How to properly calibrate an iPhone 3GS?

[neonbright]

This is from Apple website for the iPhone.

Use iPhone Regularly

For proper maintenance of a lithium-based battery, it’s important to keep the electrons in it moving occasionally. Be sure to go through at least one charge cycle per month (charging the battery to 100% and then completely running it down).

 

[thelatinist]

I implore you to explain why the Apple laptops require a five hour discharge while the iPhone calibrates with an instant discharge?!

That's an easy one. They don't. They require either that you allow your computer to sleep for five hours or that you turn your computer off. This is because as the battery reaches empty, the computer doesn't actually shut off, but goes into sleep mode. The computer maintains a reserve of power to keep your phone in sleep mode for several hours. Because of that, the battery will not be calibrated until the computer actually powers down. That resets the charge meter.

No such sleep mode delay exists on the iPhone. The only reserve maintained by the battery circuitry is the reserve required to prevent battery damage. The iPhone completely powers off when the battery is discharged, and the charge meter is reset at that point.