We had an aircraft crash a couple months ago because our Primary and Backup power to our Pixhawk 2.1 failed (not simultaneously). What I am realizing now which is very scary is there doesn’t appear to be any warning if power is lost on one of the two power inputs. This seems like a pretty critical feature?
i) Why wouldn’t this me implemented in Ardupilot? Is there a hardware limitation?
ii) Is there anyways to tell via telemetry data that both inputs have power?
Besides a warning, it would make total sense that is power is lost on one of the inputs a pre-arm check should catch this.
There are power flags in logging. I’m not yet sure if that info comes through mavlink messages…
Have you got a .bin log you can share?
Can you do bit of a power wiring diagram?
was it a loss of power to the power modules or a failure of the modules ? you can set separate failsage votages for each module but im not sure if there is a way of monitoring the 5v from each of them, you can also add another 5v source to the servo rail for extra redundancy.
@xfacta : Unfortunately the impact was so bad, the micro SD was damaged. I do have a telemetry log, but unfortunately I cannot share it. I did have an expert in the community (developer) look at it though and he was able to tell me:
There was no power on the primary input during the log, only on the secondary.
There is no sign of failure in the log, so the power must have disconnected abruptly
I was using a Mauch PL 4-14S / 2x powering both primary and secondary inputs. I will be perfectly honest I was always worried about how hot this unit got, but after confirmation from the vendor it shouldn’t be an issue I kept it in. I actually bought a 2nd unit just to confirm but it got just as hot.
@geofrancis
I’m confident no wiring failed/disconnect in flight as everything was well secured and protected Furthermore, even after the crash the wiring was still in tack and worked fine (multimeter check).
I will never know for sure, but I am fairly sure both regulators just failed over (a long) time because of heat. When I took apart the regulator after the crash, I noticed that on the top carbon fiber plate of regulator it looked “burnt” above the primary regulator. Part of the reasons I can’t conclude the regulator failed in the air was it was crushed slightly during impact. The aircraft does use a RFD900 (powered directly from the FC which I know is not recommended) but it was never set above 100mw which based on specs the regulators should have been able to handle. There are no other power drawing devices (besides a Drotek GPS onboard).
At the end of the day, for all I know the primary regulator could have failed months before. I guess my assumption that there would be a warning if power was lost on one of the inputs proved to be costly. Like I mentioned before, it’s distressing there is not a warning for such a critical component.
+1 To adding a MAVLINK message/error if power is not connected to Port 1. Maybe this is a parameter that we can add - MIN_POWER1_VOLT and MIN_POWER2_VOLT?