[Samsung Epic 4G Touch] RainMotorsports:
Now tell me this, because I can prove this quote wrong ALL day long, every day. Check your laptop battery. Whats the current capacity? Whats the rated capacity NOT the same are they? If this was true your battery would NEVER charge to 100% again after even a few days of ownership. Batteries lose capacity, never have the rated capacity to begin with. I mean maybe you intended to include that in your argument but you didn't.

Batteries do not hold electrical energy, they also do not have a constant capacity like a gas tank. They can use electrical energy to cause a chemical reaction that stores chemical energy and they can use chemical reactions to turn chemical energy into electrical energy. They still have the same contents charged or discharged. Defects in materials affect design capacity, the chemicals do experience wear or unideal formations.

I googled and well this mac came up :p I dont feel like firing up my laptop.

The charge controller in the battery, yes not the phone or laptop, reports the battery stats. Thats its own problem and then yes the operating system itself can also introduce its own problems. 100% is the current guesstimated capacity of the battery. Current capacity of the battery. Yes I just accused an electronic device of being programmed to guesstimate. Can be done with an amp-hour meter or by checking voltage against previous references, etc but whatever method its usually a cheap compromise. But 100% changes in value to compensate for wear. If I deep discharge my laptop the capacity will go down, a few charge cycles later it will "return" a little (not the problem we are discussing). I can do this with any laptop in my house, but once again not what we are discussing.

Under various load and unload cycles the measured capacity can go both up and down, usually down but not always. Which is the problem I have always had with my laptop the bios fails to report changes to the capacity to windows and i get things like 98% and 101%.

Couple more things. I guess you never had an older car (I had a 66 Austin Healey) that you killed the battery trying to start only to come back later and start it? I mean that battery no longer had enough potential energy to turn the starter and the motor right? I wonder what happened there? There is an explanation for it and no the battery did not magically charge, the chemical energy was always still there. As far as car gas gauges go most modern cars actually delay changes in reading to avoid slight changes in float level from registering. My tank being a really odd shape if fuel is pushed to the front or the back of the tank the level in the direct center actually changes until the situation corrects itself. I always though they should put a sensor on each end of the tank and average it but it still helps to have a normal shape tank.

If you operate a battery in say winter freezing conditions you can have a shorter experienced run time. Only to have energy appearing to "return" after the battery has been returned to acceptable temperatures. Batteries to not magically store electrons. They convert one form of energy to another through a chemical reaction. Current voltage versus the last full charge voltage and the cut off voltage is a quick cheap way to get an idea of how much potential energy is available but this has a curve to it. Measuring by Amp-Hour is preferred. But that won't stop the battery from reaching a low voltage under a wrong condition and the device shutting down.