Originally Posted by matttye
Most devices won't let you discharge the battery fully for that very reason. Whilst they show you only have 1% remaining, you probably actually have about 6% or something. The other reason they do this is so that the device can shut down gracefully. You never see a phone just turn itself off when the battery runs out, it always shuts down gracefully with a "shutting down..." blinker or whatever.
The fact that it does not discharge down to 0 does not mean it is good for the phone. These batteries are maintained in the best way if you do not go below 20% before plugging in. The advice, is harmful and if you follow it, you will kill your battery in a few days.
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