Ed:
You are correct. This is also called an "automatic detecting cut off"and this setting is set as the default on many escs. The problem with this is that if your battery is not fully charged it will still cut the voltage at 2/3 of what ever it was at start-up. This could let your battery over discharge and damage it. Most escs can be programed to cut off at a set voltage per cell (either with a transmitter or program card-you would have to have the manuel for instructions).