# Pre-arm check error “Avionics power is 4.7v” in QGroundControl

Source: https://forum.modalai.com/topic/206/pre-arm-check-error-avionics-power-is-4-7v-in-qgroundcontrol
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2021-04-22 22:11:51 UTC by shlee853
Replies: 4 · Views: 765

## shlee853 · 2021-04-22 22:11:51 UTC

Hi,

I set done for all my flight configuration for indoor flight.

But, I got a message from QGC as “Avionics power is 4.7v”. So, I denied armming.

My battery is fully charged with 4s lipo.

Could you please let me know how to check to release this message?

Thanks,

## Reply by modaltb (ModalAI staff) · 2021-04-22 23:05:28 UTC

Hi @shlee853 ,

What's your power setup look like?   PX4 reads the input voltage (out of the power module).  If the gauge of the wire is thin you could get some voltage drop perhaps.

What's your other hardware setup like (anything plugged into USB?)

## Reply by modaltb (ModalAI staff) · 2021-04-22 23:06:29 UTC

If you have a volt meter, could you read the output of the power module as well?

## Reply by shlee853 · 2021-04-22 23:17:43 UTC (in reply to modaltb)

@modaltb My flight is flight deck with similar m500 frame.

I also used power module provided by modalai. 

I tested my manual flight before downgrade sw.

Yesterday, I downgraded system s/w version 0.3.2 to test VOA feature.

In this case, I cannot pass pre-arm check in QGC.

What does that mean avionics power? Is that VOXL input power?

Thanks,

## Reply by modaltb (ModalAI staff) · 2021-04-22 23:23:45 UTC

The Flight Deck has the two main components (VOXL and FlightCore).  They share a 5VDC rail that is fed by the Power Module on the M500.

The FlightCore portion of the board is a little STM32 microprocessor running PX4.  PX4 reads that 5VDC from an ADC.

Depending on your toolset, it could be easy to probe that voltage: https://docs.modalai.com/voxl-flight-datasheet-connectors/#j1013---5v-dc-power-input-i2c3-to-power-cable-apm

When you did the manual flight you had no issues?