The minimum voltage business is pretty simple - you shouldn't let the voltage fall below 3volts/cell since that may cause damage. That's the reason there is a minimum to start with - lipo when overdischarged below 3v/cell can swell - literally, puff up like a balloon. Once a cell has swelled up (its called puffed), the lipo is unsafe to use or try to charge. In this puffed condition, lipos have been known to suddenly fail - they sorta vent, release a lot of smoke, get very hot and maybe cause a fire.

The better quality lipos tolerate overdischarge better than the cheaper ones. You may get away with overdischarging an Orion to 2.9v/c where a lipo of lesser quality would puff.

Hope you get your charger prob resolved.