Battery: EVO Screen's power use; very odd.

[exempli_gratia]

I've found the commonly reported "lasted # of hours" posts impossible to compare. There are just too many variables in individual daily use.

So I've run some tests free from as many variables as possible. No radios, syncing, background processes, etc. The goal is to have empirical, controlled, and reproducible data.

The results look somewhat odd, hopefully others can reproduce and/or have explanation.

Test 1: 100% brightness, No screen timeout, Airplane mode, no radios, no sync, No background processes (kill all visible in ATK), one place/orientation.
Start with 100% battery. Unplug. Run 3-hour timer. Repeat.

Battery Used: 58% (59%, 57%, 59%)
Android System: 76% (74%, 77%, 77%)
Display: 18% (20%, 17%, 17%)
Clock: 6% (6%, 6%, 6%)
Procs auto-started during test: (Astro Player, Google Gestures, a few other built-in's (e.g. Voice Dialer)
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Test 2: 0% brightness, No screen timeout, Airplane mode, no radios, no sync, No background processes, one place/orientation.
Start with 100% battery. Unplug. Run 3-hour timer. Repeat.

Battery Used: 30% (31%, 29%, 30%)
Android System: 77% (77%, 77%, 77%)
Display: 17% (17%, 17%, 17%)
Clock: 6% (6%, 6%, 6%)
Procs auto-started during test: (Astro Player, Google Gestures, a few other built-in's (e.g. Voice Dialer)
​

Analysis:

Screen brightness matters a lot, yet few people talk about it in their results.

If brightness of the screen is such a large factor, why is Display still only ~18% for both the 100% brightness and 0% tests?

If the only thing running is the clock, and that's 6%, what is the 77% "Android System" doing?

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[Kedar]

I put my brightness at 50% at the cost of longer usage.

I feel like the battery usage statistics is slightly wrong. I might be wrong though.