How can I improve the battery life on my device? Possible Duplicate:
  What can I do to increase battery life on my Android device?  




My Desire is absolutely great, but with my usage the battery life is really a big problem.

I have a few apps running and polling in the background, obviously the Google stuff (Gmail, Talk, Maps probably poll because of Latitude). Then I have Twitter running (checks every 5 minutes), Google Listen (checks every hour). Google Market also checks for updates sometimes apparently, don't think I can switch that off.

My usage is pretty heavy, on my bicycle I listen to Spotify or a podcast for 20 minutes, then in the morning train (45 minutes) I will usually read Twitter and Google reader (the web app). Then I get to work and my battery is down to about 75%-70%. I usually charge it but if I don't then I will be out of battery by about 6PM. So thats 9 hours of battery life. The commute back is pretty much the same, battery will be dead before I get home.

I don't want to give up on instant notifications, so the 3G will always be on.

When I went camping for a weekend I turned all of the above polling off and only checked Twitter about 4 times, didn't use the phone for the rest of the day. Battery life improved slightly to about 14 hours. Still not great, I was hoping for at least 24 hours.

WiFi is always off by the way!

I've tried rebooting but the timings are mostly the same. Is it wise to buy a battery that can provide more mAh? Is there any good solutions for backup power when I don't have power available, when camping for example (aside from buying extra batteries)?
Go to StartScreen/Menu Key/Settings/About Phone/Battery/Battery use. It tells you which of your applications are using how much energy. Then you can make a more informed decision about whether certain applications are worth their energy usage.