Electric scooter (brushless or brushed motor)

[tcmtech]

I have a electric scooter I set up for my niece and it has a 300 watt brush type DC motor. No problems with its motor durability either.

With her and her 30 or so kgs it moves around quite well but with my 120+ its way too under powered.

 

[audioguru]

Your scooter is TINY. I saw one on my street driven by a little kid. There are many of them without a motor.

My son bought and sold "pocket bikes" that were tiny electric motorcycles that you sat on. They were fun.

 

[Mr RB]

I have a electric scooter I set up for my niece and it has a 300 watt brush type DC motor. No problems with its motor durability either.
...

Kids type scooters are always underpowered and with small weak abtteries and very "enthusiastic" on the spec. The actual size of motor used in most cheap scooters is about 100W and will draw about 8A from the 12v battery IF the battery can handle that which a lot of those little 12v SLAs can't anyway.

A real 300W motor (ie drawing about 12A at 24v) would be powerful enough for a well geared scooter and 400W getting to about the ideal size.

So what you are saying? That i should rather buy brushless than brushed motor? ...
So... which one to buy now?
...

I'm not Audioguru but i think he was talking about tiny lightweight model aeroplane brushed motors failing, which is normal as they push them way past their safe specs.

My personal opinion is that you should get a DC brushed motor designed for electric vehicle use. It will make good low RPM torque, handle heat well at low RPMs and have large sturdy bearings and work well with a simple PWM controller. It will be simpler, more rugged and cheaper.

Like this kind of thing;
**broken link removed**
or one a bit larger.

Anyway, it's your decision. Just be prepared that you might need to change the gearing.

 

[tcmtech]

I rebuilt my nieces scooter to use 6 sets of 1.8 Ah 14.4 volt NiCad drill battery packs instead of the two 12 volt 5 Ah LA batteries and it amp tested at about 30 amps with a 28 volt input.

For her out around the farm on grass and gravel it worked great but for us big guys we have too much mass and pushed the little tires too far into the ground which sucks up too much power.

Personally for a adult I would design it around a 1000 watt motor and a much larger battery system as well. That and larger wider tires too!

 

[rascupanamuha]

I have been searching on ebay and so for DC brushed motors, but with shipping to croatia they (500W) costs more than 110$.
But after i have found this video: https://www.youtube.com/watch?feature=player_embedded&v=NQO_faWhybo , i came to decision that i will buy the same motor. I am thinking of this one: https://www.hobbyking.com/hobbyking...SK3_6374_192kv_Brushless_Outrunner_Motor.html

On 24V lipo battery (6S), it should be very powerfull (around 1.5kW maybe), and it is cca 120$ with ESC controller, so i think it is much better option and not at all more expensive

 

[jpanhalt]

Maybe you can find one in a used treadmill/exercise machine?

The old, direct-drive automotive starters are powerful and have been used in electric vehicles, but they are generally not rated for continuous duty. You might find something smaller (e.g., an old motorcycle starter), that can take the duty cycle you need.

DC motors from treadmills are probably rated for more duty. Although most today are probably rated for 90V or more, I bought one on a surplus site several years ago that was 12V. It was such a nice motor, that I bought lot lot more of them. Look around, you might find something a lot cheaper than the shipping cost.

John

 

[Mr RB]

... i came to decision that i will buy the same motor. I am thinking of this one: https://www.hobbyking.com/hobbyking...SK3_6374_192kv_Brushless_Outrunner_Motor.html

On 24V lipo battery (6S), it should be very powerfull (around 1.5kW maybe), and it is cca 120$ with ESC controller, so i think it is much better option and not at all more expensive

Cool. Part of the work with design is just being able to finalise what parts to use. Now the choice of gearing etc gets easier.

I hope you post back as you complete the project. It's not the motor choice I would have made but it will still be interesting seeing the performance and gearing etc and time before motor/driver failure.

 

[rascupanamuha]

Cool. Part of the work with design is just being able to finalise what parts to use. Now the choice of gearing etc gets easier.

I hope you post back as you complete the project. It's not the motor choice I would have made but it will still be interesting seeing the performance and gearing etc and time before motor/driver failure.

I will definitely post back here once i finish this. I will also post how is it going
But i will start with all this not before 28.1., because i have exams to pass

 

[rascupanamuha]

I have some more question:
If you have 2 motors with 2.7kW.
One has 4600RPM, the other one has 5900RPM
First one has max current of 80A, the other one 70A
Second one is a bit shorter (no diference in diameter)

Would you buy first or the second one and put 3.6 (on fist one) or 4.5 (second one) gear ratio, to go with the same speed (max=10m/s)
I think it is better to buy second one, with the same power, it would have more torque, or for the same torque it would use less A (so longer battery life)
Am i right?

First one: https://www.hobbyking.com/hobbyking...SK3_6374_192kv_Brushless_Outrunner_Motor.html
Second one: https://www.hobbyking.com/hobbyking...SK3_6364_245kv_Brushless_Outrunner_Motor.html

 

[Mr RB]

I'd buy the one with the largest frame, largest shaft, largest bearings, etc.

Re the power used, a well-geared motor with PWM efficiency will use about the same power it will depend mosty on load (where and how you ride) and not on the exact specs of the motor itself.

 

[rascupanamuha]

Here are some pictures of what i have done so far

Now i need to buy mechanical disk brakes and put them on, and install front wheel and steering wheel assembly (thats what i will do today)
I am thinking weather to use bicycle gear for transmission or transmission that is used in cars (i think it is called "pulley")
Motor and electric speed controler and other electronics will come in the last stage of building it but it may come soon

 

[arunb]

regarding exercise, you could design your system on the lines of a bicycle, say a motor that can be engaged whenever required, when the battery gets discharged the rider would have to diengage the motor and use the pedal (as in a bicycle), this could also charge the battery.

 

[rascupanamuha]

Sorry for so late reply i could have done it in much easier way (just put motor on scooter for kids), but i wanted to do all myself. Here is how it is going. Scooter is 95% done, only motor and ESC are missing, and other elentronics. It should all come soon




What do you say about it?

 

[ericgibbs]

Here are some pictures of what i have done so far

Hi,
You have made a really nice job of the metal work.
E.

 

[rascupanamuha]

Thank you
I hope electric part would be also nice. We will see when it motor and ESC come

 

[rascupanamuha]

Here is a video of it
https://www.youtube.com/watch?v=e4aytrNBYJg

 

[kubeek]

Seems you are braking using your foot, that could use some improvement

 

[tcmtech]

High ground clearance! Planning to do some off road riding with that thing?

 

[rascupanamuha]

I dont know yet
But it will be smaller by 4cm because in that space i am standing on i will put all electronics and batteries

There will be front and rear mechanical disk breaks with 160mm rotors, but for now, yea i am breaking with my foot

It is not finished yet but it would be very soon, and then i could make 20km without any problem and with speed of 27km/h

 

[arunb]

Does one need a road worthiness certificate for this bike ?? Is it legal to operate such vehicle without a road worthiness certificate ??

What about insurance claims say you accidentally ram a senior citizen walking on the road (I am assuming both pedestrians and bikes are allowed in the same road) ??