If a LiPo cell discharges below 3.0v, it's very likely damaged. Recharging that cell presents a serious risk of fire. LiPo's no joke and you shouldn't fool around with it if you don't know what you're doing.

I found these two resources particularly helpful bringing myself up to speed:

All You Need To Know About - LiPo's
Endless-sphere.com ? View topic - RC Lipo series charging tutorial

The boards at endless-sphere have more info and are more active than the electric bike board here on bikeforums. I read everything I could find before building my battery and I still made a mistake buying a charger that couldn't handle the 5Ah 6s LiPos. When all was said and done, my batteries cost about $275 to set up and build and then I spent that again on a charger and power supply.