Copter can't throttle up (need help with log)


I just finished a quad copter build using a Pixhawk, F450 frame, E300 motors/ESCs, 3s battery, Taranis X8R receiver.

Today I went out to fly 2 batteries. Later on the 2nd battery’s flight, the copter starts descending (given my initial throttle down input), and no matter what I did on throttle channel, it just descended, quite abruptly. Looking at the flight log (download here: gives me no clue of what happened, it only confirms what I just described. It felt like the motors couldn’t handle the copter weight somehow.

I’ve been flying a hexacopter based on Pixhawk and E300 motors/ESCs and this never happened.

I can’t confirm exact weight but it should be around 2kg with all gear plus battery installed.

Can somebody help me understand what happened?

Log file:

Log screenshot:

P.S. Another thing that happened before first flight was that after powering on the pixhawk, the status led blinked red and blue (police pattern) , I went to mission planner and noticed that I had no RC input readings. It got fixed after 2 power cycles.


Forgot to mention the lines (10^3):

  • around 67 it is visible that I’m throttling up and the altitude decreases
  • around 82 the same thing happens with even more amplitude.


I have the same issue like’s your too. Just the other day i flew my iris+ with a fully charged battery for about 3 minutes then the copter start to descending and crash. No matter i push the throttle up all the way it won’t go up. Do you solved the problem yet?