I’m looking into the possibility of using the 25D 20.4:1 gearmotor to balance an inverted pendulum with a moment wheel. I’m concerned about the recommended 25% stall torque limit.
I want the pendulum to get upright on its own. To do this I’d need the motor to spin up in one direction and then brake and turn the other way to get the pendulum fully upright. This would generate a current spike of 5 Amps for 0.4 seconds. After the startup sequence the motor would stay wel below 25% of stall torque and it would have plenty of time to cool off.
My question is for long I could have the motor run at 5 Amps without damaging it.
Are there any other factors I need to take into account to not damage the motor or gearbox?
It sounds like you saw the warning on our product page, which I am quoting below for anyone else who comes across this post:
The listed stall torques and currents are theoretical extrapolations; units will typically stall well before these points as the motors heat up. Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. The recommended upper limit for continuously applied loads is 4 kg⋅cm (55 oz⋅in), and the recommended upper limit for intermittently permissible torque is 8 kg⋅cm (110 oz⋅in). Stalls can also result in rapid (potentially on the order of seconds) thermal damage to the motor windings and brushes; a general recommendation for brushed DC motor operation is 25% or less of the stall current.
In general, quick, infrequent transients like the one you are describing should be ok for this low-torque gear ratio, and I don’t have any specific concerns or suggestions about your particular application as you describe it. Just be careful to avoid prolonged stalls (e.g. on the order of seconds), which can result in thermal damage.
Please note that we’d love to hear how your project goes if you do try it with our gearmotor, so I hope you’ll share some updates with us!
