By Katie Marsal

Published: 06:00 PM EST

Apple said Friday it has discovered that some batteries used in its MacBook and MacBook Pro notebooks may have performance issues and is offering a software update that is designed to improve performance.

The 244KB Battery Updater will check to see if a battery needs to be updated on startup, wake from sleep, and when a battery is inserted.

"If in these cases there is no AC power supplied, it will then wait until AC power is present and then check to see if the battery needs to be updated," Apple said. "If the battery needs to be updated it will update it automatically. Wait 30 seconds before you validate the installation."

The update supports essentially every MacBook system produced by the company thus far, including: MacBook, MacBook (Late 2006), MacBook Pro (15-inch), MacBook Pro (15-inch Glossy), MacBook Pro (15-inch Core 2 Duo), MacBook Pro (17-inch) and MacBook Pro (17-inch Core 2 Duo).

Apple notes that after Battery Update has been installed, each battery inserted into the MacBook or MacBook Pro will be updated automatically.

If, after installing the battery update, the battery has any of the symptoms listed here, Apple urges MacBook owners to make a reservation to bring their computer with its battery to a local Apple Retail Store, or contact an Apple Authorized Service Provider (AASP), or call a local Apple Support Contact Center.

If Apple or an AASP determines that a battery is eligible for replacement, MacBook owners will receive a new battery, free of charge, even if their MacBook or MacBook Pro is out of warranty.

The repair program extends repair coverage on the battery for up to two years from the date of purchase of the computer for Intel Core Duo-based MacBook and MacBook Pro computers.

Apple said it will continue to evaluate the battery update program and will provide further extensions as needed.