Re placement battery only charges very slowly with OEM fast charger

[Android Central Question]

Just received my new V20 extended battery 6800mAh from TQTHL. Install went smoothly BUT since it was only 57% charged I attached it to the fast wall charger that came with my phone. It started that it was either not connected correctly or I needed to use the charger which came with my phone. (My battery that came with my LGV20 was fully charged in an hour and a half from 15% !) Is there a fix for this or another charger I should buy?