[Epic 4G General] chaosfenix:
The thing to recognize, as has been pointed out in several other posts, is that GWCarpenter is talking about the actual service life of the battery and Plap and others are talking about the "effective life" of the battery as indicated on your device.

To answer the question in the quote: As referenced in another post on this thread, the phone only gets information about the "effective life" of the battery when the battery is fully charged or when it is out of power. I say out of power here because [I believe - please correct me if this is wrong because it is what the remainder of this is based on] the phone receives the signal when the phone shuts itself off the first time. (Which is where you want 0% to be, any lower and you damage your battery.)

I don't think anyone (in this thread at least) is saying that you should then turn the phone back on and run the battery down until it is *completely* out of juice - all of the information presented from both camps says this is bad thing and should be avoided whenever possible.

So when you reset the battery stats and your battery is full, the device now has a starting point that it calls 100%. If you let it run down until it turns itself off, it now also has a stopping point it calls 0%, and can now relatively accurately indicate what percentage of "effective life" you have left at any given time in between.

However, if you only reset stats when it is at 100% and then keep recharging it before it hits zero, the device only knows how much power was used but has no way of knowing how much power was available. As the car & drinking glass analogy tried to point out the device has no way of knowing what percentage of battery has been used if it only knows that the battery was "full" when it started. The device does not know whether or not you have a 1500mah battery in it or a 2500, it just knows that it was "full." Consequently without a second data point for empty, all it knows is how much energy it has used, but it cannot put a percentage to it without that "battery empty" data point.

Another car analogy: Say you borrow your friends vehicle for a road trip but the fuel gauge is broken and you know neither the capacity of the tank nor the expected fuel economy of the car.

You have two choices:

A) Fill the car up and let it run all the way down so you know how far you can go, or

B) Go a certain distance you arbitrarily feel comfortable with then fill up the vehicle, repeating until you reach your destination.

With option A you can accurately gauge your fuel consumption and the remaining quantity of fuel in the tank and how far you can get on a full tank. (This is the fully charge / discharge (the safe discharge that is) method for those playing the home game.)

With option B you know nothing other than that you can go the arbitrary distance you chose to travel. You know the fuel tank is never empty at that point, but you cannot say how much you have left in the tank, i.e. fuel percentage remaining.

(This is what happens if you only do the fully charge / wipe method.)

Again, the argument has not been about what is best for the actual service life of your battery; it has been about how to get your device to accurately represent the "effective life" provided by a fully charged battery. Similar terminology for both without differentiating the two has caused the problems in this thread.