Apple: Consumer Reports used a battery test that 'does not reflect real-world usage'

Right before Christmas, Consumer Reports, one of the most famous product review publications, announced that it could not recommend Apple's latest MacBook Pro because of inconsistent battery life.

But shortly after the review was published, questions about Consumer Reports' testing surfaced, such as how it claimed to get both 3.75 hours of battery life and 19.5 hours from the same laptop - which is obviously a huge disparity.

Turns out, it was a software issue, Consumer Reports said in a blog post on Tuesday. Consumer Reports now says the MacBook Pro is poised to receive a recommended rating again if battery life remains consistently high.

"We communicated our original test results to Apple prior to publication on Dec. 22 and afterward sent multiple rounds of diagnostic data, at the company's request, to help its engineers understand the battery issues we saw in our testing," Consumer Reports wrote in a blog post.

"After investigating the issue, Apple says that the variable battery performance we experienced is a result of a software bug in its Safari web browser that was triggered by our test conditions."

Apple said that the issue was related to a setting that Consumer Reports uses on its testing. "We learned that when testing battery life on Mac notebooks, Consumer Reports uses a hidden Safari setting for developing web sites which turns off the browser cache. This is not a setting used by customers and does not reflect real-world usage," an Apple spokesperson told Business Insider.

You can read Consumer Reports' latest blog post here.

to Business Insider:

"We appreciate the opportunity to work with Consumer Reports over the holidays to understand their battery test results. We learned that when testing battery life on Mac notebooks, Consumer Reports uses a hidden Safari setting for developing web sites which turns off the browser cache. This is not a setting used by customers and does not reflect real-world usage. Their use of this developer setting also triggered an obscure and intermittent bug reloading icons which created inconsistent results in their lab. After we asked Consumer Reports to run the same test using normal user settings, they told us their MacBook Pro systems consistently delivered the expected battery life. We have also fixed the bug uncovered in this test. This is the best pro notebook we've ever made, we respect Consumer Reports and we're glad they decided to revisit their findings on the MacBook Pro."

Visit Markets Insider for constantly updated market quotes for individual stocks, ETFs, indices, commodities and currencies traded around the world. Go Now!