I have a Jeti Advanced 30 plus , does anyone know if i have got this right

Does the BEC have a cut off point ( voltage ) or am I right in saying that the ESC will cut the motor when it gets to 9volts ( if set for a 3 cell lipo ) leaving the remanding pack voltage for the BEC, but at what point would the BEC stop powering the servos and receiver ?

The reason is that my 1700mah pack ran down quickly ( recharge took 1650mah ) on a landing approach and at 3 feet from the ground , seamed to lose all power/ control so the motor may have been cut due to getting close to the 9 volt cut off point , but what about the BEC for the servos and receiver ?