I built a quadrocopter with Mini APM Pro , firmware 3.2 , S500 frame, 2212 - 920kv motor, 1045 carbon prop, esc 30A, gps u-blox neo7. I tried several flight modes and it worked perfectly. RTL was returning to home beautifully. It was 10th flight and some weird happened to her in air about 20m high. It suddenly had fallen down as an apple from the tree with PosHold mode.
According to APM, Vcc was 4.6v continuously, battery was 10.4v. According to Frsky Taranis telemetry battery voltage was 11.2v , X6R RX was 4.6v.
Do you think APM Vcc 4.6v might have been the culprit of the crash?
Copter was operated with 3S, 4000mha. Although APM is configured for 2200mAh. Does the configured battery capacity make a difference?
@jociz,
Please provide tlogs and/or dataflash logs to help troubleshoot your issue.
Regards,
TCIII GM
I have added the tlog to the original message.
This is the result of Auto Analysis for 2015-08-16 18-21-12.bin:
Log File C:/Users/joci/AppData/Local/Temp/tmp6F94.tmp.log
Size (kb) 4006.88671875
No of lines 51742
Duration -1 day, 23:23:29
Vehicletype ArduCopter
Firmware Version V3.2.1
Firmware Hash 36b405fb
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = UNKNOWN - No ATUN log data
Test: Balance/Twist = GOOD -
Test: Brownout = GOOD -
Test: Compass = GOOD - No MAG data, unable to test mag_field interference
Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = GOOD -
Test: GPS = GOOD -
Test: IMU Mismatch = NA -
Test: Parameters = GOOD -
Test: PM = GOOD -
Test: Pitch/Roll = FAIL - Roll (-132.75, line 51328) > maximum lean angle (45.00)
Test: Thrust = GOOD -
Test: VCC = [color=#FF0000]WARN - VCC min/max diff 0.38v, should be <0.3v[/color]
Result of previous flight coming before crashing flight:
Log File C:/Users/joci/AppData/Local/Temp/tmpE20F.tmp.log
Size (kb) 1339.265625
No of lines 17347
Duration 0:03:24
Vehicletype
Firmware Version
Firmware Hash
Hardware Type
Free Mem 0
Skipped Lines 0
Test: Autotune = NA -
Test: Balance/Twist = NA -
Test: Brownout = GOOD -
Test: Compass = FAIL - COMPASS_OFS_X not found
Test: Dupe Log Data = GOOD -
Test: Empty = GOOD -
Test: Event/Failsafe = FAIL - ERR found: FS_BATT
Test: GPS = GOOD -
Test: IMU Mismatch = NA -
Test: Parameters = GOOD -
Test: PM = NA -
Test: Pitch/Roll = NA -
Test: Thrust = NA -
Test: VCC =[color=#FF0000] FAIL - VCC below minimum of 4.6v (4.578v)[/color]
As far as I can assess from Log Browser, current draw fell down to almost zero while the ThrOut was 100%, ThrIn was above 50%. Maybe wiring harness , ESC, power distribution board is the culprit!?
Any clue for this crash would be appreciated. Otherwise without knowing the cause, it is not worth rebuilding this copter with APM.
Do you have a 3dr power module in your setup?? What other accessories are you powering along with the APM, are you using telemetry also? Maybe a separate UBEC just for the APM and GPS…
Sent using recycled packets…
3dr power module is connected to APM. GPS + compass and 433mhz telemetry are connected to APM.
No other BEC or UBEC are used. Solely 3dr pm supplies the 5V.
I forgot to mention that 3dr supplies the Frsky X6R receiver and smartport voltage telemetry sensor.
I had vcc issues before with telemetry feeding a minimosd. It all worked fine without it. In the end I resulted to powering the APM with its own UBEC. I am running 6s so I have an AttoPilot 180 instead of the 3DR power module. Have you flown without all other accessories besides the ext comp/gps??
Sent using recycled packets…
No, I have not flown.
I am going to replace the broken arm, propellers, 433 radio antenna, GPS mount and damaged motor(s).
I will put an UBEC driving the APM and check how the Vcc voltage will shape.
Now my biggest concern is what I see in the log: "[color=#4000FF]current draw fell down to almost zero while the ThrOut was 100%, ThrIn was above 50%[/color]"
It seems to me perhaps there was a power contact outage between PM and distribution board. The ESC did NOT have power. I am not sure at all but I am thinking of it as a possibility.
As far as I can see from the altitude change, it was not a Vcc brown out.
Still analyzing log and found out the Desired Alt followed the real Altitude while copter was falling down. 
Summing up:
- Vcc was ok before crash and during crash
- Current came down near to zero
- ThrottleIn about 500 , Throttle Out went to 100% and falling after current reached the zero
- Alt and DAlt were at much the same value while it was falling
Can someone give any explanation or have a guess how come this might happen or may cause this weird crash?