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Old 12-05-2014, 04:13 AM
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Dr_T
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Originally Posted by howardcano
Strangely enough, free-running amp draw also doesn't change much with voltage. Frictional and hysteresis losses are approximately linear with RPM, so 1/2 voltage will give about 1/2 the power loss. Since the voltage has already been halved, the current will remain the same to give 1/2 the power loss.
Interesting read here guys, I really like posts like this that help understand the principles behind electric motors, thanks Howard.

Originally Posted by EDWARD2003
Since this motor checker generates numbers under no load, is there anything we can attach to do to produce a load? Have the motor connected to a.......?
I don't race, but I have been looking for a "real" dyno set-up too for measuring output Power (T*omega) of PMDC motors up to 1/5 scale; haven't found any ready made solutions for it. Some guys use a flywheel set-up, but I'm not a fan of it and you won't be able to use that directly with a motor analyzer like this, as you need to carefully register acceleration as funtion of RPM, in order to derive Torque as function of RPM. Best bet for a proper dyno seems DYI-ing a de Prony brake of some sort:

http://my.voyager.net/~jrrandall/Pro...ronyBrake.html






Last edited by Dr_T; 12-05-2014 at 04:50 AM.
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