Our team was looking at using one of these motors for our arm, however there is no 18V on the Power distribution board. Is there any way to power it with 18V or would it cause any problems to run it though the 12V?
There’s been a lot of discussion on this on C/D. Go into the competition manual data for the motor curve. The motor will run fine on 12 vdc, but not produce as much power if run on 18 vdc, which is not available on the competition robot power supply.
Rules state that you need to power it with 12v through the PDB and a speed controller. Running a motor at a lower voltage than what it is rated for is perfectly fine, in fact that is what the speed controllers are basically doing when you turn a motor on at half power (actually a time average of 12v pulses).
Ok thanks. We thought that would be the response, we were just trying to figure out what the torque output on the 18v motor would be at a lower voltage, which the motor curve document told us.
Just an FYI, some RS775’s were defective from the manufacturer and the case was shorted. Here’s a thread with some relevant info: http://www.chiefdelphi.com/forums/showthread.php?t=91733&highlight=775+Case+Shorts
We used two 775’s without any hassles, but some teams had some relatively serious issues because of defective units.
If the motors weren’t defective, they’re great. I love them. A bit more robust than the FP or 550 and they have a pretty good punch.
But case shorts do suck, so we didn’t even try to run ours in the 6 motor drive configuration we built for. We got lucky this year and didn’t play any pushing matches so we were still pretty agile.
Here’s a simple motor calculator which has the specs for the RS-775 built into it. You can get the performance at any voltage:
http://www.chiefdelphi.com/media/papers/2432
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The RS-775 rocks!!!
I have heard the horror stories surrounding them, but as long as they are not in contact with any metal, they work excellently. 2 drove our arm this year. It was awesome.
Same here I home they are here to stay they pack some serious power and they cant handle a stall here and there.
I only have one complaint about the 775, the plate on the rear of the motor needs a little more secure attachment to the motor, but our team COULD just use a screwdriver to notch the sides of the motor. Or, we could stop using a hammer to put press fit gears on motors 