled team and equipment (not cheap).


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## Kevin Sharpe (Jul 4, 2011)

CroDriver said:


> Honestly, it takes much more to develop a proper car.


I'm not going to get into an argument about the definition of a 'proper car'... all I will say about the Tesla Roadster is that it's an amazing car that I use everyday.

One option is to take a Tesla drivetrain and push it further.

We are looking at improved cooling for a Tesla motor. 3 Phase charging looks easy and obvious upgrade. Replacing the current 2400mah cells with the 3100mah used in the Model S would yield a 72kWh pack of the same weight as today's Roadster. This pack would deliver 250 miles even when I drive as fast as is possible on UK roads


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## Kevin Sharpe (Jul 4, 2011)

rochesterricer said:


> The Facebook link doesn't work for me.


nor for me


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## CroDriver (Jan 8, 2009)

Kevin Sharpe said:


> I'm not going to get into an argument about the definition of a 'proper car'... all I will say about the Tesla Roadster is that it's an amazing car that I use everyday.
> 
> One option is to take a Tesla drivetrain and push it further.
> 
> We are looking at improved cooling for a Tesla motor. 3 Phase charging looks easy and obvious upgrade. Replacing the current 2400mah cells with the 3100mah used in the Model S would yield a 72kWh pack of the same weight as today's Roadster. This pack would deliver 250 miles even when I drive as fast as is possible on UK roads


Reading through my post I realize I expressed myself wrong. I meant that it takes more than $900k to develop a car. I didn't mean that the Roadster is a bad car. I actually like it and think it was a huge achievement at the time they made it. 

Btw. Simply replacing cells won't work since the car's BMS/ECUs "think" the battery has 53 kWh. It won't allow you to use more than that since it wants to prevent a total discharge of the cells. You will need to hack into the ECUs or Tesla's assistance. I think it won't be easy to convince Tesla Motors to invest engineering resources into a one-off while they have tons of work for the future vehicles. 

It will also be hard to phisically replace the cells since Tesla uses a special method to connect the cells electrically - i.e. the connection is working as a fuse to protect the pack in case of single-cell failures.


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## Kevin Sharpe (Jul 4, 2011)

CroDriver said:


> I meant that it takes more than $900k to develop a car.


I think many of the projects here have developed cars for less than $900K 



CroDriver said:


> Btw. Simply replacing cells won't work since the car's BMS/ECUs "think" the battery has 53 kWh. It won't allow you to use more than that since it wants to prevent a total discharge of the cells. You will need to hack into the ECUs or Tesla's assistance.


I've designed many ASIC's and lots of computer hardware and software... I don't do this anymore but own several companies that do... obviously, we will have to get creative if we go down this route... it's just a problem to be solved.



CroDriver said:


> It will also be hard to phisically replace the cells since Tesla uses a special method to connect the cells electrically - i.e. the connection is working as a fuse to protect the pack in case of single-cell failures.


hard but not impossible


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## drivin98 (May 9, 2008)

Kevin Sharpe said:


> nor for me


Sorry, maybe you have to be Mate's Facebook friend to see it.

In any case, here's a video with it, taken when Mate graciously allowed a blind guy to drive it (so awesome, dude!).


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## aeroscott (Jan 5, 2008)

CroDriver said:


> Really? Elon should hire you, you would save tons of R&D money.
> 
> 
> 
> ...


Musk was a small investor (Eberhard wanted to keep control away from him) Musk(deep pockets) insisted on expencive changes ,lowering door sils , carbon body parts,etc,etc. Eberhard was in charge of finding a cfo , he says Musk stoped any of Eberhards atemps to get a cfo(cfo would unstand how Musk was overtaking Tesla)Soon Musk was thebigest investor/ owner, Eberhard the founder was out .; thats how the bigest cost overruns happened acording to Eberhard .


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## aeroscott (Jan 5, 2008)

Love the idea of a high end conversion . As I have said before 4 motor 4 wheel drive , ac, . but a 5th motor needs to be added with a powerfull fan that sucks air from under car and blows it forward for breaking /down force . Other directions for stability control . In full hard 4 motor regin huge amounts of power are generated ,the fan motor could use this if capable . Gas cooling (He or H ) would keep the heat more manageable . This is comon in utilty generators . My spell check needs to be downloaded !


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## aeroscott (Jan 5, 2008)

Switched reluctance motor seam to hold a advantage over sine wave ac in that they run on square wave( 10X less switching ), less heat in the rotor and full torque at start up. I would gas cool the controllers also. SR motors are more common in the EU.


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## Woodsmith (Jun 5, 2008)

Kevin Sharpe said:


> I think many of the projects here have developed cars for less than $900K


I think there may be a little misunderstanding here on both sides here.

There is a big difference between developing a production car from scratch and converting, or building, a one off using already developed parts and a bit of interesting engineering to make them work together.

I think CroDriver has done an incredible job with his car and look forward to its production sales.

Equally I am looking forward to your next car, given all the great work that you have achieved so far!


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## Kevin Sharpe (Jul 4, 2011)

Finally getting back to this project... we've been busy donating Charging Stations and now have more than 440 installed around the UK and a major international hotel chain about to announce a programme to install at all their locations 

I've also been working with two of the Formula E teams and in my 'spare' time reading lots more about EV technology, watching EVTV, developing OVMS and OCM, etc.

I'm probably going to use the experience of building my next-gen Roadster to help train up a group of young people and start a conversion company in the UK. I like Jack Rickard's approach to open EV components and will try to support that in the builds that we undertake. If anyone is interested in collaborating on any of this then please PM me.

With regards to the Roadster Project, anyone have any updated advice on component selection for our build?


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## skooler (Mar 26, 2011)

PM Sent


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## WarpedOne (Jun 26, 2009)

I have a proposition: It seems ever more unlikely Tesla Motors will spend their R&D on upgrading an old and discontinued product. Why don't you exercise your muscle and try to spec and produce 'an upgrade kit':
- new battery with modern top-of-the line cells - (maybe even 3 versions - same kWh at lower weight, some more kWh at a bit less weight, even more more kWh at same weight as now)
- beefed up PEM and motor cooling - higher sustained performance?
- some tweaks into brakes maybe
- you could look into AWD upgrade for the roadster. Front motor(s?) needn't be very strong, they would aid acceleration and strengthen regen through cornes.

I'm sure you'd get ton of exposure and even some business opportunity.


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## JRP3 (Mar 7, 2008)

Well they "crammed" them into one giant block, which you can do with any cells. The reason they went with those cells was because of cost and energy density.


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## Ziggythewiz (May 16, 2010)

JRP3 said:


> Well they "crammed" them into one giant block, which you can do with any cells.


...when you design the frame and body of the vehicle for that purpose.


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## Siwastaja (Aug 1, 2012)

+1 for AWD upgrade. It would be easiest to do as you could retain the old drive system as is and still get a lot more power. And this power would be very usable as the traction would get better. It would also make the regen even better.


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## Karter2 (Nov 17, 2011)

AWD just adds weight , cost , and efficiency losses.
Its not necessary for street performance ( eg Ferrari, Aston, Porche & Tesla have shown that). So unless you plan a World Rally attack, why bother.
Focus on refinement and range after performance is satisfied.


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## WarpedOne (Jun 26, 2009)

Not true.
AWD enables better dynamic control i.e. torque vectoring. It enables strong acceleration and stronger regen not only in straight line but also through curves etc.


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## Siwastaja (Aug 1, 2012)

Karter2 said:


> AWD just adds weight , cost , and efficiency losses.


True for an ICE car.

Electric is completely different. (Tesla offers two-motor AWD. Also see Rimac.)


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## JRP3 (Mar 7, 2008)

Well, unless the second motor weighs nothing, is free, and is 100% efficient, then it does indeed add weight, cost and efficiency losses. Also, Tesla does not yet offer a second motor option, though that is coming. Certainly AWD does have some advantages but unless you are frequently losing traction with 2 wheel drive then the advantages are probably minimal.


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## Siwastaja (Aug 1, 2012)

JRP3 said:


> Well, unless the second motor weighs nothing, is free, and is 100% efficient, then it does indeed add weight, cost and efficiency losses.


Please rethink and you may find the relatively simple error in what you just said, regarding all three points. (Three hints: 1) the original motor is not 100% efficient either. A bigger motor 2) weighs more and 3) costs more than a smaller motor.)

Still, it is true that AWD is a luxury thing in normal street use, but so is an even more powerful motor than in Tesla Roadster. But this topic was exactly about when the Tesla Roadster is not enough, and adding another motor might be easier than replacing the existing motor with a bigger one, and AWD could give more advantages instead of a single überbig motor (see http://www.rimac-automobili.com/ for motivation).

Always try to remember the context in these discussions.


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## JRP3 (Mar 7, 2008)

Siwastaja said:


> Please rethink and you may find the relatively simple error in what you just said, regarding all three points. (Three hints: 1) the original motor is not 100% efficient either. A bigger motor 2) weighs more and 3) costs more than two smaller.)


Please rethink yourself. Two smaller motors with the same total output of one larger motor will weigh more and cost more than a single motor. Two inverters instead of one, double the cabling, double the mounting hardware, double the axle shafts, and I'd suspect the motor weight itself would be higher for two motors than a single motor. I'd also suspect the efficiency of the two motor, two inverter system might be worse as well, though probably not significantly so.

In any case the context of the discussion is irrelevant regarding the weight, cost, and efficiency differences. If you want to say the extra weight, cost, and possible efficiency loss of an AWD system is worth it in a performance vehicle that is a separate issue.


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## Siwastaja (Aug 1, 2012)

Hi,

Motor efficiency is approximately constant regardless of motor size. It depends on motor manufacturer, model, type etc. more than size.

Motor weight is approx. linear with power (or torque, to be more exact), so two smaller motors with equal power to one bigger weigh _about_ the same. Again, this varies in practice.

In an AWD, extra drive shafts with CV joints naturally add a bit extra weight.

There indeed is some price offset from two smaller motors vs. one big, however, it may be negated because it is much more difficult to find very large motors. In fact, it can be seen that many diyers who want more power than a typical large motor can supply, have opted using two motors coupled together even for a 2WD mechanical diff configuration, simply because of the availability.

Sometimes distribution works miracles, sometimes a single centralized power source is better.

Multimotor system indeed has some increased complexity such as extra cabling and multiple controllers (those controllers can be smaller, however). This complexity however is exactly what enables the advanced features such as 4-wheel torque vectoring. It's up to the OP whether he wants to spend his money on a system like this, or is the "traditional" approach with just increased power enough.


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## Karter2 (Nov 17, 2011)

Siwastaja said:


> In an AWD, extra drive shafts with CV joints naturally add a bit extra weight..


 You are over simplifying a 2 motor 4wd system.
Its much more than a motor and drive shafts....
What about the transmission ( reduction box in the Tesla), differential, support sub-frame, wheel uprights, and any strengthening of the suspension components and mounting points, etc etc.. ????
Then of course you have to find sufficient space for all this !


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## Tomdb (Jan 28, 2013)

JRP3 said:


> Please rethink yourself. Two smaller motors with the same total output of one larger motor will weigh more and cost more than a single motor. Two inverters instead of one, double the cabling, double the mounting hardware, double the axle shafts, and I'd suspect the motor weight itself would be higher for two motors than a single motor. I'd also suspect the efficiency of the two motor, two inverter system might be worse as well, though probably not significantly so.
> 
> In any case the context of the discussion is irrelevant regarding the weight, cost, and efficiency differences. If you want to say the extra weight, cost, and possible efficiency loss of an AWD system is worth it in a performance vehicle that is a separate issue.



Your arguments can be viewed as invalid under certain cicrumstances. 

1. If the desired performance is above what is available on the market in one motor (around 100 kw+)

2. If you go with a thoroughly developed motor, depending where you source it it can be cheaper and lighter to go with two motor instead of one.

If you want something to replace a tesla roadster, i would suggest going for a two or more motor solution, preferably ac. There are a few compact and powerful permanent magnet motors out there. like the Emrax 100kw peak for 12kg, the motor is lighter than the inverters needed to drive it so go figure.


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## Karter2 (Nov 17, 2011)

Tomdb said:


> Your arguments can be viewed as invalid under certain cicrumstances.
> 
> 1. If the desired performance is above what is available on the market in one motor (around 100 kw+)
> 
> ...


 ?? All very odd statements considering a standard Tesla "S" motor is rated at 300+ kW, & 600Nm,... in showroom specification ?


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## Tomdb (Jan 28, 2013)

Karter2 said:


> ?? All very odd statements considering a standard Tesla "S" motor is rated at 300+ kW, & 600Nm,... in showroom specification ?


Tesla winds its own motors. When your working in volumes (as is tesla) its very quickly economically more viable to build one then two. then you can take the time and money to have the motor fit your exact specifications.

For a one-off or small series this is impossible to do for a reasonable cost so choosing available motor is better cost wise.


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## Karter2 (Nov 17, 2011)

Tomdb said:


> For a one-off or small series this is impossible to do for a reasonable cost so choosing available motor is better cost wise.


 OK, so for this exercise, we "chose" an available motor from a wrecked Tesla ! 

But as a Tesla owner, Kevin should be able to buy a new spare anyway ?

But also , i suspect is actually easier to produce a one off "special" wind than it is to make a full production run of special motors !


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