# Motor strong enough??



## major (Apr 4, 2008)

Hi gi,

While 10kW sounds adequate. ... I don't know. Especially that Golden motor. No experience with it, but have noticed a number of negative reports and no positive. Take a look at this thread and notice his motor temperature issues. http://www.diyelectriccar.com/forums/showthread.php/road-legal-streetquad-conversion-80380p20.html

Good luck, 

major


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## Duncan (Dec 8, 2008)

Hi gi

250Kg with driver??
A recumbent trike (pedal powered) can come close to 150kg using pushbike parts,
If you are using motorbike parts and are very careful to make it as light as possible you may get down to 350kg with driver but I would start by planning for at least 400Kg

Don't pay to much attention to the weights that people claim unless they have weighed their cars themselves
Kit car manufacturers always seem to massively low ball the weight of their vehicles


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## giantpt (Jul 14, 2016)

Duncan said:


> Hi gi
> 
> 250Kg with driver??
> A recumbent trike (pedal powered) can come close to 150kg using pushbike parts,
> ...


I appreciate your observation and You might be right, but besides correcting peopple do you have any information related with this topic to add?
Consider than 350kg with driver.
By the way, lets add 40kg for the battery (72v, 150A), 17kg for the motor, 2kg for all the BMS's.
If you find this info usefull, I can tell that all the chassis will be made from carbon/pvc sandwish and some parts from fiber glass.
Unfortunatly I don't hace a scatch for it because I am still looking for all the technology and its exact dimension to start designing the car.

So, now it really urgent for me to know which kind of performance (speed and climbing habilities) can I get from a 10kw broshless motor on a 350kg car with thin motorcycle tyres and a low chassis profile a bit aerodynamic.

Thanks


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## Duncan (Dec 8, 2008)

Hi gi
My car is a scratchbuilt two seater and it weighs 750kg

You need to specify parts that can stand all of the loads that you are going to apply - you should NOT go onto the public roads with a vehicle that will collapse if it clips a curb

There is a kind of spiral here - making it lighter means that it can be made even lighter 
Or vice versa!

You talk about carbon fiber - are you going to use a wet layup? or pre-pregs?
You should understand that if using a wet layup carbon fiber is more difficult to use and you will end up with a higher resin percentage and a part that has a lower strength to weight ratio than S glass
90% of "carbon fiber parts" are heavier and weaker than they would have been if made as glass fiber

To your question
If you are making a low speed city vehicle then 10Kw would be more than enough for a 350kg vehicle
Such a machine would be able to easily keep up with traffic and reach 40mph

If you want sporty performance and 60mph - then you would need a heavier machine (to resist the loads) and more than 10Kw


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## giantpt (Jul 14, 2016)

Hi Duncan, I do have years of experience with carbon by resin infusion and prepreg out of autoclave. Making a stif and light car is not an issue for me, my biggest doubt is the motor stuff which is not my speciality.
40mph is not bad at all, well, if I could have a bit more preformance would more fun, of course.


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## electro wrks (Mar 5, 2012)

Here's a 15kW continuous motor: http://www.electricmotorsport.com/e...ss-57hp-liquid-cooled-pmac-motor-24-120v.html

$1500US$ is a little steep for me. But it is only 35lbs.,16kilos and very compact.


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## zsnemeth (Jan 4, 2012)

giantpt said:


> Hi guys,
> 
> I am planning to build a single seat light car to drive on city. It will be something like the Wessl Quad, which is based on a motorcycle but, building a car around that idea, like I said, a single seater, a bit lower and wider, with the same type of wheels and tyres, a bit long suspension but not so long as theirs.
> I suppose the weight will be somewhere around 250kg with driver.
> ...


Hi G,

Have a look around on evalbum.com, there are three small cars with this motor.
Here is one of them: http://evalbum.com/4602 , try to ask Him, how things goinq.

Good luck!


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## Yabert (Feb 7, 2010)

giantpt said:


> My big questions is:
> Would a 10kw BLDC motor enough to make it move at a max speed of 50km/h and able to climb hills?


10 Kw is all I need to drive my 950 Kg (with driver) Smart at 80-90 km/h. So in your case that seem promising but there is two tricks.

1- You will need way more power to climb long hills. Do you have lot of important hills where you are?
2- (the most important) Obtain this 10Kw from the motor can be impossible in some case with a single speed ratio. At lower speed the power is reduce. Find the perfect ratio between top speed and hill climbing ability can be tricky.


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## giantpt (Jul 14, 2016)

Hi Yabert,

My area is not flat but quite, in the centre of the city we have a 7% climbing avenue which is about a quarter a mile long, than a bridge with a climb as well but apart of it the area is prety much flat, just with slight ups and downs, for you to imagine, they're not hard for a bike.
Regarding the gear ratio, well, it will have to be trial and error, I'll have to mill different gears on my cnc and check which will better serve the needs or, in a worst case scenario think about using something like a scooter gear box which is progressive. I'll have to think about it.

Well, knowing that a 10kw motor is a good bet are excellent news.

Thank you


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## giantpt (Jul 14, 2016)

To control the motor I am thinking about a RoboteQ controller which can handle 72v and can output a max of 150Amps. I like these controllers, I am well familiarized with them as I use them since 2010 to control my camera systems. Its impressive the amount of settings we can handle on it and it can be programmed with custom scriptings.
To manage all the car I think I'll use a 32bit arduino due on hich I'll connect all the sensors, pedals, motor controller and so on.
My ideia is also to build an F1 style steering wheel where I'll have a nice LCD and all the switches and pots needed to control the car and its features and with a quick release to take it away.
I will count with the precisious help of a friend of mine that is a programmer engineer for the firmware side of the project. i have discussed with him already and one of the features we want to implement is a personal RFid key to the car to be set according with the person that will drive it, like torque available, max speed allowed, accelerations, etc.
To power the car I think I'll use the NCR18650 cells from Panasonic and build a Tesla style battery pack of 72v and 150 amps, hopping to get more than a hour of driving time and more than 100kms of range.

I think it will be fun to run this project, I can wait to start with it
As I told before, I am first checking all the hardware I'll use to start the CAD design around it.
Lets see what comes out.

Cheers


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## Yabert (Feb 7, 2010)

giantpt said:


> To control the motor I am thinking about a RoboteQ controller which can handle 72v and can output a max of 150Amps.


Maybe take time before buying this controller. It's only 10 Kw peak and supposed to be 7Kw continuous.
The reality is you can find DC brush motor controller with 30 Kw peak for the same price and complete kit for 1K$
http://www.evdrives.com/category_s/1860.htm

With some of those kit, your small car will fly!
And you can do a two seaters without problem.


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## giantpt (Jul 14, 2016)

Well, I was expecting the brushless motors to be more efficient than the brushed ones.
Whats the real difference between both in terms of performance?
At least I know that a brush motor has some brsuh maintenance.


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## Sterling2015 (Jun 24, 2015)

Thinking that your motor requirement looks good for :
http://www.rhoadescar.com/

Hybrid, human/electric power.

Axle already has gear for electric conversion.


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