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Unread 09-01-2012, 02:13
theprgramerdude theprgramerdude is offline
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Re: Official 2012 Motors Models and Specs Thread

Quote:
Originally Posted by Andy Baker View Post
These numbers, posted by me on the AM website two days ago, are not correct. They have been updated to much more realistic, and larger numbers. We at AndyMark are changing these numbers a bit after some further testing this weekend. Sorry about this change. Please check our PG71 web page for any further updated information.

Here is more to the story.

When I was updating the web page for this motor on Friday, getting it ready for Saturday's kickoff, I saw that the stall torque was listed at 11 amps. This is information we got from the manufacturer. So, I called Mark, who was out at Manchester for kickoff to see what was up with this. He created and interpreted the performance numbers a few weeks ago, and listed the stall torque at 11 amps. We both thought about this some more and agreed that was waaaaay too low. He got home today and did a bench test that repeatedly performed at these numbers below. This test was ran with a 12.8 volt battery providing voltage directly to the motor. The stall torque is 23 ft-lbf, and the max current reading is 28.6 amps. We believe this translates to approximately 350 watts as the max power for the motor.

Tested at 12.8 volts
23 ft-lbf max torque at stall
28.6 amps pulled at stall
Estimated 350 watts of power

Here is Mark's setup. He had a force gauge measuring an arm's pull at exactly 1 foot away from the motor. The force gauge showed 23 lbs of force and the amp meter showed 28.6 amps. It was a simple setup, and we ran it about 10 times. The numbers were consistent. These numbers make much better sense to me compared to the "11 amp stall torque" numbers I posted on Saturday.

Again, sorry for these erroneous numbers yesterday, and please check out the PG71 website for future updates.

Sincerely,
Andy Baker
I don't know if I'm doing this right (actually, I'm pretty sure I am), but if you input 28.6 Amps at 12.8 Volts, that's equivalent to 366 watts of electrical power being put into the system.

350 watts of output power translates to >90% efficiency for a 12V motor, something that is ridiculously high.

Or, maybe I'm reading this wrong, and you're simply stating that it can pull about 350 watts of power, and not the output power... I'm confusing myself.

In the retest, was the torque due to the arms weight accounted for?
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Last edited by theprgramerdude : 09-01-2012 at 02:15.
 


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