paper: 2009 Motor Data

[kramarczyk]

Thread created automatically to discuss a document in CD-Media.

2009 Motor Data by kramarczyk

[sanddrag]

Where is the Banebots 545 specification from? It is significantly different than the specification provided on this page.

[Kevin Sevcik]

The quantities aren't correct either. There's two FP motors in the kit, as usual.

[Tristan Lall]

The RS-545 data there is for an older motor supplied by Mabuchi. The 2009 RS-545 motor is similar-looking, but not manufactured by Mabuchi, and has different specifications.

Also, I was playing with the spreadsheet, and noticed that the "At max. efficiency", "Normal rated load", and "At max. power" rows don't do anything, and actually only contain information for one particular motor.

And I'm not exactly sure what's going on here, because BaneBots lists K_v = 1400 rev/(min·V), which works out to K_e = 0.00682 V·s/rad. The spreadsheet calculates K_v = 0.006529 V·s/rad. Similarly, BaneBots quotes K_t = 0.0079 N·m/A, while the spreadsheet returns K_t = 0.00581 N·m/A. (These constants affect pretty much everything.) I had a quick look at Mark's math, and it looks right, so I'd have to guess that BaneBots may not have the correct values for something. (But are their given speeds, currents, etc. correct, or their constants?)

[Kevin Sevcik]

The motor curves generated by this spreadsheet aren't correct. Or they're only correct when you have the reference voltage set to 12V, or whatever the reference voltage was on the data sheet. Changing the reference voltage doesn't change the max current, stall torque, max power, or generally anything that it should. The "calculated" motor data the plots are based on doesn't calculate the stall torque from Kt, V, and R, it only looks it up from the motor data table.

I think this spreadsheet should be considered a beta version at this point, as there are more than a few things about it that seem inaccurate.

[kramarczyk]

Originally Posted by Tristan Lall

The RS-545 data there is for an older motor supplied by Mabuchi. The 2009 RS-545 motor is similar-looking, but not manufactured by Mabuchi, and has different specifications.

I was not aware of that, thanks.

Originally Posted by Kevin Sevcik

I think this spreadsheet should be considered a beta version at this point, as there are more than a few things about it that seem inaccurate.

Yeah, at this point it is clear that I bungled this one... nothing for me to do now, but fix it. Thanks for the feedback.

[kramarczyk]

I totally forgot about this needing to be worked on. I'll get on it.

[kramarczyk]

Updated in 2010 version at http://www.chiefdelphi.com/media/papers/2320?