In a question-and-answer session on Reddit Wednesday, Microsoft's Surface Pro team ignored most questions about the tablet's battery life, but hinted that the company might sell an add-on battery pack in the future.
Even the team's sole response to battery questions did not spell out the time a Surface Pro would run between charges. Instead, it touted the device as "best in its class" in the category.
"If you compare it to say a MacBook Air, you will quickly see that pound for pound in battery size versus battery life, you will find optimizations that puts Surface best in its class," the team told the Reddit "Ask Me Almost Anything" (AMAA) audience. "That said, we picked a smaller battery to be sure we were able to give you the same performance and to keep it thin."
Apple's 11-in. MacBook Air, the closest Apple product in specifications to the Surface Pro, is marketed with a promise of 5 hours of battery life.
The comparison with the MacBook Air was no accident: Earlier in the week, a top Windows executive made a case for the Surface Pro by comparing its price to that of a dual purchase of Apple products, the 11-in. MacBook Air and the 9.7-in. iPad.
The AMAA took place just hours after reviews of the Surface Pro began appearing on the Web. Depending on the reviewer -- and how he or she tested battery life -- Microsoft's newest tablet lasted from just under four hours to just over five hours.
Most hammered battery life as the Surface Pro's greatest weakness. And some didn't pull their punches. Walt Mossberg of the Wall Street Journal, for example, called it "pathetic."
Microsoft has declined to talk about the Surface Pro's battery life since the device's surprise introduction in June 2012. In December, the company said the Pro's battery would last approximately half as long as the one in the Surface RT, the tablet that runs a limited version of Windows.
That led to speculation that the Surface Pro's battery would run the tablet for about four hours; Computerworld estimated it as 4.7 hours, based on tests of the Surface RT by a pair of consumer watchdogs.
On Wednesday, even after reviews had appeared knocking battery life, the Surface Pro team ignored numerous questions in the AMAA.
"What is the battery life? And why isn't it on your webpage?" one attendee asked.
"The battery life is a major concern. Can you explain why the battery life is so low?" asked another.
The team answered neither.
But it did hint that help might be on the way.
When Reddit members asked about the connectors on the bottom of the Surface Pro, the team said they were for future expansion.
"We haven't announced what they are for but they aren't an accident!" replied the Surface Pro team. "At launch we talked about the 'accessory spine' and hinted at future peripherals that can click in and do more. Those connectors look like can carry more current than the pogo pins, don't they?"
Later during the AMAA, another attendee asked, "Does Microsoft have any plans for an external battery or for a thicker keyboard cover that has an extra battery?"
The reply: "That would require extending the design of the accessory spine to include some way to transfer higher current between the peripheral and the main battery. Which we did..."
The current covers-slash-keyboards -- the Touch Cover and Type Cover, which sell separately for $120 and $130, respectively -- do not include a battery of their own but instead draw power from the Surface.
Surface Pro goes on sale Saturday, Feb. 9 at Microsoft's online store; its 70 retail outlets in the U.S. and Canada; the Best Buy and Staples chains in the U.S.; and some retailers in Canada. The tablet will cost $899 (64GB) or $999 (128GB).
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His e-mail address is firstname.lastname@example.org.