Bat.volt, bat.voltr, Fvas -- different voltage values?

While checking a recent log using the excellent plot.dron.ee site, for a flight when I had a battery failsafe condition, I noticed there are 2 named values:
bat.volt & bat.voltr which are approx. 1 volt different.

I can see the FasV voltage on my radio which is provided via Frsky passthrough telemetry.

I am running 3.6.11 on Pixhawk/Chibios with a Mauch PM.

Can someone pls explain the origin/meaning of these 3 voltage values and why they would not all be the same?

Battery voltr is the estimated resting voltage. This is calculated from the estimated battery resistance. The resistance is calculated by seeing how the voltage drops with current draw.

The voltage you see on your pass through telm is probably the raw voltage.

1 Like

So the voltr value is not much use when flying :slight_smile:

Which voltage value is used by the flight controller when comparing with the battery failsafe minimum and does it need to below that minimum for a particular length of time before it triggers the action e.g. RTL?

I think some people of are of the view that it is more useful because it reduces the voltage sag that would happen due to a sudden throttle increase for example.

There are parameters for that, BATT_FS_VOLTSRC and BATT_LOW_TIMER

http://ardupilot.org/copter/docs/failsafe-battery.html#advanced-settings

Tx for the link to advanced settings. I did not know about those extra params introduced in 3.6.

Ho my friend.i am using a cuav V5 plus in a Vtol and in some of my flights when i do mission,the aircraft start to take of and reach to the take of altitude and when it going to transition to wing,the forward motor start to work snd after 1-2 seconds it stop and the aircraft hover with its quad motors.also the video get freezed and i have to change to qloiter mode.this is one of my bin files when this error happened

And also when i checke the volt and voltR this is the diagram


And also this is my forward motor output

Would you please help me to get rid of this problem?