I have several USB Power Banks.
They seem to work fine with most devices. However, they do not work with my Samsun Galaxy cellphone for reasons unknown UNLESS I use a particular USB power output adapter. I must use THIS one for it to charge my cellphone…When this blue one is plugged into the power bank and then the charging cable is plugged into the blue power meter, it works partially ok. But even with this blue adapter, the current output seems to fluctuate all over the place showing for example .27mA one second then .003 the next, then .004, .16, etc and it keeps bobbling around like this. But at least for the most part it charges the phone with this one.
When I plug the cellphone into an AC powered USB charger it charges just fine.
When I use the Power Banks on other devices, they work great showing up to and sometimes over 1amp of current flow to the device being charged.
But no matter what, I can’t get the Samsung cell phone to charge when plugged directly into the Power Banks unless I first plug in the blue USB port tool above. It doesn’t make sense since the output of the USB power bank is 5v + just like the AC powered device.
I also have this USB voltage / current tool (shown below) but I can’t get my Samsung phone to charge when it is plugged in no matter what.
I have several of these and they all are like that. They work fine on other devices but not with my Samsung cel phone.
I don’t understand why I have to use the blue USB tool just to get my PowerBanks to charge my phone?