Exchange mail account kills iPhone battery. Why?

"It is not so much Exchange but more just having the 3G connection on 24x7.

You can try (only speaking from personal use of version 2) going to settings, then one of the top options is ""fetch new data"" (or along those lines) and try to turn it down slightly so it checks in a lot less frequently.

That being said, I can not say if the 3g connection won't drain the battery if it is just on but not fetching data. - You may want to see if there is any way to disable it / set it to on-demand.

Edit - for reference, I had a Sony Ericsson phone with 3G, the battery lasted around 3-4 days, however if I kept MSN messenger working in the backgruond with 3G on, I was lucky to get ~12 hours."

"It doesn't have to be Exchange or a 3G. I have one of the original iPhones, and having it periodically check my mail was killing my battery life. I couldn't get through a whole day.

Currently, it checks when I tell it to, not on its own, and I have no problems with battery life (unless I play Civilization Revolution)."