title_body: What does BEC, SBEC, UBEC, and OPTO mean for brushless motor ESCs? I'm looking to purchase an ESC to go with a brushless motor. Many of the product pages include terms related to a BEC, such as SBEC, UBEC, and Opto.
  
  What do those acronyms mean and how should I choose between them when selecting an ESC?
upvoted_answer: BEC: Battery-eliminating circuit. Basically just allows you to use the ESC to power the controls circuit, servos, etc. (hence eliminating the need for a battery)
  
  SBEC: Switched battery-eliminating circuit. Just an improved version of the BEC which makes it more energy efficient.
  
  UBEC: Similar to SBEC, just more energy-efficient at the expense of being slightly heavier.
  
  Opto: Uses light (optocoupler) to segregate control and motor circuits, to reduce interference. Therefore requires two sources of power, one for the controls and one for the motor.