Reckless usage of any 3G device, including T-Mobile's G1, can kill a fully charged battery in a matter of hours. With the benefit of history and some key Android apps, G1 owners can take precautions to extend their battery lives.

In June, PC World ranked the relative battery life of a dozen 3G smartphones. All of them tested in the "fair" range, except for the Palm Treo 750 which ranked as "poor." The issue of interest at the time was the battery life of the iPhone 3G, which has been called everything from "Questionably Adequate" to "Garbage."

But 3G battery consumption was a known issue even before the first generation iPhone was released. Steve Jobs made it known that a 3G radio was left out of the first iPhone in the interest of maintaining the battery life of the device. When the iPhone 3G was released, it had to compete with the reputation of its EDGE predecessor, which PC World tests found to have 10 hours of battery life, no doubt the source of disappointment in many users.

It's a long preface to a simple, but extremely important first step: Turn off 3G. From the G1's home screen, press Menu > Settings > Wireless Controls > Mobile Networks and then turn off data roaming and click on Use only 2G Networks. Go back one screen and make sure Wi-Fi and Bluetooth are also off (they should be by default). GPS is also left off by default, this should stay off.

You're going to want to turn 3G on and off without going through five menus, so use the Any Cut app -- this is one of the most useful applications available in the Android Market, and it's free, so there is no excuse to not have it -- to create a home screen shortcut. Select New shortcut, then press Activity > Wireless Controls, name the shortcut, and click OK.

While in Any Cut, it would behoove you to also create a home screen battery monitor by pressing Activity > Battery info. This little shortcut will offer you detailed information about the battery's status, such as: level, scale, health, voltage, temperature, awake time on battery or when charging, as well as screen on time and time since boot.

The next thing G1 users can learn from iPhone battery conservationists is to set data sync to a reasonable level. Under Menu > Settings > Data Synchronization, turn Auto-sync off. The others -- Gmail, Calendar, and Contacts -- can be left checked and synced as necessary.

Menu > Settings > Sound&Display > Brightness will allow you to turn down the screen brightness. By default, it should be somewhere around 25%, and it can actually be reduced quite a bit and retain acceptable luminescence. By pressing Back and going to "Screen Timeout", the default one-minute screen light time can be halved to 30 seconds. Turning off the keyboard's backlight is not yet possible.

With all the defaults left in place, you will be lucky to get three hours of continuous use out of the G1. Fortunately, Android's customization options make it very easy to alter system settings.