Without a battery, laptops such as the Sony VAIO will not work, even when plugged directly into an outlet. Therefore, if your VAIO operates, the battery is viable. To check the charge, you will need to boot the computer into Windows first.
Connect the battery to the Sony VAIO.
Plug the AC adaptor into the laptop and a power outlet.
Turn on the laptop and log into the operating system.
Look in the status bar in the lower right corner of the screen for an icon of a battery. It will also include a picture of a plug, indicating it is currently charging.
Roll the cursor over the battery icon in the status bar to display the battery's charge percentage.
For maximum battery life, let your battery fully discharge once in a while before recharging. Consider having another VAIO battery on hand for emergencies.