I have recently puchased two of these portable chargers and so far I love them. In the official user manual it states “Fully charging your portable charger from 0% battery level should take 10-13 hours.” Further goes on to say “Please note: The portable charger can charge a device while being charged at the same time. However, when charging a device simultaneously, the portable charger will charge more slowly.” Also in the manual it states the inputs allowed to charge the portable device. “UBS-C 5V/2.4A, IPhone Lightening 5V/1.8A”
I hope this helps!