Like a laptop, most of the power in a PDA is used by the backlight; for a Windows Mobile device, every minute you spend with the backlight on is ten minutes less standby time, so turn it down and set it to time out quickly. The CPU also uses a lot of power - an application using the CPU 1% of the time cuts your standby time to a tenth of what it would otherwise be.

Use http://www.vistabug.com/pxaclocker/ to set the CPU speed for Palms. Close applications rather than switching between them, because switching tasks uses a lot of CPU power. Be careful with applications that keep the system awake; if you're signed in to MSN Messenger with Pocket MSN, even pressing the power button doesn't suspend a Pocket PC.

IRDA doesn't use enough power to be worth turning off, but disable WiFi and Bluetooth when you don't need them. Turn off sound effects you don't want. If your PDA is also a smartphone, remember that loud rings and vibrate mode take more power; the vibration motor needs enough power to physically move the device, though it's only on for a few seconds.

GPRS, EDGE, 3G and Wi-Fi use more power for web browsing than a standard phone call. If you're in an area with a poor phone signal, your phone will use more battery staying in touch with the network. It's not usually worth checking or turning your phone on and off, but if there's a room in your house with particularly poor reception, don't leave your phone in there overnight.

MP3 Power

Remember to use the hold button on your MP3 player to stop the play button from being hit accidentally, leading to the player running when you don't notice. Set the backlight to turn off quickly. Turn off the EQ to save power; if you've added EQ to tracks in iTunes, use the Flat setting on an iPod to turn the EQ off. Turn off Sound Check volume levelling. Avoid uncompressed files; encode music at a lower bit rate or split long files like podcasts and audio books into small files - this way the files will fit into the cache, so your player doesn't need to access the disk or main memory as often.

Keep the volume down. Noise isolating headphones give you better sound and let you play your music more quietly - not only does that protect your ears, it also uses a little less power. If you use a case, make sure the player isn't getting hot when it charges, which will lead to decreased battery life.

Look for a player with an easily replaceable battery. You can get newer, higher capacity batteries for iPods from http://www.newertech.com/ and http://www.sonnettech.com/, but fitting them can be tricky.

Digital Camera Power

The LCD uses most of the power on a camera; use the optical viewfinder instead and you could squeeze five times as many shots out of your camera.

Don't use alkaline batteries in a camera that runs on AA cells, except in emergencies. They don't deliver enough power to last very long, and high power alkaline or lithium batteries are expensive. Invest in a set of rechargeable NiMH batteries; look for at least 1700 to 1850 mAh for good battery life. [good quality modern AA NiMHs are now over 2300 mAh.)