Hi Coleman, I’ve a 300RPM 12V DC motor and its specifications are as below,
30kgcm torque
No-load current = 800 mA, Load current = upto 7.5 A(Max)
I’ll be using a 12v, 28 AH battery, but the load current of DC motor is 7.5 A max. so can I use this battery with the mentioned motor without any damage on motor? and how long this motor can run with one full charge? and can I use this motor to convert my city bike to e-bike? total weight would be 80 kg ( Bike + Person ).
@Venkatesan That’s a really big battery. The motor will only draw the current it needs, so it should be fine.
Which motor shall I choose for my combat robot having 10-12 kg weight. I would be using 4 motors.
i. 4x 200RPM 10kg-cm motors or
ii. 4x 60RPM 15kg-cm motors
It looks like 15kg-cm would be better choice as torque matters in robowars and speed is not really that much of my concern. But I don’t know if 60RPM would be enough to start the robot.
@Deep Ode It’s difficult to determine the “best” motor given the range of conditions which a combat robot will face (being pushed by another robot, traction concerns etc.). We do not have any questions to present to you, but you can follow the guide here and add an additional force (from another robot) to the equations: https://www.robotshop.com/blog/en/drive-motor-sizing-tutorial-3661
Good day sir, we have a project called jar tester(6-paddle stirrer) and i just want to ask what motor you can suggest since we have decided to use dc motor, the output speed required is (25 rpm, 100 rpm, and 250 rpm) ,we are using a belt drive system and we really don’t have idea about electrical components. And also, if i may ask, how can we vary the speed of the dc motor electrically speaking? thanks ahead sir.
What is meaning of rated speed mentioned in most of the datasheets provided by motor companies?
If i want 20 rpm at the output of the motor, when operated with nominal load, should i design the reduction ratio according to no load speed (lets say it is 7000 rpm) or rated speed (lets say it is 5000 rpm).?
@Cj Take a look here: https://www.robotshop.com/blog/en/how-to-make-a-robot-lesson-5-motor-controller-3695 Regarding particular motors, you would need an idea of the torque and nominal voltage.
@Usman The “rated speed” tends to be the rotational velocity (in rpm) of the motor when it’s subjected to the “rated load” (torque). Essentially, how fast the motor will turn under normal resistance.
@Usman If you want it to rotate at 20rpm, you should really consider using a gear down, not simply lowering the speed of a non-geared DC motor. You would choose based on the rated speed.
I have a load whose weight is around 500 kilograms, mounted on a circular aluminium rotating platform, like lazy susan. this platform has teeth and will be connected to a worm motor. my question is, I dont need high RPM. 4 - 10 seconds only to rotate 4 degrees is fine. what’s the min torque I need? 30 Nm enough? any other spec of the motor I need to know about? is that enough to also counter the friction aside from the inertial moment of rotation? thanks
hello, my question is very simple… which motor driver is suitable and can support for four motor power window?
@Joseph You will need to do some calculations for friction (static and kinetic) and inertia. There are no “back of the napkin” calculations we can provide.
@saddam You need to know the specs of the motors (voltage and current) before you can choose a motor controller. Normally these are 12V (because a car battery needs to power them), but range in current consumption (est. 250mA)
are motors with torque ouput above 50Nm common? are they considered high torque? thanks
@Joseph That would be used for medium sized robots. What is considered “high torque” depends on the application. If you want to make a small mobile robot, 50Nm is high torque.
Up to which value I can go for a DC motor for nominal current 110% … 150%, thank you in advance 
@KEZIH Normally current is not described as a percentage. Would 100% be stall? If so, you should only operate at around 25% stall.
how do I calculate the power of a motor given that the speed of motor is 30RPM? Thanks In advance
@khazie You need more than just the speed. Ideally the easiest way to calculate power is Power = current x voltage.
