Battery making startup Boston Power is more than tripling production of its Sonata laptop battery, a device that offers faster charging and longer life than conventional lithium-ion batteries, it is due to announce Thursday.

Boston Power has also struck a manufacturing partnership with Taiwan's GP Batteries, which will begin making the cells to supplement current production at China's HYB Battery. GP will produce around 1 million cells per month, said Christina Lampe-Onnerud, founder and CEO of Boston Power. HYB currently produces between one third and one half that amount, she said.

The Sonata battery was a hit when it was unveiled at the Demo 2007 conference in January 2007 because, according to Boston-Power, it gets over some of the main frustrations laptop users have with their battery packs. Namely it can be charged to 80 percent of total capacity in 30 minutes so even on a short lay-over a meaningful amount of power can be recharged into the battery and it should also last the average three years that people keep their laptops without a noticeable degradation in performance.

In light of a series of high-profile problems and recalls of lithium-ion batteries, Boston-Power is also pushing safety. It says its Sonata battery uses less reactive chemicals and has a series of protective controls that make it safer than competing batteries.

With the extra production, Boston-Power will be looking to pick up customers for the Sonata batteries. It has already been working closely with Hewlett-Packard.

"We are delighted with the response from the market. Interest is really, really large" said Lampe-Onnerud. "We have worked with top-tier notebook makers for several years and they remain extremely engaged. Many have already qualified our system but we're a small company so we have to be selective about who we work with."

Boston-Power has also closed a third round of financing for $45 million, which it will announce Thursday. The round, led by Oak Investment Partners, also included additional money from existing investors Venrock Associates, Granite Global Ventures and Gabriel Venture Partners. The latest investment brings to $68 million the total amount of funds raised by Boston-Power.