[ausev] Motor dyno, was: GE 11.5 inch motor

[Chris Robison]

Willie McKemie wrote:
>> This is a good question in general. I'm wondering how hard it would be 
>> to build a dyno...? maybe with water and some vanes swishing it around 
>> or something. Eh, just another distraction I guess. What's unfortunate 
>> is that neither Netgain nor Warfield (their manufacturing partner) have 
>> a dyno that's large enough to fully test their larger motors at 
>> realistic voltages and current.
> 
> A big centrifugal water pump with a choke valve on it's outlet would 
> certainly make a good load.  It might be possible to make some power 
> estimate by measuring the flow and the temperature difference between 
> inlet and outlet.
> 

Cool idea, if you could achieve something approaching accuracy. I'm 
concerned that it wouldn't be able to build up enough pressure though. 
Centrifugal pumps or fans are good at pushing against backpressure, but 
not really at the pressures I'd think would be necessary. Something like 
a gear, scroll or piston pump might make a better load against an 
adjustable orifice. Maybe with a pressure sensor, and some way to 
measure output flow (and probably temperature as you mentioned). Maybe 
if you blocked the centrifugal pump completely, you could make the 
device measurement exclusively thermal.

Torque curves are really important too, though ... and my searches so 
far have found that shaft-to-shaft torque sensors are really expensive, 
on the order of many thousands of dollars. Maybe we could wait for a 
cast-off on eBay, maybe one that's lost its super-accurate calibration 
or something.

I'd look now except I'm at my mom's house in the boondocks of extremely 
southern Alabama, connected through bluetooth and a cell phone with one 
bar, and eBay is timing out before showing anything.

   --chris