A quick article here to stop the beeping of your battery alarm on punch outs all the time - especially micros where you tend to get a reasonable amount of battery sag. The battery voltage monitor on betaflight is probably one of the key pieces of information conveyed by the OSD or buzzer but is really annoying when it goes off all the time on punch outs when the battery immediately recovers afterwards. That's because the flight controller samples the battery voltage very frequently and will report on even the most minor dips below set value (0.1V by default).
A really useful tool is to use vbat_hysteresis in the CLI section of betaflight. By default vbat_hysteresis is set 1, which is 0.1V (i.e. alarms if 0.1V less than warning/critical values that you set). I found that by setting this value 3 (i.e. 0.3v) I didn't have the unneccessary warning on punchouts now did I have to compromise the actual settings I like my warning and critical values set at - 3.5 and 3.3V for the record.
For those have not use the CLI in betaflight yet, simply go to CLI on the bottom tab in betaflight configurator. Type "set vbat_hysteresis = 3" <Enter> "save" <enter>, Job done! If you want to revert to default, use "set vbat_hysteresis = 1" <enter> "save" <enter>