The battery status is defined in com.garmin.fit.BatteryStatus with
4 = LOW
3 = OK
2 = GOOD
When the battery status and battery voltage values are displayed in a chart and when the voltage is declining, the battery status do sometimes display a 2 (GOOD) or is switching to 4 (LOW). This behavior is repeated over several battery replacements.
My conclusion: Do not trust the battery status 2. The states 3 and 4 seems to be OK.
A vertical bar shows the values at the beginning and at the end of one tour.