I’ve been asked for suggestions on how to do this a ton of times; here are several tweaks I use for my HTC Desire that easily extend its battery life to get me through the day. And with charge to spare. Do these (in no specific order):
- Disable 'Background Data' from Settings | Accounts and Sync. This notorious setting sucks battery life big time by keeping tons of Google apps (Gmail, Contacts, Calendar etc) continuously in sync. Better to just let these apps update only when you need them.
- Install Advanced Task Killer--a super little app that lets you 'kill' unnecessarily running apps as often as you need. I invoke this several times a day; especially after extended bouts of using multiple apps. This one's a must-have.
- Disable any radios when you don't need them (WiFi, Bluetooth, GPS). I've installed nifty shortcut widgets to these radio settings on my home screen--beats having to poke into the Settings screen each time.
- Beware of installing unverified apps--some of these run continuously and suck battery life.
Bonus tip: If you know you’re going to be in a location with no cellular service, switch your phone to airplane mode. This disables all radios (including cellular,) and prevents your phone from ‘searching’ for a signal and draining its battery in the process.
Not just for the HTC Desire—these tweaks should work with virtually any Android device. Made a huge difference for me, but your mileage may vary.