It already exists. E.g. The Dell laptop I currently own already has it as part of some or other pre-installed software.
Time to write an app to do that (possibly only for rooted phones), someone?
That's assuming that devices don't already operate in this range of SOC within device...which I wouldn't believe to be true.
Yes, I didn't (/don't) know about that. I believed the charging cycle would have become intelligent by now, but thought then this whole thread wouldn't come up if that was the case.