Matthew007

I know I have not read or posted anything here in a long time and needed to re-register (forgot my ID ) since I bought my Traxxas Bandit but was hoping you guys could help maybe.

I need a dyno to measure amps, voltage, and rpm to measure the output power of a motor. If I can measure torque and rpm i can also calculate the power output.
The power input I can easily measure by obtaining the amps and input voltage.
I'm doing this for an engineering project about changing how the brush/commutator system works on generally high performance DC Brushed motors. My goal is to reduce the friction of the commutator system, make the "brushes" last much longer and provide minimum arcing through relatively available limits of pressure (of the "brush" against the com). I'm putting "brush" in quotes because what I want to design will not look like one at all. There will still contact of current through rotating conductive material.

Brushless systems for relatively high drawing current motors (i.e not airplane appliclations) are very expensive.
Of course I will also research why brushless motors in our application (high torque, high current draw -comparing to stuff like air plane motors, computer fans..etc.) to see if it is really the idea of just no brush contact that actually increases performance and/or efficiency.

I'll be dealing with smaller brushed DC motors (around 540-555 size).
I basically need this to calculate the efficiency of a motor and prefferably at different RPMs, Voltage, and loads (amps).
I greatly appreciate your suggestions.
P.S
I would like a limit of under $100.
I am open to making my own.
Also, towerhobbies dont have real dynos, only have use for comparison, and they are very expensive.

Thanks and Happy Thanks Giving!

Marshl

Like this----->
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXJGW4

Dawman

My Feedback: (33)

There are many motor Dynos that do exactly what you want . Look at Integy , Trinity , Orion , and many others make motor dynos .

dirt101

is an eagle tree like a dyno?

Matthew007

Thanks, I made a bid on one just now. I assume I can get it to work with a 555 motor or others with no or few modifications.

However again, It says I can obtain the current in and rpm out. I can do that with a cheapo multimeter and optical rpm monitor. It's good for comparison though. If I missed something where you can obtain the POWER output through just input amps (same as current draw) and RPM then please tell me.

For example in two different motors, If both draw the same current (Amps) and one produced more RPM..it doesn't mean squat until you can get both output torques to see which one is more efficient and has higher power.

I hope I can use a prony brake which I've found out from my professor that we have in the lab.

Update:
I found this neat site on a prony brake:
[link]http://my.voyager.net/~jrrandall/PronyBrake/PronyBrake.html[/link]
Im looking at the bottom of the page and equation.
However, I do not see friction in the equation because correct me if im wrong but it factors out because it is directly related to rpm since less friction allows for more rpm, less pull force on scale and more firction means less rpm and more pull force on the scale. It looks simple enough. My question is: If we order scales, pulley and belt for my small dc motor application, will it give us accurate results? Also, is it possible to let the friction "steady out" becuase of changes in temperature and unfortunately the material property under possible high temperature which hopefully wont occur for ours small applications (540-555 size motors).

Matthew007

It's a shame how they ripp you rc hobbyists off with useless $150 tagged equipment that are really worth like ten dollars.