A lucky escape 
Most manufacturers quote 2.75V as the “drop dead” discharge voltage for their LiPo cells (though some say 3V).
The discharge curve is very steep at this point so a good idea to aim for 3.3V or so as the cut-off voltage in practice. Also any imbalance between cell capacities is exaggerated at these high levels of discharge, to avoid one cell over-discharging it’s a good idea to use a monitor that checks each cell rather than the whole battery voltage if you insist on dragging every last available mAh out of your LiPo’s…
73 de Paul G4MD
Edit: to bring this closer to the topic title, the equivalent minimum discharge voltage for Lithium-Iron Phosphate cells is usually stated as 2.3V, though some manufacturers recommend 2.5…