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I am working on a project where we I have a 24 V battery controlling an electrical system. Attached to that 24 V battery are four 24 V brushless motors. I also have to run two 12 V motors. Currently, I have a 12 V DC Buck Converter to step down the voltage from 24 V to 12 V for the 12 V motors. However, could I cut my weight by powering the motor controller (which is rated for 36 V) off of the 24 V battery and just programatically running it at 50% power to power the 12 V motor?

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  • \$\begingroup\$ Yes, if your motor controller supports it. \$\endgroup\$
    – Eugene Sh.
    Feb 6, 2017 at 21:06

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Yes. A PWM motor controller is a buck converter: an additional buck converter would be redundant. With a reasonably efficient motor controller, the system is likely to be more efficient since the losses from the buck converter have been eliminated.

Just don't burn up the motor by driving too much current through it, for too long. The resistive losses in the windings generate heat which will eventually burn off the wire insulation or cause mechanical failure. Current in excess of the motor controller's specifications can also overheat the controller. This is true regardless of the battery voltage, but a higher battery voltage makes it easier. Many motor controllers have a current limit feature for this reason.

Brief periods of high current, or even 24V applied directly to a 12V motor are not problematic as long as the motor doesn't overheat or exceed its mechanical limitations.

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  • \$\begingroup\$ So is this a valid configuration? Will it damage the controller / result in any inefficiencies? \$\endgroup\$ Feb 6, 2017 at 21:10
  • \$\begingroup\$ @Theodore_Kim Yes, it's valid. See edits. \$\endgroup\$
    – Phil Frost
    Feb 6, 2017 at 21:23

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