The Westborough, Mass.-based startup makes Lithium-Ion batteries rated for 1,000 charge-discharge cycles, meaning it can hold most of its capacity for at least three years. Conventional Lithium-Ion batteries are rated at 300 cycles and start degrading after the first year of use.

Boston-Power’s laptop batteries also recharge faster, expend less heat, and are safer than mainstream batteries, says CEO Christina Lampe-Onnerud.

The company, which is backed by $125 million in venture capital funds, currently has an exclusive deal to supply its long-life batteries to Hewlett-Packard Co.

HP began offering Boston Power’s batteries for a trio of its business laptops and a wider variety of consumer models this spring . HP Presario M2000 battery packages the batteries under the Enviro moniker, which the company said which highlights their “green” credentials.

HP is now selling the Enviro as a replacement battery .HP presario V2000 battery The product is available on the HP site.

HP charges $150 to $170 for an Enviro battery, which Lampe-Onnerud said is $20 to $40 more than equivalent 6-cell batteries (the Enviros are currently discounted by 25% as part of HP’s Labor Day Sale).

HP recently began letting enterprise and consumer buyers configure notebooks online with Enviro batteries, HP Presario V3000 battery said Lampe-Onnerud. HP will soon begin shipping notebooks into its distribution channels with an Enviro battery instead of a conventional one, she added.

Both moves should boost shipments of the Enviro, Lampe-Onnerud said. However, she declined to disclose sales figures for the battery.

Lampe-Onnerud also said that the company expects to eventually sign deals with other PC vendors. “We had to choose a champion — and that is HP,” she said. “But I’m sure you’ll see the batteries come through other brands.”

By year’s end, Boston Power plans to start selling its batteries into vertical markets such as healthcare, HP presario V4000 battery military and homeland security for a variety of potential applications, such as medical carts in hospitals and electronic military gear, said Lampe-Onnerud.