Originally Posted by
peter9477 The info shown for "time left" is provided by the OS itself, and based on the latest power reading, and the battery remaining. Unfortunately those values update only every two minutes, and in two minutes there's lots of time for conditions to change and make it appear that, instantaneously, the prediction is incorrect.
For example, if you have the screen off and low power consumption, then swipe it on and check, you'll likely see a longish value like "102h left". Given that you have the screen on and its the biggest consumer of power, that's obviously impossible.
Likewise, if you were playing an intensive game, then stop and check the time left a short time after, you'll likely see it saying only an hour or two left, when in fact you'll probably get many more than that if you don't continue the CPU-heavy activity.
The current "time left" value in Battery Guru works best if you check it only after a period of stable conditions, and only if you take into account the fact that the OS updates this value only once every two minutes.
I'm working on improvements for a future update, where the app itself will supply a projected time left rather than relying on the current one the OS is supplying to it.