FreeWire Technologies Inc., a California developer of mobile electric-car charging systems, raised $15 million from investors led by oil giant BP Plc’s venture group to commercialize its product and expand its operations and sales teams.

Other investors in the Series A round included Volvo Cars Tech Fund, Stanley Ventures and Blue Bear Capital, according to a statement Tuesday. FreeWire’s Mobi chargers can be wheeled out to charge electric vehicles where they’re parked. The company also offers a mobile backup battery-power…