VAIO has provided Battery Aging Display function, and the value of battery aging is estimated. So the information of battery aging doesn't mean users have to replace the battery.
The value displayed is for reference only.
The run-time of battery shortens due to usage and aging.
Thus, even when users use a fully charged battery, its run-time will shorten.
Even if users occasionally use the battery, it will become aging and cannot work properly.
Therefore, the battery should be replaced.
In addition, battery duration highly dependent on battery usage, and the way in which the battery was maintained.