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There should be a graphical way of tracking battery usage on a per application basis.

Mobile systems have had this functionality available for quite some time.
IOS - http://c3.thejournal.ie/media/2014/09/b ... 30x471.png
Android - http://blogs-images.forbes.com/jaymcgre ... 5x1940.png
Windows Phone - http://assets.windowsphone.com/9aec2f6a ... efault.png

Possible research : tlp - http://linrunner.de/en/tlp/docs/tlp-lin ... l#features
powertop - https://01.org/powertop

This is quite a challenge. The per-app battery estimate on those platforms is inaccurate at best. It's true that users like to have some numbers to read even if they are meaningless. However, this in the past was not KDE's approach.
Data per-app is there: average CPU usage, powertop wakeups (assuming one can get them per-app...) and disk access are all one needs to guess a power usage. It's not like it's impossible, but it needs lots of fitting to the specific hardware involved, thus lots of time, thus will probably never be implemented.

For example, the battery life estimate was purposely removed from the battery notification plasmoid because it was inaccurate by nature - there's no way it will become accurate, ever, as usage scenarios can change every second. I for one criticized that choice, but I honestly do not miss it that much.