Vapcell S4 Plus V3.0 Power-Bank Function !
I tried a new simple test on my Vapcell S4 Plus V3.0 in power-bank function - mode, with two Samsung 50E 21700 batteries, full charged, in slot 1 & 4, the phone was down to 28% !
After 2+ hours, yes i was using the phone all this time, the phone is 100% charged up, and the charger is at 60%, and everything is normal, no heat on the charger or on the batteries, no smell, no smoke no nothing !
For me there is no reason to afraid to use the power-bank function - mode (when you really need it), is working just perfectly !