Consumer Reports Retesting MacBook Pro’s Battery Life, Apparently Due To Bug In Safari

After being the first MacBook Pro to not receive a recommendation from Consumer Reports, the company is now retesting the battery life on the machine with the latest macOS Sierra beta which addresses a potential issue with the computer’s battery life.

Working with Apple over the holidays, the two began working on figuring out the battery test results and have now begun retesting the battery starting this week.

Battery life issues are common on a new machine as it’s constantly doing much more work than usual. But over time that should begin stabilizing. However, Apple’s reaction to the issue was to remove the battery remaining indicator as it didn’t accurately represent the machine’s battery life with things such as iCloud in mind.

Once the test results were sent to Apple at their request, engineers began taking looking into the problem and diagnosing the issue. It ultimately boiled down to a software issue within Safari.

Apple’s statement to Consumer Reports:

“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.”

Consumer Reports turns off browser caching in their tests in order to load every page new, rather than relying on a cached web page on the computer.

In regards to disabling the browser cache, Apple’s response is:

“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.”

The Safari bug has now been fixed and is now available in the latest macOS 10.12.3 beta.