Hey guys, my buddy lost his bird over water due to a critical voltage auto land. I've noted a few issues to him I've seen in his flight log: HealthyDrones.com - Innovative flight data analysis that matters (Hope that link works) Anywho, a little insight, were in Miami so cold weather not an issue. He is running 1.4 on his P3A. One issue right away I called him out on was taking off at 67% battery. I've done this a few times, heck even launched at 40% after using a battery earlier. Still his battery had time to cool down as it was hours between flights and if I ever decide to use a half drained battery I make sure it's at most 20 min between flights to keep battery warm. Ok so he takes off at 67% gets a critical error at 56% 2~min of flight. I also noticed his battery life is at 87%. He should've discharged a while back to reset or tossed this battery. Other that these obvious issues can anyone explain what happened in cell #4? I've learned a lot about lipos and these "smart batteries" but not sure the characteristics of the cells individually and how they act when battery life goes below 90%. Is this normal activity at 87%? Please take a peek and let me know if you see anything else I've missed. As every crash this will be a learning lesson I want to make sure my buddy and I and anyone who reads this forum not let this happen and be more knowledgable in the preemptive steps to keeping our batteries and birds happy and healthy!