How does using GMail via IMAP or Exchange affect battery life?
I have an IMAP and an Exchange email account on my iPhone 4S and when I only use Exchange my battery drains faster than when only using IMAP.
While I have configured IMAP to check for new email every 30 min, I must say I get lots of email in my Exchange account, that probably worsens the drainage.
Apple recommends here to &quot;Turn off push mail&quot;, so it is a known fact.
How much is battery affected? I can't give you a number, it depens on many factors (how often data is fetched, number of emails you get, size of the emails you get) so just test it: disable Gmail IMAP, configure Gmail ActiveSync and compare.
--EDIT--
After reading Michiel's answer below I was curious and googled &quot;push vs. fetch iphone&quot; and have seen quite a few debates. The outcome tended to be that using push conserves battery life, but some opinions just said &quot;it depends&quot;.
My configuration is probably unbalanced and that's why Exchange uses more battery than IMAP (which is fetched every 30 min and not the 15 min as I posted in my original answer, now corrected). Please take this answer as my personal (non representative) experience.
In the link above Apple also recommends to &quot;Fetch new data less frequently&quot;.
So again, test it and find out for yourself.
--/EDIT--