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Old 12-05-2014, 05:13 AM   #76
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Originally Posted by howardcano View Post
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.

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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





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Old 12-05-2014, 11:43 AM   #77
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Dont modern dynos use hydraulics for the measurements now? I thought i read that somewhere
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Old 12-05-2014, 02:09 PM   #78
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Can the Gforce be used to set timing on a motor????
Terry I have one on order you can fondle it in person, in a bit.
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Old 12-05-2014, 04:19 PM   #79
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Terry I have one on order you can fondle it in person, in a bit.

KOOL thanks....
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Old 12-05-2014, 04:23 PM   #80
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Dont modern dynos use hydraulics for the measurements now? I thought i read that somewhere
You mean for real cars and heavy machines? Quite likely. Not sure though how you could use that to make a simple RC motor dyno for measuring Torque vs. RPM.
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Old 12-05-2014, 05:22 PM   #81
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using slave motor to simulate load

http://s42.photobucket.com/user/bpal...9.jpg.html?o=1

http://i42.photobucket.com/albums/e3...pscb489f0c.jpg
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Old 12-05-2014, 07:42 PM   #82
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I see Trinity sells these now. Not sure if they have the updated ones or not.
Any ETA on getting stock in at EAM?
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Old 12-05-2014, 10:36 PM   #83
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I see Trinity sells these now. Not sure if they have the updated ones or not.
Any ETA on getting stock in at EAM?
Should have some more in late next week.

Thanks
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Old 12-05-2014, 11:49 PM   #84
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You probably shouldn't rely on those wimpy clips for doing more than 5-10 amps, or your data will be erroneous.
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Old 12-07-2014, 06:30 PM   #85
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Got to drop my good novak 25.5 motor on one this weekend. i dont remember the rpm's but it pulled about 2.5A the was 2045 and the timing was set on the sticker at 45` and it measured an average of 49` the stator was 47/48/50. pretty close but could be better. dropped my trackstar 17.5 on it also and was pretty disapointed in the results. not going to run that motor again. lol. watched another motor got checked and it was almost perfectly timed and the stator was almost dead on. pulled good amps too. going to have to buy one of these soon.
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Old 12-08-2014, 10:10 PM   #86
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I see Trinity sells these now. Not sure if they have the updated ones or not.
Any ETA on getting stock in at EAM?
I just got the Trinity one in the ail today and it goes up to 70 degrees of timing.
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Old 12-09-2014, 02:02 AM   #87
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Nice, is that your set-up? What Resistances do you use on the slave motor, variable? Also, what is your aim in measuring there exactly, motor's Current load as function of RPM?
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Old 12-09-2014, 10:12 AM   #88
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Nice, is that your set-up? What Resistances do you use on the slave motor, variable? Also, what is your aim in measuring there exactly, motor's Current load as function of RPM?


At this time it is a 19t brushed motor that i use only to simulate some type of a load. I feel better about not free wheeling my motors,and I am more interested in what my motors do under a load . I can also get voltage output from the slave motor as well but I think that may be a little redundant given the numbers i can get off of the dyno. I also wnat to change the A B C wiring on the dyno to get rid of the gator clips and to run the same gauge wires as what i run on my esc. Any input is ..as always very much appreciated.
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Old 12-09-2014, 10:26 AM   #89
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I don't like checking without load so what I do is just leave the motor in the car with the tires on and I check it that way you get a more accurate reading. Checking the motor with no load for me does not do anything.
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Old 12-09-2014, 10:40 AM   #90
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Originally Posted by bpalmer View Post
At this time it is a 19t brushed motor that i use only to simulate some type of a load. I feel better about not free wheeling my motors,and I am more interested in what my motors do under a load . I can also get voltage output from the slave motor as well but I think that may be a little redundant given the numbers i can get off of the dyno. I also wnat to change the A B C wiring on the dyno to get rid of the gator clips and to run the same gauge wires as what i run on my esc. Any input is ..as always very much appreciated.
The only thing that I can think of would be the QTEC power terminals that Reflex sells. It's the only thing I can think of that gives a nice solid connection that would be quick without having to solder every time.

https://reflexracing.3dcartstores.co...nals_c_76.html
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