By Julia Love and Alexandria Sage

SAN FRANCISCO (Reuters) - Apple Inc (AAPL.O) is investigating how to charge electric cars, talking to charging station companies and hiring engineers with expertise in the area, according to people familiar with the matter and a review of LinkedIn profiles.

For more than a year, Silicon Valley has been buzzing about Apple's plan to build an electric car. Now the company appears to be laying the groundwork for the infrastructure and related software crucial to powering such a product.

The moves show Apple responding to a key shortcoming of electric vehicles: "filling up" the batteries. A shortage of public charging stations, and the hours wasted in charging a car, could be an opportunity for Apple, whose simple designs have transformed consumer electronics.

Apple, which has never publicly acknowledged a car project, declined to comment for this story. Neither the LinkedIn profiles nor sources said specifically that Apple was building charging stations for electric cars.

But automotive sources last year told Reuters that Apple was studying a self-driving electric vehicle (EV), as the Silicon Valley icon looks for new sources of revenue amid a maturing market for its iPhone.

Apple is now asking charging station companies about their underlying technology, one person with knowledge of the matter said. The talks, which have not been reported, do not concern charging for electric cars of Apple employees, a service the company already provides. They indicate that Apple is focused on a car, the person added.

Charging firms are treading carefully, the person added, wary of sharing too much with a company they view as a potential rival.

It is unclear whether Apple would want its own proprietary technology, such as Tesla Motors' (TSLA.O) Supercharger network, or would design a system compatible with offerings from other market players.

Several charging station suppliers contacted by Reuters declined to comment about any dealings with Apple, which typically requires potential partners to sign non-disclosure agreements.

Arun Banskota, president of NRG Energy Inc's (NRG.N) electric vehicle charging business, EVgo, did not respond directly to questions about Apple, but said repeatedly that his company was "in discussions with every manufacturer of today and every potential manufacturer of tomorrow."

Apple has hired at least four electric vehicle charging specialists, including former BMW (BMWG.DE) employee Rónán Ó Braonáin, who worked on integrating charging infrastructure into home energy systems as well as communication between EVs, BMW and utilities, according to a LinkedIn review.