1500w 60kmh Optimistic?

EXPERIMENTAL EV · Jan 8, 2017

Hello there. I am currently waiting for a 1500w inrunner scooter motor and controller. I will be putting this in a miniature dirt bike frame, which used to have a 49cc pos in it producing 1.8kw. With my current gear ratio I have a No load top speed of 60 kmh, Is this gearing too tall? Should I increase the gear ratio.
Link:
Motor and Controller:
https://www.aliexpress.com/item/1500W-48V-Brushless-Electric-DC-Motor-1500W-Electric-Scooter-BLDC-Motor-BOMA-Brushless-Motor-Scooter-Parts/32620049151.html?spm=2114.13010608.0.0.jF21lX
https://www.aliexpress.com/item/1500W-1600W-Electric-Scooter-Controller-48V-Brushless-DC-BLDC-Motor-Controller-Scooter-Spare-Parts/32628585138.html?spm=2114.13010608.0.0.jF21lX

Thanks in advance :lol:

dustNbone · Jan 8, 2017

It's going to depend on the no load speed of the respective motors. If the electric motor turns at exactly the same no load speed as the 50cc gasser, then you might be a touch over geared assuming the 1.8Kw is an honest figure, and you're only actually making 1.5kw from the inrunner. The actual electric output will be more dependent on the controller than the motor itself though, and it's no load RPM will be a product of kV (RPM per volt) multiplied by battery voltage.

At very least we'd need to know specifically which 50cc engine is being replaced with which electric motor.

EDIT: It looks like that motor is supposed to turn 5300 RPM at 48V? 5300RPM is pretty slow for a 50cc engine, so even with equal power output I'd think your top speed would be lower than with the gas engine. You might be able to increase the voltage a bit to get more RPM, but that would mean a different battery, and possibly a different controller.

Hopefully someone on here who has done a similar conversion has some more specific advice to give.

Boulter EV · Jan 9, 2017

My estimate would be that it'd go 60kmh but you'd be limited by gradient and the performance would feel poor.

The easiest way to work this out is to calculate total tractive effort and total resistance. In your total resistance calculation you should include a gradient, which should be determined based on where you intend to drive this thing.

Do you live in a hilly area or is it quite flat?

Something else to consider is the terrain. If you want to take this thing off road, mud and ruts will demand more torque.

If you could work out the wheel torque and power, answer the two questions above, and tell me the gross mass of the bike, which will need to include the rider mass, I should be able to give you an idea of performance.

If you're not sure how to work out wheel torque and power, if you give me the motor torque and power, the total gear ratio from motor to wheel, the drive wheel diameter, I'll make some assumptions on efficiency and work it out for you.

EXPERIMENTAL EV · Jan 10, 2017

dustNbone said:
It's going to depend on the no load speed of the respective motors. If the electric motor turns at exactly the same no load speed as the 50cc gasser, then you might be a touch over geared assuming the 1.8Kw is an honest figure, and you're only actually making 1.5kw from the inrunner. The actual electric output will be more dependent on the controller than the motor itself though, and it's no load RPM will be a product of kV (RPM per volt) multiplied by battery voltage.

At very least we'd need to know specifically which 50cc engine is being replaced with which electric motor.

EDIT: It looks like that motor is supposed to turn 5300 RPM at 48V? 5300RPM is pretty slow for a 50cc engine, so even with equal power output I'd think your top speed would be lower than with the gas engine. You might be able to increase the voltage a bit to get more RPM, but that would mean a different battery, and possibly a different controller.

Hopefully someone on here who has done a similar conversion has some more specific advice to give.

Hi there. It originally had a 49cc cag producing "1.8kw" but it also had a 3:1 reduction gearbox before the final drive, I will attach some pictures of the bike im converting

Btw, Fat chunky wooden box is the Battery box and seat

Thanks

EXPERIMENTAL EV · Jan 12, 2017

No one else?

1500w 60kmh Optimistic?

EXPERIMENTAL EV

10 mW

dustNbone

10 kW

Boulter EV

10 mW

EXPERIMENTAL EV

10 mW

Attachments

EXPERIMENTAL EV

10 mW

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