Pixhawk 6C Mini Battery Status Dropping Out During Flight

Pixhawk
1

Hi, I’m encountering this issue on the Pixhawk 6c Mini where the battery voltage reading on QGC will randomly drop out and reconnect again mid flight. When on the ground, the battery voltage reading is accurate and consistently shows the battery percentage and voltage on the battery status tab on the main page of QGC so I believe it is not a wiring issue. This issue only surfaces randomly during flight (even during a simple hover) and resolves itself and I’m still able to continue on my flight, except for a few “Critical battery level, land now” warnings. Even when checking on the flight logs post-flight, there is no indication of any loss of data for voltage readings

It doesn’t seem like anyone else has surfaced this issue, but I was told that it might be a “voltage validity” issue where the Pixhawk 6C Mini will only consider the voltage to be valid if the power module outputs >5.05V to the Pixhawk. This is as compared to the Pixhawk 6C where it is only >3.9V. So in the case where there is a voltage drop, the Pixhawk 6C Mini might more easily assume that it is low on battery. I’m unable to find any information about any of this online though so I’m not sure if its an issue with the PX4 flight stack or the flight controller. However, it seems like this issue persists in v1.16.0

I will try to use a power module from CubePilot’s Power Brick Mini and see if that is able to produce a more stable voltage output to the flight controller

Flight Controller: Holybro Pixhawk 6C Mini

Power module: Holybro PM02v3

PX4 Version: V1.15.4

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Flight logs do not show any abnormal voltage readings

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Battery status during flight

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Battery status randomly drops out

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Issue resolves itself

2

That’s odd. Can you share the link to the logfile?

3

Sorry for the late reply! Here is the log file: https://review.px4.io/plot_app?log=ae39b926-bb41-4077-baa0-5b3a9b10b659

I just tried it with a CubePilot Power Brick Mini and it doesn’t have this issue. Here’s the log file if you’re interested in comparing them: https://review.px4.io/plot_app?log=0be6e144-0956-49c4-a30e-e19e16ad5c65

I was told by my colleague that the Power Brick Mini gives out a more stable 5.3V as compared to the Holybro’s PM02v3 but I have yet to use a multimeter to test it for myself. I was also told that I’m able to configure some “voltage validity” options prior to building the firmware file but I have yet to find any leads in regard to this

4

I don’t see any drop outs, I just see that the voltage was critical right after take off, presumably miscalibrated:

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5

Yup that’s the problem. The drop outs are not logged in the flight logs but yet QGC randomly shows that the battery is disconnected at times. I don’t believe the voltage sensor is miscalibrated because the rest of the voltage graph still shows an accurate voltage reading. Regardless, I’ve tried re-calibrating the voltage sensor but the same behaviour happens only while in flight

6

I see. I would suspect something else in your system is sending the battery status message, so QGC gets conflicting information. Is anything else connection to your drone sending messages?

You can have a look in QGC → Analyze Tools → MAVLink Inspector to see what’s arriving.