A new study conducted by Which? magazine has found that "the battery life claimed by laptop manufacturers rarely lives up to reality. "Although Apple's battery life claims were the closest to reality, in the case of some other manufacturers, their laptops lasted hours less than the stated time," reports Digital Trends. From the report: In its testing, Which looked at the battery life claims of 67 different laptop models from manufacturers as diverse as Asus, Apple, Acer, HP, Dell, Lenovo, and Toshiba -- some of the world's most popular laptop makers. It found that while Apple's average claim of 10 hours was proven correct -- and was even slightly better in some cases -- Dell's claims were overstated by more than four hours, and HP, close to five. The times listed in the header image are the average claimed battery life for all of the laptops Which? has tested over the past year versus the times it recorded in its internal testing. That involved charging the laptops to full, then running them down to nothing three times, using online web browsing via Wi-Fi or watching local videos to do so. Out of all laptops tested, the only manufacturer to understate battery claims was Apple. In one case, it claimed that its MacBook Pro 13 could achieve 10 hours of usage, while tests suggested it could go for as long as 12 hours. At the other end of the spectrum though, there were some really egregious overstatements. The Lenovo Yoga 510 has a claimed battery life of five hours -- it only lasted two hours and seven minutes. The HP Pavilion 14-al115na is supposed to be able to run for nine hours, but was only capable of four hours and 25 minutes. The Acer E15 claimed six hours but ran for just under three hours.