Watching a Blu-ray movie in all its high-definition glory on your laptop may finally become an affordable prospect this year. Just don't wander too far from a power outlet.

With the Sony-backed HD format emerging victorious from a two-year showdown with Toshiba's HD DVD, many laptop manufacturers are now scrambling to add Blu-ray drives in their desktop and notebook lineups. Next month, Dell will even introduce a sub-$1,000 Blu-ray notebook, according to Brian Zucker, a technology strategist for the company.

But the promise of viewing an increasing variety of HD movies on your laptop may be overshadowed by ongoing concerns over the technology's vampiric effect on battery life. Indeed, if the first generation of Blu-ray equipped laptops are any indication, you might not get more than halfway through that movie before running out of juice completely, analysts say.

"Blu-ray battery life is obviously a huge concern," says Yankee Group analyst Josh Martin.

"If you bought an iPhone and you couldn't watch a two-hour movie, which you barely can now, that would be a huge problem," Martin continued.Granted, batteries suck (along with other annoyances like spam filters and plastic packaging). That's largely because there is no Moore's Law for batteries. If battery power capacity improves 1 percent a year, that's considered pretty good. Batteries are more often afterthoughts for an industry obsessed with cramming as many new features into a notebook as possible.

Introducing Blu-ray drives to the mobile mix certainly isn't going to help matters. For now, the laptop manufacturers that have offered Blu-ray drives have also avoided revealing the precise effects of Blu-ray playback on battery life. That's probably for a very good reason, as some claim battery life can top out at one hour in some cases.

"The laser that runs the show [in Blu-ray players] is a very high-power laser," notes Mercury Research analyst Dean McCarron. That laser is one of the main things that conspire to raise power consumption.

The other part of the equation has to do with the process of decoding data from a Blu-ray disc and turning it into moving images on your screen. When Blu-ray was first introduced, this process was all done in software, which is very taxing on the CPU, eating up processing cycles and power.

"Any time you introduce a new technology like this, the initial products tend to be more power-hungry," McCarron says. "Once you get to a certain point, though, the industry usually starts the refinement process."