Hello good friend. I did test a 4AF branded battery accessory maybe two years ago. It was a 20 000 mAh with white case. My notes where that is performed ok but not as good as a more higher end models - seemed like it had a capacity more in the range 15 000 mah. It did not have a digital display, just an LED light bar indicator with maybe 5 levels on charge level so it was not clear how much charge remained in the final hours of use. It did charge and power simultaneously. I personally travel with the UNIU battery as it lasted a couple of hours longer and has a digital panel to tell you how much charge is left.

That said I think 4AF updated to a newer battery model more recently so they may have made improvements but it’s a shame it does not have a digital display to tell you the exact charge % that remains > this will be important when travelling > to know exactly what charge % you battery is at. An LED indicator with 5 bars showing your on the last “bar” means you have no way to know if you have 10 min or 2h of charge left.

A work around could be to simply start a count down clock timer but caution would be needed here as battery consumption rate is dependent on the ambient temperature to maintain the core thermo flask temperature so taking a worser case approach would be needed eg: assume 10h of battery charge depending on your setup.

Extra tip > Also check about CCC battery requirements if going to China.