I brought a used battery for my P3A from a member on rcgroups for $80. I marked it as used so I would know which one it was. I was filming a wedding and was using the battery and it gave me a "battery cell" warning area ( 1st mistake). I was still in the middle of filming and figured hey I'll bring her down at 20% (2nd mistake) ...I just finished and brought her down and 1 ft from the ground she turned off and luckly just tipped one of the props in the dirt! Thank goodness it wasn't a long flight I would have been screwed!. I will never buy a used battery again!