Originally Posted by Tesseract
We have a 250hp marine dyno that uses a gear pump which bolts right onto the propshaft to force hydraulic fluid through a variable restrictor nozzle. It's very elegant and seems to be accurate just going by the electrical power to the motor (factoring in it's published efficiency) versus the pressure/rpm measured by the dyno.
The test stand we use? A block of aluminum bolted onto the rear bearing plate of the motor so along with the gear pump up front it can rest level on the ground
Granted, this isn't a *vehicle* dyno, but Dalardan's characterization is correct: we got the dyno to test controllers, not vehicles. Still, we have already tested a number of other controllers (usually causing us to
hysterically) and have three different motors that can be bolted on to the dyno (WarP 9, Kostov 144V 9" and Kostov 192V 11") so once we wrap up the beta testing of the controller we want do a little motor comparison of all three for the EV community.
My point was auto engine dynos are not friendly to anything but ICE power curves and the mounts are very limited. What you have works great for you and that's what really matters. But for a true testing facility open to public and all their different schemes one needs to have a very universal type mounting system that can have a motor bolted on and ready for testing within minutes. My neighbor with the SuperFlow dyno can take an engine from the back of his pickup to running on the dyno in 15 minutes. You can't spend time fabricating new mounts every time you have a new engine that's why their set up is geared so they can mount any auto engine within minutes, I just wanted the same for motors.
I have thought about the chassis dynos, but there are tons of them everywhere and there's no modifications needed just drive the car on and strap her down. Plus at that point the fitting work is all complete in the car and it's too late to make changes without spending lots of extra time now. I'm more concerned about getting the components matched up ahead of time and maybe testing other combinations with components I have in the test cell ready to go.
The best dyno that I can think of is the eddy current dyno, very controllable and super accurate. We use this type of dyno for any and all certifications such as emissions on ICE. The downfall is their cost, or should I say the controllers cost. I just got a quote today for a refurbed unit with all new controls at $70K. The up side to them is I could test any EV motor out today and most that haven't come out yet. It has the ability to hold a WarP 9 or 11 or 13 at 500 rpm at full tilt amperage. There isn't a water brake dyno built that can do that.
Like someone pointed out before it's about learning the limits of your given set up. When things are going to start going bad according to what temp etc. . We could do what we call in the dyno world as life cycles. We could program a complete real world scenario of hills and fast areas and stop and go for as long as needed to satisfy your curiosity. http://www.youtube.com/watch?v=8DYl4mD_620
this is a Honda F1 engine running a life cycle test that is programmed into the computer to simulate an entire race so they know before it ever hits the race track that it can at least survive a race. I think putting an EV motor through it's paces on a dyno will show a few things that we may otherwise miss.
This is taken from another thread to use as an example of the questions that could be answered, this was from Bowser330,
...When looking at the motor graphs, Amps decrease with RPM, so with a locked ratio this means, the faster you go (mph) the less Amps you can pull from the pack...So can you please help me understand how the dragsters like S10-smokescreen and the White Zombie can extract max amps for 11 seconds?
I guess i was under the impression that they could only extract max amps up to a certain rpm...
If it is because those two example dragsters have high voltage setups which push up the overall rpm curve, then I guess i understand...
Also i am assuming that the motors still have a structural maximum rpm of about 6000 before they break apart...Is there a way to increase that? END OF QUOTE
I would love to say, that's a great question. Lets bolt up a motor like theirs and controller like theirs and see what happens. And while were at it let the whole world watch along on a web cam. I used to love watching real time dyno testing online. It keeps you informed and lets others watch along and maybe help out as I did with the dyno web cam I speak of. I was listening in during a test session and heard them trying to figure out what fuel line to use on a high pressure 250 psi fuel line so I picked up the phone and dialed the dyno shop and gave them the part number of the stuff they were wondering if it existed.