After being the first MacBook Pro to not receive a recommendation from Consumer Reports, the company is now stating that the latest macOS Sierra beta addresses a potential issue with the system’s battery life.

Working in conjunction with Apple over the holiday, the two have worked together to better understand the battery test results as promised and new testing is taking place this week…

The controversial battery findings posted just before the Christmas break from Consumer Reports received a response from Apple SVP Phil Schiller who said Apple would begin working with the publication to understand what caused their lab testing to report sporadic battery life.

Even though the publication’s test results seem far-fetched at the time, Consumer Reports stood by their findings and didn’t believe another test was warranted. Today’s development leads us to believe that Apple has potentially found a bug that may have negatively impacted CR‘s testing.

Battery life issues tend to be common as new devices are set up, which may be the reason a large number of 9to5Mac readers reported lower than expected battery life issues. Apple responded in part by removing the time remaining estimate from the battery status indicator which didn’t reflect accurately with modern software like iCloud.

Once test results and diagnostics had been sent to Apple at their request, the engineers began looking into understanding the battery issues that arose. Apple stated that the battery life concerns Consumer Reports unearthed arose from a software bug within Safari, something that was triggered by CR’s testing methodologies.

In a statement given to Consumer Reports, Apple said:

“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…. We have also fixed the bug uncovered in this test.”

As a part of CR’s laptop testing, they turn off caching within the browser. The goal is to have the system load each web page anew, rather than relying on a cached page saved on the computer. According to CR this “allows us to collect consistent results across the testing of many laptops, and it also puts batteries through a tougher workout.”

In regards to the caching issue, Apple’s statement said:

“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. [Consumer Reports’] 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…. 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.”

Consumer Reports is now re-running their tests this week to determine whether or not the expected fix will resolve their original issues which could potentially change their Do Not Recommend verdict. We’ll keep you posted as the situation develops.

The aforemtioned bug fix in Safari should be found in macOS Sierra 10.12.3’s latest beta.

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