AccuBattery is an Android app that gives battery usage statistics and more detailed readouts from the OS w/r/t battery condition and charge/discharge behavior.

Their help portal has a research summary explaining their sources (the most recent of which is from 2010, so battery tech has likely improved in some respects but it's still a useful reference point): https://accubattery.zendesk.com/hc/en-us/articles/210224725-...