Why does my iPhone starts charging at a higher percentage than initially displayed?

[xAppleFanx]

why sometimes when my phone says 1%, I charge it and starts charging at 2%. why that happens? because mostly it drops to 1% and it charges from 1%

 

[Just_Me_D]

Probably because the remaining charge was closer to 2% than anticipated.

 

[xAppleFanx]

and how do I make that stop happening?