Why does my iPhone Keep shutting itself down at 99% battery level?

When my iPhone hits 99% battery level it shuts itself down. The only way to turn it back on is by plugging it back into its charger. I have done multiple restores thru iTunes and it still has the issue. I have also done a replacement to my old battery but this one still does it too. BTW: i have no warranty any more. Any ideas please?