Apple is working with Consumers Reports to figure out why the reviews site's battery test results for the newdo not match the gadget giant's lab tests and field data.
Consumer Reports published a surprise report Thursday saying it could not recommend any new MacBook Pro model due to its erratic, if not bad battery life.
"The MacBook Pro battery life results were highly inconsistent from one trial to the next," Consumer Reports said.
This is the first time a MacBook hasn't received a "recommended" designation from Consumer Reports.
Apple Senior Vice President Phil Schiller followed up with a tweet late Friday saying Apple is "working with CR to understand their battery tests. Results do not match our extensive lab tests or field data."
In his tweet, Schiller linked to a story from iMore that says Consumer Reports was just going for a pre-Christmas headline and should have done more testing.
Consumer Reports' review says that in-house testing revealed wild fluctuations in battery life for unplugged MacBook Pro computers. In the case of the, for example, battery life ranged from 19.5 hours to just 4.5 hours. Apple says the devices should operate for up to 10 hours between charges.
"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," Consumer Reports said in a blog post about its MacBook Pro rating.
It ended up giving the 15-inch MacBook Pro a score of 56 points out of 100. The 13-inch versions with and without a Touch Bar got 40 and 47, respectively, out of 100.
"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 Consumer Reports post reads. "The web pages are stored on a server in our lab, and transmitted over a Wi-Fi 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."
Apple didn't immediately respond to a request for more information about battery life tests and Schiller's tweet. Consumer Reports also didn't immediately respond to a requests for comment and confirmation that it's working with Apple.