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Unread 19-06-2014, 22:34
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Re: Motors: Past and Future

Quote:
Originally Posted by Richard Wallace View Post
Sean has this exactly right. I am becoming more confident that he will be able to keep the Martian colony infrastructure operating smoothly, when the old timers of my generation are in our rocking chairs.

Just one point to add: power available from a motor falls off rapidly as the internal parts (i.e., brushes, armature windings, and magnets) get hot. This happens faster if the motor is smaller -- so even if a fan-cooled (e.g., 775) motor is nominally rated for more peak power than a totally enclosed non-ventilated (TENV) motor like a CIM, the TENV motor will deliver more power in all but the most intermittent of applications. Bottom line: stick to CIMs for your FRC drivetrain (duh).
I wouldn't say that as a blanket statement. Teams have been using 775's/FP's in drives for a long time. In 2003 and past, several of the Einstein teams, like 111, used non CIM's in drive, as you could only have two that year. Pretty much every team with swerve did the same Plenty of teams have also ran 2 CIM + 1 775 drives, like 254 and 118, which are both very successful teams.

With the available current monitoring feature on next year's PDB, stalled motors can easily be detected. It is true that a 775 will burn up quickly when stalled at 12V, but it can last a significant amount of time at 6V.

A minicim weighs 1.5 lbs more than a 775, and is less powerful. Given 1.5 lbs, I could add a decent heatsink and fan to a 775 for roughly the same total cost, and have more power.

Also, a more powerful 775 would be really useful in climbers/hangars, where you (ideally) never stall.