[Galaxy S II General] nrk_2k:
I would not suggest this as it is a very good way to kill your battery. I will give you guys some facts about Li-Ion batteries, and dispel some of the myths that are floating around XDA (& the web).

First off the battery (well more correctly the chip associated with the battery) CAN NOT be re-calibrated on our phones. The only thing you can affect is how the ROM/Kernel interprets the information the battery gives it.

You should also never let your phone fully discharge, as this is the absolute worst thing you can do to a Li-Ion battery as it causes instability within the batteries molecular structure. In fact, keeping the battery above the 10% mark at all times is probably the best way to prolong battery life.

Giving the "battery" a few cycles after flashing a new ROM/Kernel to let things smooth out (or however you want to put it) has always puzzled me as to where this came from. Flashing a ROM/Kernel does nothing to the battery (or the chip associated with the battery). If the BatteryStats.bin file was erased during flashing then battery history will be lost and that's it. Reboot's of the phone are more likely to "smooth" out battery life than charging "cycles". Li-Ion batteries have a very linear lifespan (they will keep the same output all the way until they suddenly die), so every charge "cycle" is the same output wise for the battery. If it seems to drain faster from one "cycle" to the next, this is most likely a usage (apps, hardware, or user usage drain) rather than anything to do with the battery itself.

The chip associated with the battery is built into the battery itself. In this way it is always powered. The only time it is not powered is when the battery is dead. This is why when Li-Ion batteries die they will no longer charge, as the chip does not report back to the charger, and so the charger stops supplying current. Much like how the charger stops charging once the battery is full (it will flick on and off to keep the battery at 100%, which is why sometimes it will say fully charged, then when unplugged may only say 98% or something like that.

Instances where a huge battery loss is noted after a reboot or power off/on and then the battery level "mysteriously" increases is most likely caused by a temporary issue with the batteries chip. Many things can cause this like temperature difference, or just the chip getting itself caught up. This is unfortunately a downfall of mass-manufacturing, but does not affect battery life in any way. The chip should output the correct level after it clears itself up again (the mysterious increases).

There are many weird and wonderful side effects that come with "smart" batteries. And while technically the method stated in this thread actually achieves nothing, the "placebo" effect that it has is well worth giving it a go anyway. So long as you don't let your battery fully discharge it wont do any harm either.

Just keep in mind that the above applies to our SGS2 devices specifically. Some other phone models have batteries whose chips can be re-calibrated which is where I would say all the talk of doing it for our phones came from ;-)

One last thing, before the haters start flaming me for dispelling myths.. I am a trained electrical engineer that has spent the time researching and working closely with different battery technologies, and am only offering these facts to help you. I am not trying to attack anyone or call them liars, just wanting to offer up the facts for people :)