Macbook air 13 2013 in battery drain issue This is the second time that battery is causing issue. Initially after I bought I gave it to apple service and they reinstalled OS and suggested VirtualBox was causing the drain so I did not install it next time around. 

Now I installed Intel HAXM and battery again fell back to 3-4 hours. I have removed Intel HAXM and still the battery is giving 3-4 hours.

Activity manager does not show a rogue process, most processes are under 1%.

Can you help me detect why the battery is being drained or how to find the cause? 

EDIT
looks like https://apple.stackexchange.com/a/6301/53842 might have a clue. I did not check on All processes in activity Monitor filter. It was 


  parentalcontrolsd


taking more than 80% CPU. Now the battery is slowly coming back to show more time.

Question part 1> Are virtualization software generally drain life on mac? Or is there an alternative?

Question part 2> If parental control service is causing drain then how do we use parental control feature without draining battery? Many other posts suggest to delete and restart and then use it again.
Using the OEM tools like Apple Activity monitor could tell you who is using the juice.

Open Activity monitor located in your utility folder.

Select CPU

Select All processes

Select %CPU to sort by usage

If any process is using >70% (for longer then few seconds) it is the one draining your battery.