I have a Milestone running Android 2.1 Initially, battery life was terrible, so bad I was considering returning the phone: with only K-9 email imap idle push email on in the background, and auto-sync off, I could get barely 7-8 hours of battery life, whereas with the Nokia e71 and Iphone 3gs I would get at least a day and a half, with comparable usage (push email, ca. 20 emails a day, 30 minutes of web browsing and 20 minutes of calls a day). I then disabled background data, leaving the k-9 push email on, and now I get 2 days of battery life! This is great, of course, but it also raises another question: what on Earth was going on in the background that was draining the battery? Thoughts? Specifically, if you're interested in replicating my settings: I used 'any cut' to create a shortcut on the home screen to: settings -> account & sync. Once I untick 'background data', I can still use k-9 email, the browser, maps, etc, i.e. data-on-demand, if you will. If I want to access the market, I enable backgr data again. If I want to sync contacts and calendar, I enable 'account sync' from the power control widget (which enables background data, too), and then, once done, I disable background data and account sync. In k-9: menu -> folder list -> account -> settings -> background sync -> always. This way imap idle push works even when background data is off. I then have a remember the milk widget (but Astrid is a valid free alternative) with manual sync, and a pure calendar widget with, again, auto sync off. This is the best battery life I have ever had from a smartphone! But I am also curious to understand what was using data in the background and draining the battery so much... Having account sync off is a deal breaker for some, but for me it's ok: I don't update calendar and contacts every second, so the trouble of pressing a couple of buttons every now and then is well worth the extended battery life.