Planner voltage not the same as log voltage

Using Mission Planner earlier I was watching the battery voltage decrease during flight. A slow gradual decrease to 20.4 displayed on the HUD.

I have now reviewed the log files and the lowest voltage recorded is 21.4. Has anyone else noticed this before?

Why is there a 1V difference between the HUD display and the number that is stored in the log?

HUD voltage is coming from Mavlink SYS_STATUS messages sent by the flight controller. So if it is not a match (which seems an impossible situation), then it is something wrong on the flight controller side.

Maybe it could be a difference between one using the resting voltage estimate and the other using actual??

I can’t remember if that could made into a logging options bit.

Do you have a log for that?
I can take a look whether it is in the messages and logs or not.