just now i have the Problem for the 2nd time during the past week.
I am on Insiders fast ring btw.
normally it works fine. same charger all the time.
if quick charging works it should Charge about 1.5% per Minute.
now I Need about 2 minutes for 1%.
The battery wasnt draining fast, have no Special apps running in the Background..
edit: I plugged in the device first, after that I connected the charger to the power. maybe that caused a Problem!?
now I reconnected the phone to the charger and it started to Charge very fast immediatly...