iPhone battery life vs. Push

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.

Mark Crispin <mrc@Panda.COM> wrote in
news:alpine.OSX.1.10.0807220904120.10623@pangtzu.p anda.com:

> The WORST battery life setting is

If you gotta instant message, wouldn't SMS be better than email? Email
sucks as an instant messenger.

Doesn't Gizmo have an Iphone app?

In message <alpine.OSX.1.10.0807220904120.10623@pangtzu.panda .com> Mark
Crispin <mrc@Panda.COM> wrote:

>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.

Are you using Gmail, or some other server with iPhone specific support
built-in?

The iPhone "mail" app doesn't appear to support the IMAP IDLE
instruction, which is what allows nearly any server and client to
effectively push mail out to any device capable of maintaining a TCP
connection. As a result, the "push" setting is more or less irrelevant
when using IMAP.

>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.

This makes sense, unless you have a user who manually checks mail
frequently. A user checking mail manually every 15 minutes will use
more power then the system doing it automatically since the user needs
to turn the screen on.

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

How much mail was being pushed during the test?

On most devices (and note, I haven't investigated the iPhone's battery
life yet), if each mail check event brings in exactly one message, push
vs fetch should consume roughly the same battery life. The more mail
coming in, the faster push will deplete the battery, but it consumes
only slightly more then waiting for a fetch.

However, if on average you receive less mail then your fetch setting,
you're better off with push. Consider a 9-5 office and a user who only
receives internal mail, checking every 'x' minutes from 5pm through 9am
will generally bring in no mail at all, whereas push only requires an
occasional heartbeat.