# smart roadster conversion



## ken will (Dec 19, 2009)

If you go to the upper right hand corner of this page and click on "Garage",
You might be able find several projects using a car similar in weight and/or aerodynamics to yours.


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## Yabert (Feb 7, 2010)

Hi

A short answer can be: Yes, for 25000$

The long answer is: You don't have enough place in a Smart to put all the energy need to travel 200 km. And don't forget, the aero on a Smart is relatively bad, so at highway speed you will need a good continous power (= high energy consomation).

Best advice: find a job close to your house or continous to pays gazole...


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## spiritonline (Sep 11, 2011)

Hi all, 

thanks for the quick reply's. @ yabert, I don't want to sound rude but I think your mistaking the "roadster" bit. My car is actual quite aerodynamic, and has different "space" then the regular smart's. Would this change things in terms of range?

here's a picture:


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## drgrieve (Apr 14, 2011)

The cd of the roadster (like all roadsters) is very poor @ 0.41 but with a small frontal area the final cda is ok @ 6.94 sq ft (0.645 m2)

See http://en.wikipedia.org/wiki/Automobile_drag_coefficient

For comparison 6.77 sq ft (0.629 m2) 1995 BMW M3 

So an old BMW M3 which can fit much more batteries would go further.

If you could charge at the end of your journey then 100km range might be possible not to mention half the price. At a big guess 20kwh would get you 100km at modest freeway speeds.

There are calculators that you can use to estimate it further. But your biggest issue is where do you fit the batteries - have you measured your estimated free space?


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## drgrieve (Apr 14, 2011)

There are two entries in evalbum to look at

http://evalbum.com/3911
http://evalbum.com/3513

Looks like 100 km is possible with a 15 kwh pack driving < 80 km/h with roof up.


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## Yabert (Feb 7, 2010)

spiritonline said:


> thanks for the quick reply's. @ yabert, I don't want to sound rude but I think your mistaking the "roadster" bit.


You are right! Smart Cabrio in mind.

Well, this one on your picture seem have a poor aero, but some picture of this roadster with roof and rear glass (picture) seem really sweet.

How many free place do you have in rear of the seats (before the motor) and under the front "hood"?
enough to put 20 or 25 Kwh of LifePO4 cells?


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## brainzel (Jun 15, 2009)

I don't know where you are located, spiritonline, but there are several conversions of smarts and at least two conversion kits from "Turn-E" and "Beatrix" out in germany.
I don't know if the rear drive unit is the same, but take a look.

I would recommend a HPGC AC50/Curtis Kit and Winston Battery or CALB LiFePo4 cells.
If you want to squeeze out as much space as posible to get many cells under the hood, you might be take the more expencive Headway or A123 cells.
It's a matter of money I guess  but 200km would be great (maybe unsolvable) challenge with current batteries.


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## spiritonline (Sep 11, 2011)

Wow, i didn't expect this much response but I'm glad its here  

@drgrieve: it's very cool to see it has been done before, altough the second roadster has twice the KW?
I will soon roughly measure the free space but it's kind of hard since the engine, gas tank etc will come out and I don't know how much space will be cleared by that.

@Yabert mine is the one without the rear glass although it does have a softtop  behind the seats is little space I would say about 15 cm deep, 50cm in width and about 100 in lenght. Unfortunately I can't really sacrifice the front "boot" since that's my only way of transporting at least something in this car  
Could you tell me how many big cells I would need for 25KW?

Once more, thanks for all the replies.


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## spiritonline (Sep 11, 2011)

@brainzel:
I'm located in the Netherlands so a trip to germany wouldn't be so bad. Il look into it! Thanks


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## Yabert (Feb 7, 2010)

spiritonline said:


> Could you tell me how many big cells I would need for 25KW?


Oups! Bad new! 75 liters isn't enough.

25 Kwh of cells represent around 162 liters of space and cost around 10000$

And space where is the gas tank??


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## spiritonline (Sep 11, 2011)

@all

I've just seen this (3.2V/7000Ah) battery on here: 
http://www.ev-power.eu/index.php?p=p_55&sName=lifeypo4-big-cells-(3.2v)

I know its insanely expensive but i took some quick measurements and it might just fit in the back. Now If i read it correctly to calculate Kw you multiply the volts with the Amp hours and divide it by 1000. That would mean 1 of these big cells would get me 22KW and that 2 of them might do the job for me?


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## spiritonline (Sep 11, 2011)

Its behind the engine, you can see it in the picture you posted.


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## major (Apr 4, 2008)

spiritonline said:


> That would mean 1 of these big cells would get me 22KW and that 2 of them might do the job for me?


Hi spirit,

That would be 22 kWh, not kW. And yeah, 2 of those cells would yield 44 kWh, which is more than adequate for range. But try to find a 100 kW motor rated at 6 volts 

Regards,

major


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## spiritonline (Sep 11, 2011)

I see... so could small additional batteries help crank up the voltage? 
(PS: how many volts are engines normally rated at?)


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## major (Apr 4, 2008)

spiritonline said:


> I see... so could small additional batteries help crank up the voltage?
> (PS: how many volts are engines normally rated at?)


Hi spirit,

Please refer to electric electromechanical conversion devices as motors, not engines  And no, you can't mix cells of different capacity in a battery pack. All the cells in the series string must be equal Ah rated. The typical motor voltage for EVs will require battery packs in the range from 100 to 300 V depending the desired performance and component choices.

Regards,

major


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## spiritonline (Sep 11, 2011)

thats a shame  This looks promising: http://www.a123systems.com/products-systems-energy-core-pack.htm but it says it's not availible for consumers 

(I will keep the motor vs engine story in mind)


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## spiritonline (Sep 11, 2011)

Could someone please tell me how many of the A123 20AH would be needed for my goals?
(and possibly also explain how many volts / ah I need total?)


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## major (Apr 4, 2008)

spiritonline said:


> Could someone please tell me how many of the A123 20AH would be needed for my goals?
> (and possibly also explain how many volts / ah I need total?)


Have you read this? 

http://www.diyelectriccar.com/forums/showthread.php?t=669&redir_from=668 

And contained in that, this? 

http://www.diyelectriccar.com/forums/showthread.php?t=11709


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## spiritonline (Sep 11, 2011)

Yes but won't that mean that building a battery pack with those battery's is impossible? 
Because if I calculate it I would require 800 of them to get the 200KM range but that would result 2640 volts? As I understand it the wrap9 motor supports up to 170volts.

(my apologies if I say stupid things now)


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## dtbaker (Jan 5, 2008)

spiritonline said:


> Would this change things in terms of range?
> 
> here's a picture:


that is a very cute car!

I think you could have a super fun conversion using Warp9, SolitonJr/Synkromotive controller, and 144v CALB system... only issue is that with space available I dunno if you'd have room for the 200ah cells you'd need to get close to 200km. It would be VERY tight and fill all available space I'd guess.

You'd have a little more range with 144v x 180ah = 25.9kWhr than 120v x 200ah = 24 kWhr, but it might be an easier fit one way or the other that would determine your limitations. With an untested body style, you can only 'guess' at what kind of consumption you are going to see... faster highway speeds eat a LOT more energy to overcome wind resistance that goes up drastically with speed.

DC motor/controller/charger 'electrics' and misc materials are going to run you around $6k-$8k, and the batteries depending on how big you can actually squeeze in there (100ah, 160ah, or 200ah), are going to run you between $5k-$11k

If you go AC, you may extend range 10%-15%, but pay a LOT more for the motor/controller, a good $1000 or $2000 more than comparable power in DC.

all assuming you can get CanEV.com or someone else to build you a tranny adaptor.


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## major (Apr 4, 2008)

spiritonline said:


> Yes but won't that mean that building a battery pack with those battery's is impossible?
> Because if I calculate it I would require 800 of them to get the 200KM range but that would result 2640 volts? As I understand it the wrap9 motor supports up to 170volts.
> 
> (my apologies if I say stupid things now)


Look into series/parallel wiring of cells for the battery pack


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## Yabert (Feb 7, 2010)

spiritonline said:


> Because if I calculate it I would require 800 of them to get the 200KM range but that would result 2640 volts?


You will need to put build a pack of 200Ah and 256v (10 x 20 Ah) x (80 x 3.2v) = 51.2 Kwh.
Half that will be good.

As motor, if you consider DC, you can probably try a Kostov 9 motor.
Light weight, good power 60-75 Kw (high RPM) and not an extreme torque who can destroy a common transmission.


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## algea07 (Oct 1, 2010)

http://evalbum.com/3911 it says that he gets 100wh/km so he wouldn't even need a big battery pack 20kwh should do it, say 25-30kw to be safe. 

i think that the thundersky or calb 200amp batteries are the same size as the 160 amp, so you could get for example 45 200 amp batteries which will have 28.8kwh (plenty).
pros: cheap and have enough power to get you 100-150hp
cons: heavy, and they're big and can't be installed on sideways or upside down

or you could use headway say around 700 cells. at around 25kwh.
pros: they are a smaller cell and you can get creative with where you put them, under the sets where the fuel tank used to be, they'll fit where the bigger thundersky or calb batteries wont. they have lots of power more then you could ever dream of in smart roadster. (provided you have a motor and controller that allow you to use it)
cons: they are a little bit more expensive 10-20% more expensive. and you'll have 700ish batteries to wire together, it wouldn't be hard just time consuming.

for a motor, i'd suggest either a 9" kostov or netgain. both these are common choices. some basic stats:
kostov: $1500-$2000 55kw peak 45kg
netgain: $3000-$3500 75kw peak 50kg
(both these motors can be abused to get more then the rated power, i've heard the netain can get 140kw)

the links on the right on the home page are a good place to have a look at components and cost.


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## marc02228 (Jan 15, 2011)

Be careful with that Warp 9 Motor, it will probably kill the transmission...
The Smart Roadster might be my next project, too.
The standard ICE has a max torque of 95 to 110Nm

For the batteries, my favorite right now are the 8Ah (P) Headways and the A123 20Ah. But the Headways will be much easier to assemble.


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## Korben_Dallas (Feb 27, 2009)

Hi all,

the smart roadster is indeed a very nice car to convert. Other than the coupe where you have plenty of space underneath the seats the roadster has space only behind the seats or above the engine where the gas tank used to be. See picture on the right:

http://www.ipp.tu-clausthal.de/forschung/projekte/elektromobilitaet/

In the coupe we use 30kW 3phase motors from italy and curtis 1238 controllers. Since the rear axle of the Smart 42 and the roadster are identical all brackets will fit. In normal city driving we get a range of 140km @25°C out of a 15.8 kWh pack of CALB cells, on the highway it's about 100 to 120km depending on the way you drive.

In my opinion the only way to get more kWh into the roadster is to go with smaller cells to make use of every last corner. We did a Smart with Panasonic CG 18650 cells, the same ones used in the Tesla. Aside the fact that you need to be very careful at assembling the cells (we had it done by a company [BMZ] in germany) they also get very hot. So while you can get more power into a small space you have to think about cooling.

In the coupe the stability of the car is much improved because the cells are located beneath the seats. In the roadster you would move a lot of weight to the back of the car and up. I don't know how that will alter the driving characteristics. Maybe it doesn't matter because the car has a low center of gravity to begin with.

Ciao, Christian]
TURN-E.de


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## brainzel (Jun 15, 2009)

25kWh out of Panasonics CG 18650 cells would be a challenge.
About 3.100 cells have to be permanently connected and cooled (Christian said it already).
180,00 Wh/kg instead of 114,29 Wh/kg (Sinopoly SP200Ah) sounds good, but 728,40 €/kWh (Panasonic) to 259,24 € (Sinopoly) is three times expensive.

Monitoring every cell would be simply impossible, to change a damaged cell (if you ever found it) would be like a rebuild.


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## Korben_Dallas (Feb 27, 2009)

With the 18650 cells you don't manage or monitor every cell. In fact they are secured by a small nickel wire and a PTC at cell level. You hook up the cells to modules, the modules are connected in series, the modules get monitored like the big CALB or TS cells. In our case we built modules out of 70 cells parallel, which gives you a 154Ah module. With the curtis 1238 we are restricted to 110V (according to Jack they are safe to 120V and blow their final whistle at 135V) so we use 30 or 32 modules. These cells have a nominal voltage of 3,6V! Our pack has 17kWh and fills up the space of 1000 x 495 x 170mm. That's the space the gas tank used to occupy. If you can find room behind the seats you might pack another 8-10kWh.

For the next Smart we will built a pack with Samsung 18650 cells. They warm up to a cosy 30°C at 5C discharge. With 84cells in parallel that's a 184Ah module. We will reach 2,5C very seldomly so I don't fear the heat too much.

Still for someone who wants to build the battery pack himself going that route is not worth the trouble. You need a company who can spot weld the modules professionally. If you can find someone who does the job thoroughly you'll notice the the price for the cells is more in the 340 €/kwh range :–)

I'll put some pics of a disassembled roadster on a server if that helps. 
If you want to go with an AC drive, up to 30kW (liquid cooled if you like) we can get you very far in the conversion.

regards, Christian]

PS: check out our profile on http://www.evalbum.com/3612. There you'll some pics of the rear axle and the motor-transmission assembly.


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## gor (Nov 25, 2009)

algea07 said:


> http://evalbum.com/3911 it says that he gets 100wh/km so he wouldn't even need a big battery pack 20kwh should do it, say 25-30kw to be safe.
> 
> i think that the thundersky or calb 200amp batteries are the same size as the 160 amp, so you could get for example 45 200 amp batteries which will have 28.8kwh (plenty).
> pros: cheap and have enough power to get you 100-150hp
> ...


 edit:
http://www.evsource.com/tls_warp11HV.php
http://kostov-motors.com/files/compare.pdf

warp9 - 143lbs, 65kg
warp11 - 233lbs, 106kg
warp11hv - 223lbs, 101kg
warp13 - 367lbs, 136kg

k9.220v - 106lbs; 48kg
k11.250v -81kg


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## drgrieve (Apr 14, 2011)

gor said:


> http://www.evsource.com/tls_warp11HV.php
> http://kostov-motors.com/files/compare.pdf
> 
> 
> ...


WarP 11 233, 106
HV 11 223, 101

Warp 11hv is lighter than the warp 11. according to the site you linked to.

The warp 13 is the one that is 136 kgs


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## gor (Nov 25, 2009)

drgrieve said:


> WarP 11 233, 106
> HV 11 223, 101
> 
> Warp 11hv is lighter than the warp 11. according to the site you linked to.
> ...


right, it should be: 

http://www.evsource.com/tls_warp11HV.php
http://kostov-motors.com/files/compare.pdf

warp9 - 143lbs, 65kg
warp11 - 233lbs, 106kg
warp11hv - 223lbs, 101kg

k9.220v - 106lbs; 48kg
k11.250v -81kg

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corrected, thanks


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## gplate (Sep 28, 2011)

Many people forget the concept of a slimline battery pack under the floor pan.
1. Can be set up for quick removal and if funds allow a quick turnaround charge by a pack swap.
2. Stream lines the vehicle underside full length carbon/fiberglass.
3. Lower center of mass and better weight distribution.
4. Better air circulation around battery pack as front to rear/side ducting is improved.
5. Attachment and grid design pack break up into 60volt cellular units with individual contractors adds low voltage electrical safety and tortional rigidity from unit separation channels ( better handling & protects wiring loom).
6.Internal vehicle space saving would set up for a larger onboard charger, dc-dc inverter, controller and BMS management module


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## eUKenGB (Feb 21, 2019)

Could anyone here who has done a Smart conversion and used the original gearbox describe how they use it?

I'm particularly interested in the Roadster with its auto shift system. If keeping all the original gears, is the clutch actuator operation modified at all? Normally the clutch is disengaged at low speed and when stationary, but that is not required, or even desirable with electric drive. However keeping the clutch makes sense in order to shift while driving.

How have others dealt with this?


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