iPhone 6 charges extremely slow after reaching around 70% it's now been a few weeks since my iPhone 6 started charging extremely slow after reaching 70% battery life. I am aware of what slow trickle charging is, and the issue I am having is not it. After reaching around 70% my iPhone charges by 1% every 25/30 minutes and even seems to slow down towards the 80/90%. In fact when I tried to charge it to 100% it took me the whole day. I tried every suggestion I could find on the internet, including restarting, resetting, and even erasing all content and settings and restoring the device (not using a backup). I am starting to think the battery has an issue, but just a few weeks ago I had zero issues related to my battery.
Thank you in advance
It should take 4 hours to charge iOS devices with the official supplied adapter when the device is idle or powered off. Healthy batteries should reach 80% in two hours. Then two more hours for the last 20%. 

If yours plateaus sooner, it’s either due to power drain of things running while it charges or a sign that the charger or battery is out of specifications.