I’ve heard a lot about ESC fires occurred with quadcopters. I would like to share my experiences with a pixhawk quadcopter which was assembled a few days back. To be honest, nearly all the parts are shoddy clones ordered from Aliexpress and Banggood. I flashed the pixhawk 2.4.8 with Ardupilot Copter 3.6.9 firmware from mission planner and did all the mandatory hardware setup.

I have never attempted to fly a multirotor before. So it was really challenging for me to control my quadcopter. I crashed it several times even in stabilize mode. Scared of government regulations, all these test flights were carried out near my house only. I survived first few crashes without any significant damages to the quadcopter; only a few scratches on the frame and plastic propellers.

Next time while attempting some hard manoeuvres, the quad accidentally made contact with a tree and fell upside down losing control. I tried to put the RC transmitter throttle down and yaw left for disarming the copter with no luck. I found some motors raising its speed. Then smoke and fire started coming out. Since it was my first experience, I misunderstood it as a Lipo battery fire. So I was scared to go nearby, fearing an explosion. After all the smoke and fire got extinguished, I disconnected the battery. Found one ESC completely burnt, radio receiver antenna damaged and melted and one of the arms of F450 frame burnt and deformed badly.

Now, the mistake was certainly from my side. While trying to disarm the copter, in fact, I wasn’t moving the throttle down completely. That means I was giving a yaw command to the copter. This made the motors to accelerate with blades in a blocked condition. The result was the corresponding ESC fire due to over current. I don’t know why, but the motor survived.

The burnt ESC was replaced with a spare one, damaged frame arm renewed, ran ESC calibration again. Later the quad was taken to an open area. There other flight modes such as Althold, Loiter, Circle, Brake, Land, and RTL were tested. All these modes were successfully tried out. While attempting the AUTO mission, quad flipped over on the ground and burnt another ESC. I disconnected the Lipo battery connector, but this time I lost both ESC and motor. The motor was not turning freely, saw burnt insulation in the windings, suspecting burnt windings due to over current. See the pictures below.

Apart from the two cases above, there was another incident of ESC and motor fire during optional hardware testing in mission planner. I need to check the motor spinning direction with the ‘MOTOR TEST’ in mission planner. The ‘TEST ALL IN SEQUENCE’ method initialized. I was slightly touching the motor with my finger to feel the direction of rotation (which was a bad idea). Felt the rotations of first and second motors, the third one did not turn, smoke started emitting from both motor and ESC. Suspecting the same reason, blocking motor, over current and bhooooooom.

The lesson learned is, anything that obstructs propeller or motor even for a few seconds may result in ESC and/or motor overload and consequent damages. I don’t know the matter with high-quality ESC and motors. My motor cost $6 and ESC cost $5. Also, the ‘MOT_SPIN_ARM’ parameter in mission planner is set to zero so that the motors stop as soon as throttle stick drops to zero.

The quad is ready now. I need to test AUTO flight mode again.