Quote:
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Originally Posted by sanddrag
Torque is directly proportional to current.
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Sanddrag et al,
This would be the case if there weren't so many other variables in the system. Please remember, that unless the speed controllers are at full throttle (I don't recommend this except for short bursts) any current measuring you would use is likely averaging the current supplied to the motor. Remember that the controller outputs a PWM signal except when at full throttle. Each device will use a different method of trying to average the current so the results are really inconclusive under normal operating conditions. Averaging varying pulse width, fast rise time signals, with a complex component as a load is a daunting task for designers. Add to that the different brush/commutator designs, production variations, temperature induced resistance changes and transmissions losses and one can see that relying on current to torque conversions will become misleading. Dave's method is a simple, ball park approach to aid in design.