A curious question... :) I tried to charge this with a low-watt charger, to see if it would accept it. I have an old 5V/0.7A mobile phone charger I kept for this kind of test. With a microUSB to USB-C converter, it seems to work, however, it would take a long time to charge. Do not believe it has a good IP rating, maybe it would be better to select a power bank with a good IP rating for use outdoors.