Switching off during a non-stop-recording

I plan to use one of my AudioMoth for on-side non-stop recordings (Going on-side, use audio-chime to switch it on, leave it there for multiple hours and then come back and turn it off).

I am unsure how and when the audio files are written to the sd-card. Is the current file still written before it turns off or is there a danger to lose the entire recording if it is shut off while recording. Furthermore, Is the file split on longer recordings or will it be one giant file?

Thanks