The charger fan turns off once the current going into the battery pack goes below a certain value.
Since the battery pack charges following a CC-CV curve, it’s difficult to predict the exact SoC value, as that can slightly vary.
The bigger advantage is that, once the charging is complete, whenever the vehicle restarts trickle charge, the fan used to kick-in and was an annoyance to people nearby and users who had their pods installed closer to their living space.
Something you had also brought up earlier.
Now, once the charging is near completion, the fan shuts off and doesn’t keep turning on and off through the night