Motor necessary to power a small cart

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Discussion Overview

The discussion revolves around whether a motor with a torque rating of 6.5 kg/cm is sufficient to power a small go-cart carrying a total weight of approximately 45 kg at a speed of 6 km/h. The context is a personal project rather than an academic assignment.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the adequacy of a 6.5 kg/cm torque motor for the specified weight and speed, suggesting that the torque available at a 1:1 ratio would be insufficient.
  • Another participant calculates the power output of the motor, concluding it to be around 13W, and compares this to typical power ratings for kids' and adult carts, indicating that the motor is too small.
  • A suggestion is made to consider a 500-1000W scooter motor, along with the necessary battery and controller specifications.
  • One participant corrects the power output calculation, stating it is actually 9.4W based on a different RPM rating, and compares it to a replacement motor rated at 170W, which is noted to be more powerful and cheaper.

Areas of Agreement / Disagreement

Participants generally agree that the 6.5 kg/cm motor is likely insufficient for the intended application, but there is disagreement regarding the exact power output and the implications of that for the project.

Contextual Notes

There are unresolved assumptions regarding the efficiency of the motor, the impact of rolling resistance, and the specific requirements for the go-cart's performance.

dracalb
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Is a 6.5kg/cm torque motor enough to move (let.s say at 6km/h) a small go cart and a kid (total w. about 45kg)?

this is the motor: http://www.amazon.com/dp/B00T48KC1Q/?tag=pfamazon01-20

PS: this is not for a homework but for a for-fun project.
 
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Right offhand I'd say no. It looks like the RPM is 200, and I'm assuming the torque is 6.5 kg-cm(?). So available torque at 1:1 ratio on a 25 cm diameter tire would be about half that, or 3.25 kg-cm. To get to 6 km/hr with the same tire you would need about 3:1 speed increase, which would reduce the torque to about 1.1 kg-cm. With all the other considerations (rolling resistance, elevation increases in common roads, even flat ones) I don't see it working.

Anyone else?
 
Power = Torque * angular velocity
Power in Watts
Torque in Nm
angular velocity in rads/s

200rpm = 200*2*pi/60 = 21rads/s
6.5 kg.cm = 0.64 Nm

So that motor develops...

Power = 21 * 0.64 = 13W

Google says Kids carts typically use 500W motors and adult carts 1500W.

So way too small.
 

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