(Update: Consumer Reports tested the new MacBook Pros after Apple issued a fix in response to our initial battery test results. We now recommend the laptops.)

Apple launched a new series of MacBook Pro laptops this fall, and Consumer Reports' labs have just finished evaluating them. The laptops did very well in measures of display quality and performance, but in terms of battery life, we found that the models varied dramatically from one trial to another.

As a result, these laptops are the first MacBooks not to receive recommended ratings from Consumer Reports.

Complaints about MacBook Pro batteries have been popping up online since the laptops first went on sale in November. Apple says that these computers should operate for up to 10 hours between charges, but some consumers in Apple's support forums reported that they were only able to use their laptops for three to four hours before the battery ran down.

Apple declined to comment on our test results until they better understand the issue, but emailed this statement: "Any customer who has a question about their Mac or its operation should contact AppleCare."

What We Found

We tested three MacBook Pros: a 13-inch model with Apple's new Touch Bar, which sits above the keyboard; a 13-inch model without the Touch Bar; and a 15-inch model. (All 15-inch MacBook Pros come with the Touch Bar.) All three machines were bought at retail, just like all products rated by Consumer Reports, from sports coupes to countertops. We do this to ensure that the models we test are identical to the ones a consumer would purchase.

The MacBook Pro battery life results were highly inconsistent from one trial to the next.

For instance, in a series of three consecutive tests, the 13-inch model with the Touch Bar ran for 16 hours in the first trial, 12.75 hours in the second, and just 3.75 hours in the third. The 13-inch model without the Touch Bar worked for 19.5 hours in one trial but only 4.5 hours in the next. And the numbers for the 15-inch laptop ranged from 18.5 down to 8 hours. 

Those were just a few of the results; we tested battery life on these laptops repeatedly.

Typically, a laptop's battery life may vary from one trial to another by less than 5 percent. To arrive at our final battery life score we average those measurements together.

However, with the widely disparate figures we found in the MacBook Pro tests, an average wouldn't reflect anything a consumer would be likely to experience in the real world. For that reason, we are reporting the lowest battery life results, and using those numbers in calculating our final scores. It's the only time frame we can confidently advise a consumer to rely on if he or she is planning use the product without access to an electrical outlet.

Battery life is an important attribute for a laptop, and it it represents a significant portion of our overall score. After factoring together our complete test results, Consumer Reports finds that all three MacBook Pro laptops fail to meet our standards for recommended models.

This is a real departure from past MacBooks. Most Apple laptops have scored well in our battery test, typically lasting much longer than the manufacturer has claimed. For instance, a previous 13-inch MacBook Pro model lasted an exceptional 19 hours in Consumer Reports testing.

Battery Testing Details

Consumer Reports tests hundreds of laptops each year, using identical procedures in highly controlled conditions.

For the battery test, we download a series of 10 web pages sequentially, starting with the battery fully charged, and ending when the laptop shuts down. The web pages are stored on a server in our lab, and transmitted over a WiFi network set up specifically for this purpose. We conduct our battery tests using the computer's default browser—Safari, in the case of the MacBook Pro laptops.

During the tests, we set each laptop screen to remain on. We use an external meter to set the display brightness to 100 nits—a typical level you might use indoors or out. And, we turn off any automatic brightness adjustment in the laptop's settings.

We also update every computer's operating system before we begin any testing. We began our tests several weeks ago, but repeated the battery tests using macOS Sierra 10.12.2 after it was released. We saw no difference in the results.

Increasingly, we see that the performance of all kinds of products—not just computers and smartphones—can be influenced by software updates. If Apple updates its software in a way that the company claims will substantively change battery performance, we will conduct fresh tests.

Once our official testing was done, we experimented by conducting the same battery tests using a Chrome browser, rather than Safari. For this exercise, we ran two trials on each of the laptops, and found battery life to be consistently high on all six runs. That's not enough data for us to draw a conclusion, and in any case a test using Chrome wouldn't affect our ratings, since we only use the default browser to calculate our scores for all laptops. But it's something that a MacBook Pro owner might choose to try.

Consumer Reports has shared diagnostic files pulled from all three computers with Apple in the hope that this will help the company diagnose and fix any problem. We will report back with any updates.