Call it the Achilles' heel of laptop technology: battery life. While considerable improvements have been made in processor speed, screen quality, and wireless connectivity, batteries seem to be the one lagging area in mobile computing. That's not to mention the largest component recall in the history of the PC last year, when thousands of laptop batteries were recalled by manufacturers because of the potential for spontaneous fires.

There is some good news, however. While alternative sources of power --such as fuel cells -- may be a few years off, there are some advancements in lithium-ion battery technology, not to mention CPU breakthroughs, such as dual-core processors, that can also help your laptop last an entire day.

“Batteries are probably the slowest moving technology because it’s chemistry rather than silicon, the latter of which tends to see greater strides,” says Bob O’Donnell, vice president of clients and displays at IDC, a Framingham, Mass.-based technology research firm.

That said, 12-cell batteries are considered top-of-the-line today for laptop users, says O’Donnell. Available as an upgrade among many PC manufacturers such as HP and Dell, a 12-cell battery may extend the life up to 10 hours of use, depending on the applications running: typing in a word processor, for example, is a lot less taxing on the battery than, say, playing a DVD movie or surfing the Internet wirelessly in a hotspot.

“The best way to think of 6-, 8-, 9- or 12-cell batteries is as units of power, like having a toy that takes 12 AA batteries instead of 6 batteries,” explains O’Donnell. “The higher the number, the longer the battery life.”

But there’s a trade-off, as 12-cell batteries are generally larger than the regular 6- or 8-cell that ships with the unit, therefore users can expect a protrusion on the bottom or back of the laptop. While this might be the case today, O’Donnell says some PC manufacturers might figure out a way for multi-cell batteries to be less obtrusive. “As we need less space for circuitry because of advancements in components, theoretically, there can be more space available for a [bigger] battery.”

Alternatives, CPU advancements

Some manufacturers offer a different solution, such as a thin battery that lies along the entire bottom of the computer or the ability to insert two “bar” batteries instead of one.

HP’s Compaq 2710p tablet notebook, for instance, offers roughly 5.5 hours with its standard battery, but more than 12 hours when coupled with HP’s thin extended run time battery.

“Polymer lithium ion cells have now become viable for notebook PC applications,” explains Kevin Clancy, senior notebook PC commodity engineering manager at Hewlett-Packard. “They allow for much slimmer battery designs, such as the 2710p extended run time battery, and offer similar discharge capacity.”

On conventional lithium ion, "we see also continuous improvements in design and chemistry to add incremental discharge capacity,” adds Clancy.

Clancy says laptop owners will likely see a 10 percent improvement in battery life in 2008.

Laptops with dual-core processors, such as those powered by Intel Core 2 Duo technology, may offer up to 40 percent more energy efficiency than past processors, which results in greater battery life.

“CPUs are getting much smarter today, too, where they sip battery power instead of gulping it,” says O’Donnell.