I've been looking into squeezing as much as possible out of battery life. The X10 has a big screen that seems to take a lot of battery power. I've done the usual settings adjustments such as dimming the screen, reducing the screen timeout, and decreasing the frequency of network updates (e.g. Facebook/Twitter).
However, I found a couple of apps that seem to be useful to get even more out of the battery:
- Advanced Task Killer
- JuiceDefender
The first one is a simple app that lists what apps are running. You check the ones you want to "kill" and press the kill button and it shuts them down. I'm still learning how Android works, but it's my understanding that the OS automatically multitasks apps when you launch them. That is to say, if you launch an app, it will in most cases reside in memory until you actively close them somehow. Advanced Task Killer is a quick and easy way to drop things out of memory to keep things fast and to save your battery power.
JuiceDefender is a bit more obscure to me. It resides in memory and actively conserves power based on usage. For example, if you aren't using your phone, it will preserve power. One way it does this is downgrading your network connection to 2G when not in use. It does other things too such as reducing CPU load while the phone is idle. The full version (under $5) gives you more control over wi-fi and data connectivity when idle. Even with the free version, I have noticed an increase in battery life. However, this is likely in conjunction with Advanced Task Killer. It's been getting good reviews, which is how I found it.