More on iPhone G3, GPS and power management

One of the big concerns about the iPhone G3 before the announcement was how it might handle the power drain from the global positioning chip and the software that might use it. But Apple is taking a less is more battery life approach.

In an article on TidBITS, Glenn Fleishman talked to Greg Jozwiak, Apple vice-president of marketing for iPod and iPhone about the issue.

I also extracted some detail about how the GPS will work in relation to both battery life and permission. A GPS can be a dangerous thing: What if you don't want your location to be known? It can also be a battery drain.

Jozwiak said that the GPS function is only active when you're using it; this is part of the whole philosophy of no unnecessary background activities to preserve battery life and functionality.

When you use the Maps application, you'll be able to choose whether or not to use the GPS location and tracking features. Likewise, if a program wants to use the Core Location feature available to developers, the iPhone (any model) will ask your permission to allow this use. Core Location uses GPS, WiFi, and cell-tower location.

This sounds similar to a developer message about how notifications and background tasks would be handled. It was delivered by Scott Forstall, senior VP of iPhone software, during the keynote.

He said that Apple would offer developers a single pipeline for pushed notifications to their programs. Instead of running background tasks, which could hit battery life, performance and reliability, developers will use this notification service.

The service can push three types of notifications: badges, sounds and text alerts.

For easy reading, I took Apple's power performance claims for the iPhone 3G and matched them with their fine print from the company's technical specs page. As always, actual results may vary:

Talk time: Up to 5 hours on 3G; Up to 10 hours on 2G.

Testing conducted by Apple in May and June 2008 using preproduction iPhone 3G units and software. iPhone 3G units were connected to a 1900MHz network or a 2100MHz network. All settings were default except: Call Forwarding was turned on; the Wi-Fi feature Ask to Join Networks was turned off. Wi-Fi was enabled but not associated with a network. Battery life depends on the cellular network, location, signal strength, feature configuration, usage, and many other factors. Battery tests are conducted using specific iPhone units; actual results may vary.

Standby time: Up to 300 hours.

Testing conducted by Apple in May and June 2008 using preproduction iPhone 3G units and software. All settings were default except: Call Forwarding was turned on; the Wi-Fi feature Ask to Join Networks was turned off. Wi-Fi was enabled but not associated with a network. Battery life depends on the cellular network, location, signal strength, feature configuration, usage, and many other factors. Battery tests are conducted using specific iPhone units; actual results may vary.

Internet use: Up to 5 hours on 3G; Up to 6 hours on Wi-Fi.

Internet use over 3G: Testing conducted by Apple in May and June 2008 using preproduction iPhone 3G units and software. Internet over 3G tests were conducted over a 1900MHz 3G network using dedicated web and mail servers, browsing snapshot versions of 20 popular web pages, and receiving mail once an hour. All settings were default except: Call Forwarding was turned on; the Wi-Fi feature Ask to Join Networks and Auto-Brightness were turned off. Wi-Fi was enabled but not associated with a network. Battery life depends on the cellular network, location, signal strength, 3G connectivity, feature configuration, usage, and many other factors. Battery tests are conducted using specific iPhone units; actual results may vary.

Internet use over Wi-Fi: Testing conducted by Apple in May and June 2008 using preproduction iPhone 3G units and software. Internet over Wi-Fi tests were conducted using a closed network and dedicated web and mail servers, browsing snapshot versions of 20 popular web pages, and receiving mail once an hour. All settings were default except: Call Forwarding was turned on; the Wi-Fi feature Ask to Join Networks and Auto-Brightness were turned off; WPA2 encryption was enabled. Battery life depends on the cellular network, location, signal strength, Wi-Fi connectivity, feature configuration, usage, and many other factors. Battery tests are conducted using specific iPhone units; actual results may vary.

Video playback: Up to 7 hours.

Testing conducted by Apple in May and June 2008 using preproduction iPhone 3G units and software. Video content consisted of a repeated 2-hour 23-minute movie purchased from the iTunes Store. All settings were default except: Call Forwarding was turned on; the Wi-Fi feature Ask to Join Networks and Auto-Brightness were turned off. Wi-Fi was enabled but not associated with a network. Battery life depends on the cellular network, location, signal strength, feature configuration, usage, and many other factors. Battery tests are conducted using specific iPhone units; actual results may vary.

Audio playback: Up to 24 hours.

Testing conducted by Apple in May and June 2008 using preproduction iPhone 3G units and software. The playlist consisted of 358 unique audio tracks, a combination of content imported from CDs using iTunes (128-Kbps AAC encoding) and content purchased from the iTunes Store (128-Kbps AAC encoding). All settings were default except: Call Forwarding was turned on; the Wi-Fi feature Ask to Join Networks was turned off. Wi-Fi was enabled but not associated with a network. Battery life depends on the cellular network, location, signal strength, feature configuration, usage, and many other factors. Battery tests are conducted using specific iPhone units; actual results may vary.