Source.

I've often found myself explaining why people line the walls of airports and libraries with their laptops. So maybe this blog can be of some practical use. Maybe these four bullets could reduce stress in your life and give you a good conversation piece at parties.

Guidelines to keeping your battery healthy:

1. Run the battery all the way down before charging.
2. Turn the device off to charge it.
3. Charge it all the way.
4. Don't leave it plugged in after full charge.

These are especially important the first few charge cycles of a battery's life. Afterwards it's best to do these things whenever possible. Obviously, sometimes this isn't possible - as these are mobile devices. But the more you follow these points, the longer your battery will last.
This goes for cells, laptops, cameras, gameboys...

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