I may be under the wrong assumption, but I thought once the LiPo pack reached a certain voltage the ESC would cut it off.

We recently my son and I got LiPo batteries for our Stampedes. We plugged in the batteries and turned on the LVD on the ESC's. I had a part break on mine, so I didnt get to use it for long. On my sons, it kept full power for a long time, then all of a sudden got really slow. At that point we just stopped and unplugged the battery. Is this how its supposed to work?