Sad day. After good trials with original battery, very easy loiter mode, stable, gentle landing... real pleasure.
Today I changed to spare battery (Turnigy Multistar 5200 mAh 3S 11.1V). Switch on, proper blanking green, but as soon as I give some throttle the Iris jumped approx 20m in the air and started to run straight like crazy. Impossible to follow. Lost.
Do you think only the battery change could have done that ?