Intelligent charger for 9V NiMH rechargeable batteries V1

I looked for smart charger chat can charge 9V NiMH battery in couple of hours and didn't found one. Moreover all chargers I found was really "dumb". Charging current unknown and no function to terminate charging after battery fully charged. Problem with such chargers that they can overcharge battery and significantly reduce lifespan. So I decided to create "smart" charger using Arduino.

First version I intend to keep simple, so it allows basic things like charging with constant current, autom