Charging slowed to a crawl?

My Hisense 7" tablet has charged from 22-25 up to full or 100 in about 3 hours ever since I bought it in June. The back was warm when charging. Well, today it decided to slow to a crawl. In 5 hours today it has charged from 20 to 24 on a 0 to 100 scale. Back is very cool. Charger was checked on another device and works OK. Tablet shows it will be charged by 2 Pm the next day. From the way it has charged in the past, that is nuts.
Any idea on what has gone bonkers? Unit is still working.

 

As I stated, "Charger was checked on another device and works OK."
Any other ideas?