Japanese electronics giant and battery manufacturer Panasonic has invested $30 million in Tesla Motors, the U.S. automaker best-known for its all-electric luxury sports car, both companies announced Thursday.

Per the terms of the deal, Panasonic, which already has a working relationship with Tesla through their battery pack collaboration, purchased Tesla common stock at $21.15 per share, acquiring approximately a 2 percent stake in the company.

Tesla and Panasonic had an existing relationship before today, signing a deal in January to develop lithium-ion battery packs for Tesla cars.

Tesla, which also builds power trains for use in electric vehicles in addition to manufacturing cars, has previously used battery components from a variety of companies. But the company announced Thursday that it "has selected Panasonic as its preferred lithium-ion battery cell supplier for its battery packs."

The investment coincides with Panasonic's changing dynamic and vow to reshape itself around new core businesses. It's been expanding its battery business into EV batteries since 2008, is in the process of overhauling its lithium-ion battery cell research and production facilities, and announced in 2009 that it would invest $1 billion in developing products focused on green tech by 2012, including technology for home-energy monitoring systems.

The deal is a feather in the cap of Tesla, a relatively new car company that has been slowly building a following and brand, but until August 2009 had not yet turned a profit.

"It is an honor and a powerful endorsement of our technology that Panasonic, the world's leading battery cell manufacturer, would choose to invest in and partner with Tesla," Tesla co-founder and CEO Elon Musk said in a statement.

Panasonic is not the only stalwart to put money into the start-up car company.

Toyota invested $50 million in Tesla in June shortly after Tesla's initial public offering. The two companies signed a deal under which Tesla will produce two car models for the Japanese automaker, and to that end both have invested in a new Tesla factory in the U.S.

Tesla's assembly plant, which opened in Fremont, Calif., last week, will produce those cars for Toyota as well cars for the Tesla brand. The new manufacturing plant was converted from a closed New United Motor Manufacturing (NUMMI) factory and will produce Tesla's Model S, an all-electric sedan that is expected to have a larger reach than the company's flagship model, the Tesla Roadster luxury sports car.

Tesla has also expanded into making power trains for other automakers, signing a partnership with Daimler to make the power train for 1,000 of its Electric Smart EVs.