Thought it would be worth mentioning this as I have almost lost a heli and a fpv plane as a result of this issue.
I purchase turnigy 3s 2200mah's from HK and have now had 3 of them fail due to the soldering between the wires and the xt60 plug not being secure. A few days ago I was fpving (all electronics off one battery) and when i Landed i noticed i lost all video. The bumpy landing had been enough to dislodge the ground wire from the xt60 plug! On another occasion I was about to take off on my trex 450 and it just suddenly stopped working (another poor solder). Thankfully both failures have been while the aircraft have been grounded. The third failure was during charging.
Have i crashed with these batteries? No, so the problem could not be due to harsh treatment.
So i can only assume it is a manufacturing fault.
Have since removed heat-shrink on all my lipos and re-soldered the connections. Other batteries seemed OK but at least I know I won't have anymore surprises.
Haven't checked, but given the poor quality of soldering to the connecter, I wonder how well the three cells are soldered together?