A couple of days ago, Qualcomm dedicated an entire blog post detailing the design of its upcoming Snapdragon 820 system-on-chip (SoC), with special focus on Kryo, its first custom-designed 64-bit quad-core CPU. The company claimed that the chipset will be up to twice as powerful and energy efficient as its predecessor, Snapdragon 810. Being related to SD820, the post, obviously, received widespread coverage. However, many popular online publications interpreted Qualcomm's claim on SD820's power efficiency as saying that it will double your device's battery life - see reports from Economic Times, The Next Web, and WMPoweruser. Independent analyst and consultant Richi Jennings was the first to point this out, claiming that the interpretation isn't correct. "OK, so obviously there's a world of difference between an SoC that's up to 2x as efficient and an entire phone getting double the battery life," he said in an article on ComputerWorld. "For starters, the 820 isn't going to make today's huge displays suck any less power, amirite?" He also pointed to a Forbes article that explains how the 820 is so much more efficient - you can read that article...
Source: http://www.gsmarena.com/report_qualcomms_claim_on_sd820s_power_efficiency_doesnt_mean_double_the_battery_life-news-13849.php