I believe that probably not one person on this forum has actually tested the time it takes to charge a battery.
I would very much like to be proven wrong.
You can buy an inexpensive USB test meter that will read out the voltage, current and certain other data of the USB ports in your vehicle and elsewhere. The device has a male USB-A plug on one end and a female USB-A socket on the other end.
The original one was called Charger Doctor and they are usually the cheapest available. There are newer, more expensive versions available that are far more sophisticated, almost like mini plug-in multi-meters and have multiple types of inputs.
One cool feature that many of these have is a built in timer that also records the amount of current that has been transferred during the timed period. So, if you plug one of these devices in the path between a power bank and a charger it will record the amount of time it took to charge the battery bank and how much current capacity it took to fully charge it during that period.
Over the years I've done various tests timing how long it takes to charge Li-ion battery banks of different sizes at different levels of discharge along with using chargers with different current outputs, so I guess I can prove you wrong on your speculation about no one testing charge times. Obviously, standard lithium power banks are different than an "It's Cell" but I run dash cams and action cams off of power banks on a regular basis so testing charging times has been part of the process.
Some of us long time dash cam owners here on the forum wouldn't be with one of these as an essential dash cam accessory.
The Keweisi shown in the photo has the following specs. For a few dollars it's probably the best bargain for a basic one of these.
Specification :
Voltage :
3V-9V, ± 1%
Current :
0-3A, ± 1%
Timer :
0-99H
Battery Capacity :
0-99999mAh
Size : Approx. 7.2cm x 2.2cm x 1.1cm / 2.83" x 0.87" x 0.43"
Here you can see the timer (T) and capacity meter (in mAh) at work.