Question: Does using iMessage eat up more battery than normal text messaging?
Answer: Yes — and so does using Google Voice, Facebook or any other Internet-linked app for on-the-go messaging instead of a phone's standard texting function.
It's not going to be a huge difference. These apps need little bandwidth to send or receive short messages; your phone's browser, map, and social-media applications are much more likely to run down its battery.
It's often worth making that tradeoff. Using texting alternatives like Apple's iMessage, Google Voice texting, Facebook Messages and Twitter direct messages won't count against whatever quota your current plan might impose on texts. These applications let you read and answer notes from friends on a wider choice of devices, even computers with real keyboards (although iMessage won't permit that last option until Apple's OS X Mountain Lion ships). Many of them let you see if the other person is online to read your message.
Plus, these systems automatically back up your messages instead of letting them evaporate when you upgrade your phone's software or replace the phone itself.
But texting is the most efficient communications option available on our phone. A single text takes up a scant 140 bytes. And because texts go out over spare bandwidth on a background communications channel that your phone already has to keep active to stay on your carrier's network, they subtract next to nothing from battery life.
(The prices most carriers charge for text messaging doesn't reflect those costs, but that's a subject for another column.)
So if you're running low on battery but need to stay in touch, turning off mobile data entirely and relying on text messaging can prolong your phone's usable life.
To do that on an iPhone, open the Settings app, select "General," then "Network," then disable cellular data. In Android, open Settings, then select the "Wireless & Network" category, choose "Mobile networks" and uncheck "Data enabled." Note that the exact interface will vary depending on what sort of extra software layer a manufacturer or carrier slapped down over Google's operating system.
Text messages also have the advantage of working over unreliable bandwidth (a lesson many mid-Atlantic residents learned after the derecho storm of late June). Even when your phone can't sustain a voice call or get anywhere online, texts should continue to worm their way through the airwaves.
That's why Apple's iMessage defaults to sending a message via standard SMS if no data connection is available.
Tip: Get your app inventory down to size
The eight or 16 gigabytes of storage on many smartphones can start to feel cramped, especially if you develop a taste for trying new apps or copy over some large video files first. But once you start to get warnings about running low on storage space, it may no longer be obvious which apps ate up the most capacity.
To check that on an iOS device, open the Settings app, then tap General and then Usage. On my wife's iPhone 4, the single biggest tenant (after 1.5 gigabytes of music) was Apple's GarageBand, weighing in at 1.1 GB; iPhoto followed at 151 megabytes, then Facebook at 57.7 MB and Bejeweled at 56.4 MB.
On an Android device running the current (but still depressingly rare) Ice Cream Sandwich version, open the Settings app and then select its Apps, Applications or Application Manager category; on older phones, open Settings, choose Applications, then Manage Applications. In either situation, you'd then touch the menu button and select "Sort by size." On one new Android phone, Google's Chrome led the list at 99 MB, followed by Google+ (33 MB), Netflix (27 MB) and Gmail (26 MB).
Most Android phones will also allow you to move individual apps from the phone's primary storage to an SD Card; you'll usually see that option if you select an individual app from that list.