By Todd Bernhard
Las Vegas during the Consumer Electronics Show is the ultimate proving ground for a cellphone. First, consider that 100,000+ visitors are vying for already limited network connectivity. Constantly searching for a signal draws extra power. You are constantly on the go, away from your car or hotel making charging difficult. And you have to try to stay in touch with both your home and the office. These demands can push the iPhone's internal battery to the limit.