This could be due to the compatibility of that particular phone itself with the charger. I have PowerPort Speed 5 A2054, and it will not fast charge my Samsung Tab S3. I have many QC chargers, and this particular charger is the one not doing fast charge to the Samsung Tab. The Tab will prompt "Slow Charge" instead of normal charge, which is worse still. I switch to IQ port then the "Slow Charge" prompt is gone and normal charge takes place.
This Aukey A2054 QC fast charge every other devices I have (Note 8, S7, Note 4) except for Samsung Tab.
Every other QC fast chargers (Dodocool, Aukey, Samsung Original etc) will fast charge the Samsung Tab except for Aukey A2054.
A dead loop ya?
Today the Tab S3 receive firmware upgrade to Oreo, and now it accepts QC fast charging from Aukey A2054. However, I observed the Reference power from Galaxy Charging Current App is most of the time showing negative mA reading, which indicates something is wrong. no background app running, the battery % does not increase although showing "Fast Charging".
Any other Samsung S3 Tab user to share this?