Sorry another lipo question

[speed demon]

The min volts for my lipo is 3v per cell. What does that mean? I mean when?....under a large draw or at rest? I was out playing around and noticed my truck slowing down alot so I stopped. I quickly checked it and it was 16.0v. I gave it 15 min and rechecked it and it was 16.4. I went to charge it and the cells were all about 3.25ish and the volts shot up to 17.9 only after a few seconds of charginging. Am I ok? Does all sound normal? Thanks.