# Performance Calculation's/Estimation



## Jordysport (Mar 22, 2009)

Heya all, I have a Single seater race car and i have calculated the all up weight is 250kg and was wondering if you all could just give a guestimate on the numbers

Kostov 144v DC Series motor
Zilla 1kw Motor
Thundersky 90ah cells

thats the main things you need to know really, and its geared for a top speed of 110mph 

Many thanks


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## madderscience (Jun 28, 2008)

I am assuming 250kg is for just the car chassis.

144V (or about 45) thunder sky 90AH will weigh about 2.5kg/cell * 45 or roughly 110kg.
You don't say what size the kostov is but a 8" advanced DC weighs about 60kg. The controller and wiring will probably contribute another 10 or 20Kg, so just in the EV parts you have 200kg.

as for horsepower, you can compute peak horsepower by taking the maximum wattage you can get to the motor and dividing by 746 to get horsepower.

A Z1K will put up to 1000 amps through the motor. You won't get any 144V out of those batteries at 1000A due to voltage sag though. 100V is probably the highest you could expect with fully charged, warmed up lithium batteries. So 100,000 watts divided by 746 is about 135 electrical horsepower. The motor efficiency will vary from 0 (at stall) to around 80% at its peak operating efficiency. So the electrical to mechanical conversion will drop your shaft horsepower to about 100hp peak or so.

The car's performance will be biased more towards low end torque than the gas engine that was there before. you will probably need to play around with gearing to keep it controllable and get the right mix of torque and top end.

100 horsepower in a 5 to 6 hundred KG vehicle (counting driver weight) seems pretty good to me.

Keep in mind that as of last time I checked, the thunder skys are a 4C continuous rating battery. that means you cannot pull more than 4X their AH capacity on a continuous basis without overheating and damaging them. The latest TS batteries also claim a 10C impulse (not more than a couple of seconds). So with what your are proposing you are pushing the limits of these batteries.

Good luck.


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## Jordysport (Mar 22, 2009)

madderscience said:


> I am assuming 250kg is for just the car chassis.
> 
> 144V (or about 45) thunder sky 90AH will weigh about 2.5kg/cell * 45 or roughly 110kg.
> You don't say what size the kostov is but a 8" advanced DC weighs about 60kg. The controller and wiring will probably contribute another 10 or 20Kg, so just in the EV parts you have 200kg.
> ...


250kg Fully laden with driver and complete ev conversion, this is proper british engineering, colin chapman's principals. the chassis weighs about 40-50kg, maybe a bit more towards 80kg. 

iirc the voltage sag of those cells are approximatly 24v bringing it to 120v edit: may be different for 1000A also the kostov weights about 38kg. ok so approx 100 Hp for 250kg is pretty good seeing as the motorbike engine in it atm is less than that. also TS are 3C and 20C impulse, now the Hillclimb will last for 30 second runs, which probably contain 4x 5 second full throttle sections. so 3C is 270A , 20C is 1800A.

But this all seems a grey area for how long this can be sustained. that is the question whether to go to 180Ah or a higher C rating cells (headway)

all advice is appriciated


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## Duncan (Dec 8, 2008)

Hi Jordy

I am building a road car with a target weight of 650Kg and a similar spec

I think you should be looking at available torque and comparing it with the weight on the driven wheels
You may find that you are tyre limited up to a relatively high speed

In my case with more weight but less tyre grip I decided that I did not need a gearbox

I am interested in the amount of current that you can safely take from your batteries, please let us know what happens!!!

One solution may be to run with a relatively low Ah battery pack (for its weight) and fit some ultra-caps across the pack.


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## Jordysport (Mar 22, 2009)

Duncan said:


> Hi Jordy
> 
> I am building a road car with a target weight of 650Kg and a similar spec
> 
> ...


well taking into account that the tyres on the rear are 200mm wide each and Slick tyres. i am thinking maybe a 144v 120ah Headway pack which would give a constant draw of 1200A and a peak of somin like 3600A. just to prevent confusion this is the vehicle:

http://www.fastroadandtrack.co.uk/frat/usergraphics/2791358e905388278014c54def60ba08.jpg


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## Jordysport (Mar 22, 2009)

Ok small update, getting the chassis soon, gonna go for 144v Kostov 9"motor (bit more ummph than a warp9) and Headway cells, but not sure how many Ah i need as there is no Cd or frontal area for the car aswell as RR of those big slicks, hill climbs are about 40 secs long so only needs to run for 5 mins or so and the hill is 1km long so roughly 5-10km range??

and as for the controller... do i really need 1000A Zilla??? looking for performance figures of: (no gearbox- just motorcycle gears)

Total weight 250-300kg
0-60 - 3.6 seconds
120mph top speed.


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## DavidDymaxion (Dec 1, 2008)

I'm a Kostov owner, so you know my bias, but I thought the Warp motors were tougher -- but I'd love to hear the Kostov is tougher. Do you mean the Kostov can take more Volts? More Amps? More rpm? Is heavier? Higher temp wiring? Just curious.

Why not go as high in Voltage as the motor can handle?

Remember your batteries will sag and there are inefficiencies in your system. 144 V * 1000 A / 2 --> 72 kW battery --> ~72 rwhp. That's not a gob of power, maybe you should be thinking higher voltage and/or higher current.


Jordysport said:


> Ok small update, getting the chassis soon, gonna go for 144v Kostov 9"motor (bit more ummph than a warp9) and Headway cells, but not sure how many Ah i need as there is no Cd or frontal area for the car aswell as RR of those big slicks, hill climbs are about 40 secs long so only needs to run for 5 mins or so and the hill is 1km long so roughly 5-10km range??
> 
> and as for the controller... do i really need 1000A Zilla??? looking for performance figures of: (no gearbox- just motorcycle gears)
> 
> ...


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## Jordysport (Mar 22, 2009)

DavidDymaxion said:


> I'm a Kostov owner, so you know my bias, but I thought the Warp motors were tougher -- but I'd love to hear the Kostov is tougher. Do you mean the Kostov can take more Volts? More Amps? More rpm? Is heavier? Higher temp wiring? Just curious.
> 
> Why not go as high in Voltage as the motor can handle?
> 
> Remember your batteries will sag and there are inefficiencies in your system. 144 V * 1000 A / 2 --> 72 kW battery --> ~72 rwhp. That's not a gob of power, maybe you should be thinking higher voltage and/or higher current.


Well, the kostov is only 41 kg and the updated one takes 168v but frankly i don't know if i have the space for those extra cells, and i am UK based and their factory is in eastern europe so much easier to get hold off and much much cheaper! Could do with an excel doc that you can calculate range etc, as i've lost mine, but got the performance excel spreadsheet so just need to fiddle about with that really. if i have room i will get the Kostov 250v 9" or 11" and crank it upto 250v might be able to squeeze the cells in the side pods. but its not all about power, in a 250-300kg car (total weight after conversion) it doesn't need a huge amount of ummphh.


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