Galaxy S5 charging slowly despite 'AC' and 2A charger I have replaced the battery in my Galaxy S5 with a genuine Samsung (or at least, a very, very good fake!). It's now becoming quite noticeable how slow it charges - when plugged into a Nexus 7 2A charger (I have lost the Samsung original), using a USB ammeter, I can see it drawing around 0.5-0.7A. The ammeter does not seem to interfere, as I also have a mains power meter that shows less than 5 watts being drawn from the wall without the ammeter. My understanding is that the data pins in a charger USB socket are bridged to indicate the phone can draw more current, and the phone recognises it's connected to 'AC' in the battery screen, but it doesn't seem to be pulling the maximum available from the charger. I've tried a combination of different USB cables and some other USB power supplies without much difference in charge rates. I do have a good collection of apps installed, but my understanding is that if an app was draining the battery almost as fast as it was charging, the phone would still pull more power from the mains.

Is there anything else I can check, or am I just going to have to lump it? The phone is running stock Android 6.0 with all current Samsung updates.

Possibly related, but I also have the Qi wireless charger kit with the S View cover. Although the pad also demands a 2A charger, I've only seen the pad draw 0.8A from the adapter, and I know some power is lost in the pad, so I'd be surprised if half that was reaching the phone. I know Qi is slower and less efficient than plugging in directly, but this does seem excessive.
Your understanding and measurements are logical and I can't say why your battery should charge slower compared to the earlier one 

One thing you may try is to backup your device and flash latest stock ROM or custom ROM which has a kernel that permits higher rate of charging

If that's a lot of work, change the USB cable to a thicker one. See my answer here for details

(I am not affiliated with the product but a happy user. I keep buying those when on discount and gift to friends. All have uniformly attested to better charging rate)

Edit : It could be a faulty USB port too. You could try getting that replaced