What we find most interesting about these results is how well they break down by manufacturer. The Asus laptops are off by exactly 10%. The HP laptops are off by 16 percent and 15 percent. The Sony laptops are off by exactly 15 percent. Only Toshiba and Lenovo show significant variance, but both are consistent in the direction of their results -- the Toshiba laptops underperformed and the Lenovo laptops beat their estimates.
Lenovo's IdeaPad U400 is the real surprise thanks to an insanely low manufacturer claim of four hours. We applaud Lenovo for apparently being more realistic about real-world results, but at the same time, Lenovo's laptops offered shorter run times than the competition.
Interpreting the results
The overall variance is negative 11 percent, but if we exclude Lenovo, the difference increases to negative 14 percent.
Does this mean that you should expect at least 14 percent less than what is claimed? Yes, it does. Though these 10 laptops are obviously only a small portion of the market, in our experience it is rare for any laptop to meet its claimed maximum life under any conditions that involve active use of the laptop.
Even expecting 14 percent less than what is claimed may be hopeful. The benchmark reference in this article is the least demanding of the two we use. Placing a heavy load on the processor is going to eat through the battery even more quickly. Playing a game, for example, can cut battery life below 50 percent of what is claimed.
Manufacturers account for this by using the words "up to" in their advertising. With that said, some manufactures walk a finer line than others. ASUS claims the UX31 can achieve 7 hours or more on the specifications page of its website. Toshiba claims that Z835 offers up to eight hours of "non-stop browsing, emailing, doing and enjoying." These claims are simply incorrect.
Though it's possible that a laptop will meet or exceed its claim, you shouldn't expect it. Instead, you should expect a laptop to come in below its maximum by at least 14 percent and -- more realistically -- around 25 percent.
A silver lining
All of this sounds a bit doom-and-gloom, so let's end on a high note. While we do find that laptops fail to meet their quoted endurance in our battery life benchmarks, there has been an upward trend in real-world battery life.
Five years ago you'd be lucky to achieve three hours with a basic desktop replacement, but the worst battery life we recorded among the systems in this comparison was a tad over five hours. The average buy should find this to be more than adequate. Even if claims are not being met, real-world battery results do not fail to impress.
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