Dell has announced a new range of Latitude laptops, including one that the company claimed would provide 19 hours of battery life.

The company's Latitude E6400 runs for as much as 10 hours on a single nine-cell battery, and an additional battery that snaps on to the bottom of the laptop adds as much as nine hours of battery life, according to Dell. That gives users close to a full day of laptop use without carrying an AC adapter to recharge the batteries.

Dell has developed proprietary technology to boost battery life in the laptop, said Jeff Clarke, senior vice president and general manager at Dell. The technology focuses on making components suck less power from the battery, Clarke said. For example, the refresh rate of a screen is reduced under certain conditions. Dell needed to develop related software and work with component manufacturers to enable these capabilities.

The company has also added those power-saving features to other Latitude models, but a Dell spokesman wouldn't say whether they would also be available on the Inspiron line of consumer laptops. The battery life was measured using standard industry benchmarks, Dell officials said.

The Latitude E6400 comes with a 14.1-inch screen and runs an Intel Core 2 Duo processor. It can have as much as 8GB of RAM and 250GB of storage. The system comes preloaded with Windows Vista, with an option to downgrade to Windows XP. It is priced starting at US$1,139 (£709). The Latitude E6500, a similar laptop with a larger screen, was also announced, starting at $1,169 (£729). Both systems are available immediately.

Dell has also added some other power-related enhancements to new laptops and said it would offer a smaller and lighter AC adapter that enables batteries to recharge more quickly. Some of the new Latitudes will also be able to recharge consumer electronics, such as a cell phone, via USB without the laptop being switched on, according to the company.

In addition, Dell announced new ultraportable laptops, including the Latitude E4200, which the company said is its smallest and lightest commercial laptop to date. It comes with a 12.1-inch screen and weighs just under 1kg. Another ultraportable, the Latitude E4300, has a 13.3-inch screen and weighs 1.5kg. Both are powered by Intel Core 2 Duo ultra-low voltage (ULV) processors running between 1.40GHz and 2.40GHz. Pricing information has not been announced, but the laptops will be available in the coming weeks, a Dell spokesman said.

Future ultramobile Latitudes could feature Dell's On technology, with which users will be able to access the web, email messages and contacts without loading the main operating system, the company said. Dell previewed the technology at the event but didn't give complete details.

Dell rounded out Tuesday's announcements with budget and semi-rugged Latitude laptops. The E5400 and E5500 laptops, available immediately, come with a variety of screen sizes. The semi-rugged E6400 ATG laptop, which meets the US Army's standards to withstand dust and humidity, will be available shortly.

Dell has seen its laptop shipments grow since it signed up retailers worldwide to sell them, a move away from its web-based sales model. It is the second-largest PC retailer behind HP, shipping 11.56 million units in the second quarter for a 16.4 percent market share, according to IDC. That represented a 21.4 percent year-over-year increase, IDC said.