There has been a considerable amount of discussion about setting Push for
email in the 2.0 operating system for iPhone and iPod Touch, and whether
that affects battery life.

Here are the facts for IMAP connections.

It is possible that setting Push for IMAP connections will consume the
battery faster than not setting Push.  Apple has the technical information
as to why it happens.  Whether they do anything about it, or just document
it (they can argue that it isn't their problem), remains to be seen.

Since Apple has not documented it yet, I will document it for them:

Under ALL circumstances:
 [1] The BEST battery life setting is to have Push turned off, and Fetch
     set to Manually.

 [2] The SECOND BEST battery life setting is to have Push turned off, and
     Fetch set to Hourly.

 [3] The THIRD BEST battery life setting is to have Push turned off, and
     Fetch set to Every 30 Minutes.

The subsequent battery life ranking depend upon which of the following
three situations applies to you.  You need to test for yourself.  Your
situation may differ from your friends' situation.

Situation A:
 [4a] The WORST battery life setting is to have Fetch set to Every 15
      Minutes.  The setting of Push is irrelevant.

Situation B:
 [4b] The FOURTH best battery life setting, very close to the THIRD best
      battery life setting, is to have Push turned on, and Fetch set to
      Manually, Hourly, or Every 30 Minutes (I recommend Manually).

 [5b] The FIFTH best battery life setting is to have Push turned off, and
      Fetch set to Every 15 Minutes.

 [5c] The WORST battery life setting is to have Push turned on, and
      Fetch set to Every 15 Minutes.  You will not get mail any faster
      than you would using [4b].

Situation C:
 [4c] The FOURTH best battery life setting is to have Push turned off,
      and Fetch set to Every 15 Minutes.

 [5c] The FIFTH best battery life setting (MUCH WORSE than [4c]) is to
      have Push turned on, and Fetch set to Manually, Hourly, or Every
      30 Minutes.

 [6c] The WORST battery life setting (little different from [5c]) is to
      have Push turned on, and Fetch set to Every 15 Minutes.

My recommendation is that you use the best battery life setting (setting
[1]: Push off, and Fetch set Manually).  If you need automatic
notification, choose setting [2] or [3].

If you MUST have more frequent notification, test to make sure that you
are not in Situation C.  Push is a DISASTER with Situation C!!  Push is
ONLY beneficial in Situation B.

Regardless of what situation you are in, battery life will be the same
with Push turned off and Fetch set to Every 15 minutes.  This is the
safest setting if you want frequent notification.  If you are in Situation
B, turning Push on will give you better battery life and much faster
notification.  The downside is the disaster in Situation C.

-- Mark --

http://panda.com/mrc
Democracy is two wolves and a sheep deciding what to eat for lunch.
Liberty is a well-armed sheep contesting the vote.