I’m getting sudden mid-air power loss on my VTOL in QLoiter. Motors stop and it falls on its nose. Has happened twice with virtually the same logs.
After 60-75s of hover (~27–30A total), all lift motors stop within 0.2 seconds. FC stays on and logs data, no error messages. Lifting motor RCOUs jump up as current drops, so FC tries to keep flying.
Setup: AOS 2807 1400KV, 7x4.2 props, SpeedyBee F405 Wing, F405 mini 35A 4-in-1 ESC (BLHeli_S, no telemetry), 6S2P pack, XT60 and 14 AWG between FC and ESC.
Same issue happened on 6x4.2 props with XT30 and 16AWG between FC and ESC, hence the upgrade to XT 60 and 16 awg. Temps using IR thermometer: ESC and XT60 both at ~48C 1 minute after power off, motors ~60C 2 minutes after. Mag readings precise within ~35 milliGauss and accurate within ~50.
No error messages, no signs of reboot or failsafe.
what is strange is when Q_M_PWM_TYPE was 0, i was still hearing the three ascending beeps on power on for the esc and motors plus the two beeps signaling esc was ready. I had the following params before: SERVO_BLH_OTYPE = 6 for dshot 600 on all motors SERVO_BLH_MASK = 124 for enabling dshot on
s3 throttle pusher motor
s4 to s7 lifting motors
SERVO_DSHOT_ESC =2 to stop lifting motor pulsing.
The motors were able to fly relatively normally for over a minute on both of my power loss crashes. Is this because the pwm pulse signal was ok for that long?
Answered in discord. It’s either a heat or voltage issue. If the parameters are good enough that the motors are flying but then they all stop the problem is most likely with the ESC, or maybe the power to the ESC.
I’ve done preliminary tied down bench testing with props on for 10+s at 20A+ total, close to the hover current needed @23V. No motors are running hotter than expected, but the rear are having to work harder. Probably because the Cg is ~20mm forward of the thrust centerline.
Will rebalance Cg tomorrow morning and retry for 30 seconds, then 90 seconds or longer to see if I have the current cliff issue again.
