The Direct Drive Brushed Option

Discussion in 'Propulsion' started by SteveT44, May 11, 2017.

  1. SteveT44

    SteveT44 Well-Known Member

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    For those that aren't ready to make the jump to brushless motors or hate messing with reduction gears, I wanted to throw this out there. Brushed direct drive can work well with power and torque comparable to other setups. The secret is to bump the voltage to 18v or more and run the RS555PH motors. My Barham is equipped with the 555 motors running on 24v and direct driving 1.5" props. This combination has torque and power to spare and ran three days at the 2017 Spring regional without issue. The system was so powerful that I had to dial the endpoints down to 60 percent to make speed. This setup has also proved to be energy efficient. After two sorties (using the same battery for both), the 8AH 24v SLA pack only lost one volt. That included running the pump (which is also running a 555 motor).

    The caveat with a high voltage setup is the speed controller. Most hobby grade ESC's will burn out if fed this much voltage. The good news is that there are options from the robot combat world for simple and rock solid controllers that will easily handle 24v. If your good with a soldering iron, must hobby grade ESC's can be converted to 24v operation by simply removing the 5v voltage regulator chip (the onboard BEC).

    There are many ways to get more power out of a drive system. If your sticking with low voltage, those solutions are reduction gears or brushless outrunners. If your willing to explore higher voltages, five pole brushed motors wound for the higher voltages (like the $5 RS555PH) can be a reliable and powerful option.

    Motor: Mabuchi RS-555PH. This is a low rpm 5 pole motor rated to 20v built for cordless power tool applications (runs on 24v just fine). Because it is a five pole motor, it has higher torque (and lower rpm) compared to three pole 540 or 550 motors. http://www.alltronics.com/cgi-bin/item/28M120/153/Mabuchi-DC-Motor-8-18V

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