Is there a way to stop using the backup lipo if voltage drops too low?

[marcmerlin]

I'm a bit worried about forgetting to unplug the lipo one day and killing it.

Also, I found no canonical documentation on this module. Is there one, and for instance an idea of how long a 500mAh 1S lipo would power the module before it dies?
(as in how quickly do I have to find my lost model before the battery dies)