QGroundControl says battery disconnected when arming

PX4 Autopilot
1

I have a hexacopter with a Pixhawk 6C Mini and Holybro PM08 power module.

Whenever I arm it, it says the battery is disconnected and the battery status icon shows ‘OK’ not a percentage. When I disarm it, the battery remaining percentage reappears again.

If I disable battery failsafe, the hexacopter flies well. There is something about the arming process that is causing the flight controller or power module to indicate there is no battery voltage.

I have set up the PM08 exactly as the holybro docs says to with the voltage divider and amps volt set.

any help is appreciated. thank you

2

Can you set SDLOG_MODE to log from boot and get a log of this behavior?

3

Hi @JulianOes
Sorry for the late reply. This problem has been coming and going and I have been trying to narrow down the cause, but not having much luck. If there is anything you can suggest to help I would be very grateful.

Please see link to log file in flight review and screenshots. This was done from a test inside, so there was no gps lock, but the QGC in disarmed state says battery 100%, as soon as I arm it, it says battery disconnected.

Link to log file: https://logs.px4.io/plot_app?log=13a0574d-6e1b-4464-861d-19819f8e5f37

Screenshot of QGC in disarmed state (battery correctly showing 100%)

px4-disarmed-state
px4-disarmed-state1754×879 211 KB

Screenshot of QGC in armed state (Battery shows OK, but battery monitor shows charge, battery disconnected error showing)

px4-armed-state
px4-armed-state1754×879 213 KB

4

Is this log with the power module connected? I don’t see the voltage of the battery. I only see the 5v from USB.

5

@JulianOes
HI, thanks for the reply. Yes this is with the power module attached. I have been testing this on and off. It appears that with the USB and the power module connected, PX4 reads the voltage as +60 volts but gives a low battery warning if I try to arm it.

If I disconnect the USB, when I fly the copter, the readings are normal. It measures the voltage as expected and gives warnings at the correct times.