To prolong the lifespan of the battery, we'd better charge it after the battery runs down.

Mavis wrote

To prolong the lifespan of the battery, we'd better charge it after the battery runs down.

Yes Mavis, i know that.
But i need to use it outdoors, away from any city (for astrophotography to be more specific), and if the router ran out of battery is my intention to use a power tank. But i can't stop photography and wait until router is charged; i need to charge the router and use it at the same time ...