I experienced an unwanted erratic flight after carrying out some changes to my drone. I updated the firmware from 3.04 to 3.06 and also changed the video output channel on my Immersion 5.8G transmitter in an attempt to improve a somewhat noisy FPV output. Prior to this the drone had been flying flawlessly and I was blown away by the fantastic video quality from the H3 3D gimbal and Go-pro setup. In an attempt to rectify this erratic flight behavior I carried out all the necessary calibrations including an IMU reset. The next flight was also erratic and I began to believe that I was about to suffer a dreaded flyaway! The drone just wasn't responding to any stick inputs from me and then descended rapidly at low level and crash into a corn field. Thankfully no damaged occurred and I prepared the drone for its next flight minus the now removed gimbal/camera and transmitter. When I hooked up the RC to the system assistant software to again recalibrate it I noticed that the battery voltage had dropped from 4.6v to 4.3v. I believe that the threshold alarm voltage is set to 4.2v and not once prior to this had I ever heard the RC low battery alarm. The only alarm that I had heard from the RC was the "no sick activity" after 15 minutes. Armed now with new batteries in the RC my drone responded to stick inputs again and flew properly again. The changes that I carried out were obviously a red herring call it Sod's or Murphy's law which led me believe these were somehow responsible for the erratic behavior - cause and effect etc. However it might be prudent (certainly in my case) to check the RC battery voltage on a regular basis! I'd be interested to know if anyone else has suffered similar erratic flights because of a low but not out of limits RC voltage? Also next time I'm changing the RC batteries when they reach 4.6V!