That's why there are a growing number of manufacturers who have extended battery packs for the iPhone on the market. For example, I looked at the Kensington Mini Battery Pack and Charger (US$49.99), but the website doesn't show that it works with the iPhone 3G.
My next choice was the Richard | Solo Smart Backup Battery. This US$49.95 lithium-ion battery pack has saved me from running out of juice prematurely more than once!
Read on for more information about this must-have sidekick for the iPhone 3G. In case you're wondering about the company name, Richard | Solo is the new retail startup of Richard Thalheimer, the man behind Sharper Image. That's why you'll also find the Smart Backup Battery wedged into the website between the 3 in 1 Travel Groomer and a radio-control Ferrari. Don't let that bother you, though -- the Smart Backup Battery works very well. It's also certified by Apple as "Made for iPod" and "Works with iPhone", so you know it's going to work well with either type of device.
This is a small add-on, although most of the current battery extenders for iPhone add a lot of length to the iPhone's dimensions. The dimensions are 1.77" wide x 2.83" high x .49" thick (4.5 x 7.2 x 1.25 cm), and the 1200mAh battery weighs only 1.76 ounces (50 grams). The Smart Backup Battery comes with a retractable cable USB AC adapter (above) that has a mini-USB connector on one end that fits into the socket on the battery. What's nice is that you can unplug the AC adapter, plug the USB cable into an available port on your Mac or PC, and then charge the Smart Backup Battery and your iPhone simultaneously.
Another cool feature is that the case of the battery is made out of aluminum rather than plastic, so worries about scratching or cracking the case are eliminated. I often put the included plastic cap over the iPhone connector and drop the Smart Backup Battery into the back pocket of my pants, and the aluminum case withstands the pressures of sitting very well. Wondering about the warranty? There's a 30-day satisfaction guarantee upon purchase, and a materials and workmanship warranty for 90 days. My one complaint is that the warranty should be longer, as the Kensington product offers a one-year warranty for the same price.
The Smart Backup Battery takes about 3.5 hours to charge, although Richard | Solo recommends that you charge the pack overnight for the first two nights to "top it off." The battery's capacity is about 70 - 80% of the iPhone's battery capacity, so if you are still in the green on your iPhone battery, plugging in the backup battery will bring your iPhone up to a nearly full charge. Richard | Solo warns that if your phone is already below a 20% charge, you won't get a complete recharge. If you top off your iPhone with the backup battery while the iPhone still has a good charge, the backup battery automatically shuts off when the iPhone is at 100% charge and retains the rest of the charge for later use.
There are three LEDs on the face of the Smart Backup Battery. The first is a blue light that turns on when the Smart Backup Battery reaches a 100% charged state, the second is a blue light that shows when the backup battery is charging the iPhone or iPod. Finally, there's a third LED that changes color depending on what's going on. If you're charging the Smart Backup Battery, the LED is solid red. If you have the iPhone or iPod connected and charging at the same time, the LED doesn't light up until the device is fully charged and the Smart Backup Battery begins to charge up. If the Smart Backup Battery is just about completely discharged and needs to be recharged, the LED flashes red. Finally, if it's hooked into an iPhone or iPod and the LED turns green, the device is fully charged.
According to Richard | Solo, the Smart Backup Battery is good for about 300 charge / discharge cycles. They do not recommend frequent complete discharges, although they suggest that you do it about once every 30 charges to calibrate the battery.
Real Life Situation
Here's a standard situation that I run into frequently. I charge up my iPhone 3G and the Smart Backup Battery every night. I make calls during the day, check stock prices and weather info, and send a few texts and Tweets. Later in the day, I find myself playing games on the iPhone, so after about 2.5 hours of that my battery decides to go into the red zone. I plug in the Smart Backup Battery, and just let it charge the phone up while I'm using it -- this is not the optimum way to use the battery, but it does let me continue working with the iPhone for about another 2 - 2.5 hours.
I found the Smart Backup Battery to be indispensable with my iPhone 3G and unlike my American Express card, I don't leave home without it. If any TUAW readers have tried this or other iPhone battery extenders / chargers, please leave a comment and tell us your experiences.