LG G2 slows charge rate with time

[AC Question]

i have a 5V 2A samsung charger and a high-quality 3rd party usb, when i plug in i get around 1450-1670 mAh which is good, but after few minutes plugged in and while using it, the rate goes down to only 309 mAh, sometimes even less. Im using stock lollipip 5.0.2 in the VS980 and its also rooted. So, is there anything i can do about this? because i dont have the original charger.

 

[Rukbat]

First, the current going into the battery (to charge it) is the current coming out of the charger minus the current used by the phone. (Ampere will show you how much current the phone is using if you don't have the charger plugged in.) If the charger is capable of 2 Amps on a single port, there's no reason the phone can't draw 1450-1670mAh from it, whether it's the original or not. If the battery is near full charge to begin with, the charging current will drop once the battery reaches about 4.3 Volts - it's supposed to.