The battery of a MacBook is, like that of any other laptop, less powerful when he gets older. Unfortunately, it is in MacBooks is not possible to have the battery replaced. An Apple Store may have a replacement run.
How strong the capacity of the battery by the time reverse is gone, it is usually a matter of feeling, but there are also tools to the state of the battery is really transparent. An example of such a free program is CoconutBattery.
CoconutBattery is a free tool for the MacBook that the battery status can be checked.
You can both the history and the current status of the battery. This is not only to the time that the battery will last, but also the temperature and the amount of time that it is charged.
With the online service CoconutBattery Online you can select your battery capacity compare with that of other users.
CoconutBattery has the following characteristics:
CoconutBattery screenshots
You can free download CoconutBattery 32, 64 bit and safe install the latest trial or new full version for Windows 10 from the official site.