Here’s a couple of tricks you can use to eek a bit more life out of your old battery between recharges.
1. Turn off the keyboard backlights by pressing F5.
2. Turn off Bluetooth in the menu bar.
3. If you’re not using the Internet, turn off Wifi in the menu bar.
4. If you are using the internet, but you’re not expecting or bothered about receiving mail for a time, quit Mail or any other email client app. If you still want to check your email and you use a web-based mail service like GMail, you’ll use less battery power if you quit Mail, and open GMail directly in your browser window.
5. Reduce the hard disk drive sleep time (formerly known as ‘spindown’). By default, your Mac will power down the hard disk after 10 minutes inactivity on battery power. You could try setting that to 5 minutes (any less, and you’ll probably lose what you gain as the the HD will end up having to power up more often than necessary).
To do so, open Terminal, and copy/paste this command:
sudo pmset -b disksleep 5
After pressing ‘Return’ on your keyboard, you will need to enter your password, which will be invisible when you type it (so type carefully).
If you want to change it back to its default anytime in the future, just use the same command but change the ‘5’ to ’10’.
This doesn’t affect the spindown time when you’re on mains power.