Fast Phones, Dead Batteries

4G smartphone users are discovering their speedy broadband service also zips through battery life. The main culprit is spotty 4G service—even in the nation's largest cities—which requires the phones to search constantly for a signal, draining their batteries.

Fourth-generation service is just starting to take hold, but complaints about battery life could slow the push by wireless carriers to convert customers to the higher-speed networks. Smartphone makers, however, are working on ways to respond to the new power demands. Verizon Wireless, AT&T Inc. and Sprint Nextel Corp. are investing billions of dollars to expand their 4G networks over the next two to three years on a technological standard known as long-term evolution, or LTE, with the promise of speeds of as much as 10 times those of the ubiquitous 3G service. The spottiness of 4G stems at least in part from the measured approach carriers have taken to it, rolling out the service city by city. There were just 6.3 million subscribers of 4G LTE in the U.S. at the end of last year out of a total of 138.4 million smartphone users, according to research firm Informa Telecoms & Media.