One of the biggest issues for any portable device is how it uses power and whether its batteries can run an entire eight-hour day without having to be recharged. Before its release, there were indications from Microsoft staff and from analysts that it would be a very power-hungry device. Part of the problem is that 7-inch screen, which consumes a great deal of power. Different configurations vary depending on the specifications of the machine, but battery life for most UMPCs ranges from 2 to 6 hours.
Michael Gartenberg of Jupiter Research wrote in his blog, "What is missing? Battery life. Right now these machines really need to be sold with a higher capacity battery if you're going to use one as a life style device going through the day."
There are numerous notebooks available today that offer three or more hours of battery life, including ones from Sony, Fujitsu and Motion Computing. Of course, these are all larger form factors and thus able to have bigger batteries included to last longer.
To counteract this issue, Microsoft has tried to finesse things by offering more advanced power management on the UMPC. Like many of today's more advanced multimedia laptops, the unit will have a special quick boot sequence that will bring up an embedded OS to run movies or play music files.
Dustin Hubbard at Microsoft writes in his blog, "The Samsung unit actually has 2 boot modes on a 3 way power switch - On, Off and AVS Multimedia (that's their name for this mode). AVS Multimedia can do near instant on by booting into what appears to be XP Embedded (as far as I can tell that is what they are doing) and allows you to play movies, music and photos without requiring you to boot into full XP. That gives you 2 advantages; presumably better battery life by not having so many services running in the background and fast cold boot startup for media only consumption."