In the interest of consolidation, I thought it might be a good idea to list the best hints and tips aimed at getting the most battery life out of the phone. Specifically, customising settings and installing programs. I will probably need help with making this comprehensive, so if I've missed something, let me know.
Settings:
Signal Recievers:
Probably the single best way to increase battery life is to turn off receivers that you are not currently using. The phone includes home screen widgets that can be used to quickly toggle them on/off. More on which ones and how later. The antennas that can be turned off are as follows:
Aeroplane Mode
This is a setting that will simply turn off all antennas in one stroke. Most importantly, this includes turning off calling/texting ability, so you should only use this setting when you don't want anyone to be able to contact you through the phone in any way.
Menu button>settings>wireless & networks
Bluetooth
This is a setting that will turn off the ability to wirelessly connect to accessories. Things like hands free kits, wireless headphones, dedicated GPS devices, etc.
Menu button>settings>wireless & networks
GPS
This is the receiver that picks up signal from a satellite network. By measuring the time it takes the phone to send and receive a ping signal (like 2 computers saying "hello" to each other) to several satellites at once, it can calculate how far away it is from those satellites. This allows the phone to triangulate it's location. This is obviously useful for things like showing you where you are on a map, or telling you what the current local weather predictions are.
Menu button>settings>location
Mobile Data
This allows the phone to use the mobile network to get access to the internet at broadband speeds. Of course you need to be within range of a mobile tower capable of transmitting this data. aside from using up battery life, this data can be quite expensive, so there is more than one reason to turn it off when you are not using it.
Menu button>settings>wireless & networks>mobile networks
Wi-Fi
This receiver allows the phone to wirelessly connect to local computer networks. On a device such as the Desire, the primary reason to connect to these networks is to gain internet access through a cheaper and perhaps more reliable medium than the mobile data system.
Menu button>settings>wireless & networks
Screen Backlight:
This setting allows you to adjust how bright the screen is. The phone has a built in detector and automatic setting to adjust the brightness according to the environment. Personally, I find that the auto mode does not work well enough and I manually adjust my brightness with a widget app. More later
Menu button>settings>sound & display
Auto Sync
Automatic Syncing of data for various apps on the phone. Things like email, face book, weather, calendars, etc. The frequency of the updates can be adjusted and the less often they update, the more battery power you save. This setting has a widget, more later.
Menu button>settings>accounts & sync
Also, the various syncing apps usually have settings that you access by pressing the menu button from within the app.
Widgets:
(I'm going to assume you still have Sense UI for this section. If you do not have Sense UI, you should be able to translate it to whatever rom you flashed your phone too.)
There are several widgets that you can use to either keep you informed about your phone's status or allow you to quickly change settings. Most of the widgets you need are already included with the Sense UI, but there are some that you can download from the market.
The Widgets that I suggest you add are:
GPS
Bluetooth
Wi-Fi
Mobile Data
Brightness Level*
Manual Sync**
Battery time lite***
*Market download by Motalen
**Only really useful if you have set your sync settings to manual or infrequent
***Market download by Curvefish
To add widgets to your phone, from the home screen:
+>widget>Power control
This is an all in one widget that includes:
Wi-Fi
Bluetooth
GPS
Manual Sync
Brightness
+>widget>Settings>~
These are individual widgets for:
Airplane mode
Bluetooth
GPS
Mobile Data
Wi-Fi
Market Download Apps & widgets:
Battery Time lite:
by Curvefish
this app has a widget that has a percentage number for battery remaining.
It also adds a percentage to the status bar.
When loaded, the app will tell you how long you can perform various functions, like make calls or use the internet. Unfortunately, those figures are only a guide because the times are preset & can not be adjusted for if your battery performs a little better or worse than the average. (If anyone knows of an app that records battery histories and automatically adjusts the times, I'd love to know about it).
Spare Parts:
By Android Apps
This app allows you to tweak a few things to increase battery life, like turning off some animations which consume more power. It also logs a lot usage history that can be useful.
It's best function is that it can list apps that put the phone into 'partial wake mode' which can drain a lot of battery.
Launch app>battery history>first drop down menu> partial wake useage
If it lists any apps that have very high usage, you might want to consider removing that app. Note that if you, for example, listen to a lot of music, then the usage for the music app will show very high. Not much you can do about this other than stop listening to music.
*note* there is a bug that some people experience where Calendar is listed with a very high partial wake, for a possible solution to this problem, try this thread:
-link-
Brightness Level:
by Motalen
This useful little app allows you to quickly adjust the brightness of the display if you have the auto brightness turned off.
Task Killer Apps:
There is an ongoing debate about whether this sort of program is needed. Android does a very good job at managing running apps to conserve battery life, but there may some advantage to it with certain apps. It should also be pointed out that the task killer app uses battery power to track which apps are running. It might be best to tell the task killer to kill itself & only launch it when you want to stop apps.