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Unread 04-10-2009, 07:47 AM
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Jared Russell Jared Russell is offline
Taking a year (mostly) off
FRC #0254 (The Cheesy Poofs), FRC #0341 (Miss Daisy)
Team Role: Engineer
 
Join Date: Nov 2002
Rookie Year: 2001
Location: San Francisco, CA
Posts: 3,069
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Re: voltage-torque curve

Quote:
Originally Posted by kamocat View Post
Are you saying that a CIM at full-forward with the battery at 11.5v will perform differently depending on whether the battery is drawn down under load or simply drawn down over time?
11.5V is 11.5V, regardless of how it got to 11.5V.

A CIM will perform differently connected to an 8V, 10V, or 11.5V source than it will to a 12V source. And because our batteries are not ideal voltage sources (they have a built-in resistance) and our wiring is resistive, their terminal voltage will drop under load. So pull a lot of current from your battery (say, by stalling your drive motors) and you will find that your shooter, for example, has slowed down because the effective instantaneous terminal voltage of your battery has dropped.

Effects like this that prompt Al to correctly say that claims of motor response "linearity" are dependent upon many factors besides the speed controller response.

Last edited by Jared Russell : 04-10-2009 at 07:50 AM.