Another option, with an ESC that doesn't provide a BEC, is to use a timer with a regulator chip that converts the battery voltage to the 5 volts needed by the timer and the connection to the ESC. Examples that I provide are the FM-2R, the FM-6R, the FM-7R, and the FM-9R (with the last requiring the FM-9 Programmer). The two leads to the regulator are connected at a convenient point to the black and red wires from the ESC to the battery.