Some Macintosh computers have a backup battery to maintain system settings, such as the date and time, when the computer is turned off . The battery may last up to five years. However, this varies due to the battery's shelf life, and usage patterns of the computer. The batteries used in Macintosh computers are lithium or alkaline, and are commonly 3.6 V to 4.5 V.
If your computer does not retain parameter RAM (PRAM) settings when it is turned off, this generally indicates that the battery needs to be changed. Some Macintosh models may display a black screen when you turn them on if the battery needs to be changed.
If you are uncomfortable changing the battery, an Apple Authorized Service Provider can install one for you.
Desktop Macintosh Computers
iMac
| Macintosh Model | Battery part no. |
| iMac (Mid 2006), iMac (Late 2006) | 922-6476 |
| iMac (Early 2006) | 076-6476 |
| iMac G5 (iSight) | 922-6476 |
| iMac G5, iMac G5 (Ambient Light Sensor) | 076-1098 |
| iMac (17-inch 1GHz, USB 2.0) | 922-4760 (Note 2) |
| iMac (Flat Panel, 17-inch Flat Panel) | 922-4760 (Note 2) |
| iMac (Summer 2001) (Note 1) | 922-4028 |
| iMac (Early 2001) | 922-4028 |
| iMac (Summer 2000) (Note 1) | 922-4028 |
| iMac (Slot Loading) | 922-4028 |
| iMac (233 MHz, 266 MHz, 333 MHz) | 922-4542 |
eMac
| Macintosh Model | Battery part no. |
| eMac, eMac (ATI Graphics, USB 2.0, 2005) | 922-4028 |
Mac mini
| Macintosh Model | Battery part no. |
| Mac mini | 922-6476 |
Power Macintosh G3/Power Mac G4
| Macintosh Model | Battery part no. |
| Xserve | 922-4028 |
| Power Mac G4 (Mirrored Drive Doors) | 922-4028 |
| Power Mac G4 (QuickSilver 2002) | 922-4028 |
| Power Mac G4 (QuickSilver) | 922-4028 |
| Power Mac G4 (Digital Audio) | 922-4028 |
| Power Mac G4 Cube | 922-4028 |
| Power Mac G4 (Gigabit Ethernet) | 922-4028 |
| Power Mac G4 (AGP Graphics) | 922-4028 |
| Power Mac G4 (PCI Graphics) | 922-1262 |
| Power Macintosh G3 (Blue and White) | 922-1262 |
| Power Macintosh G3 (Desktop, Minitower, All-in-One) | 922-4542 |
Portable Computers
iBook
| Macintosh Model | System Battery | Backup Battery |
| iBook G4 (Mid 2005) | 661-3686 | n/a |
| iBook G4 (14-inch Mid 2005) | 661-3699 | |
| iBook G4 (Late 2004) | 661-2994 | |
| iBook G4 (14-inch Late 2004) | 661-3189 | |
| iBook G4 (Early 2004) | 661-2994 | |
| iBook G4 (14-inch Early 2004) | 661-3189 | |
| iBook G4 | 661-2994 | |
| iBook G4 (14-inch) | 661-2998 | |
| iBook (Opaque 16 VRAM) | 661-1764 | |
| iBook (32 VRAM) | 661-2672 | |
| iBook (14.1 LCD 32 VRAM) | 661-2611 | |
| iBook (16 VRAM) | 661-2672 | |
| iBook (14.1 LCD 16 VRAM) | 661-2611 | |
| iBook (14.1 LCD) | 661-2611 | |
| iBook (Late 2001) | 661-2569 | |
| iBook (Dual USB) | 661-2569 | |
| iBook (FireWire) | 661-2391 | |
| iBook | 661-2391 |
PowerBook
| Macintosh Model | System Battery | Backup Battery |
| PowerBook G4 (17-inch 1.5GHz) | 661-2948 | 922-6395 |
| PowerBook G4 (17-inch 1.33GHz) | 661-2948 | 922-6064 |
| PowerBook G4 (17-inch) | 661-2822 | 922-5767 |
| PowerBook G4 (15-inch 1.5/1.33GHz) | 661-2927 | 922-6007 |
| PowerBook G4 (15-inch FW800) | 661-2927 | 922-6007 |
| PowerBook G4 (12-inch 1.5GHz) | 661-3233 | n/a |
| PowerBook G4 (12-inch 1.33GHz) | 661-3233 | n/a |
| PowerBook G4 (12-inch DVI) | 661-3233 | n/a |
| PowerBook G4 (12-inch) | 661-3233 | n/a |
| PowerBook G4 (1 GHz/867 MHz) | 661-2740 | 922-5205 |
| PowerBook G4 (DVI) | 661-2561 | 922-5205 |
| PowerBook G4 (Gigabit Ethernet) | 661-2561 | 922-4631 |
| PowerBook G4 | 661-2441 | 922-4361 |
| PowerBook (FireWire) | 661-2295 | 922-3829 |
| PowerBook G3 Series (Bronze keyboard) | 661-2183 | 922-3829 |
| PowerBook G3 Series | 661-2069 | 922-3380 |
| PowerBook G3 | 076-0719 | 922-2692 |
Desktop Computer Battery Info
| Battery part number | Type | Voltage |
| 922-4542 | Lithium | 3.6-3.9 V |
| 922-1262 | Lithium | 3.6 V |
| 922-4028 | Lithium | 3.6 V 850 mAh |
| 922-4760 | Lithium | 3.6 V |
Notes:
- The parenthetical product descriptions (Summer 2000) and (Summer 2001) refer to the summer of the Northern Hemisphere.
- The iMac (Flat Panel) computer's battery should only be replaced by an Apple Authorized Service Provider.