Monday, July 5, 2010

By The Numbers: ESC

The ESC (electronic speed controller) is used to control  the speed of a brushless motor.  It usually has a BEC ("battery elimination circuit") to provide power to servos and the other receiver outputs.
  • Continuous Current -- how much current can pass through the ESC on a sustained basis.
  • Burst Current -- how much current can pass through the ESC for a short "burst" of time (usually 60 seconds).  If you exceed this time, you will probably burn up the ESC.
  • BEC (battery elimination circuit) -- How much power is available to the servo and other receiver outputs.
  • Cells-- the voltage and type of battery supported.
  • Weight: QED
  • Size: QED
  • two input wires from  the battery
  • three output wires to the motor
  • three-wire bundle to the receiver.  two wires power the receiver (including passing power to the receiver outputs), one wire is the control wire receiving the throttle control signal.
ESC Programmer: some ESCs can be programmed.  This can be done via the receiver (by "clicking"  through entries using the joystick) or more easily with an ESC programming card ("no more black magic throttle stick controls!").  Typical  programmable values are:
  • brake -- on/off.  stops the motor immediately when throttle is cut, used for feathering props.
  • battery type -- battery voltage, or "auto".
  • cutoff type -- gradually reduce or immediately shut off power when the voltage threshold is reached.
  • cutoff voltage -- 2.6V, 2.85V, or 3.1V per cell.
  • start mode -- normal, soft, very soft.  helis use soft, planes use normal.
  • timing mode -- low, medium, high.
  • music -- for some inexplicable reason, you can program the esc to play different songs at startup.

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