Lenovo is claiming that its new Yoga tablets will offer 18 hours of battery life when browsing the web, which would be the longest when compared to other tablets.The company's new Yoga tablets, which will come in 8-inch and 10.1-inch versions, will provide 12 to 14 hours when watching high-definition video, said Stephen Miller, Lenovo ambassador. The tablets were announced at a launch event in New York.