Recently I noticed that it takes forever to recharge using the OEM adaptive fast charger. It takes 3.5hrs with slow and 2hrs with fast.
When I plug in another Samsung charger (ie. from S4) it charges within 1.6hrs. Strange enough, when I swap the USB cables, charging time is significantly reduced. I tested this to find out if my cable was to blame. I did this test many times, but I couldn't figure out why.
My main question is, the micro-USB cable going with the AFC is different that a normal micro-USB (ie. from an S4)?

 

I have timed charging times and the results indicate that there must be something unique with the AFC micro-USB cable. It doesn't seem like a mechanical defect with the cable and/or connectors. Just to give you an idea:
1. AFC with its own cable: 3.5hrs
2. AFC with another cable: 2hrs
3. Regular charger (S4) with the AFC cable: 2hrs
4. Regular charger (S4) with another cable: 1.6hrs
Results are confusing I know, but it seems that there is something unique with the fast charge micro-USB cable.

 

That was my guess too, since I cannot explain otherwise. Both cables seem fine, data exchange with both works with no problems.