Panasonic is studying further investments in battery production at its Gigafactory venture with Tesla.

Japanese financial daily Nikkei reported here earlier on Thursday that financial issues had led Tesla and Panasonic to rethink plans to expand the capacity of Gigafactory 1 by another 50 percent next year, having together invested $4.5 billion in the plant.

The paper said the companies had earlier planned to expand the plant’s capacity to the equivalent of 54 gigawatt hours a year by 2020, up from 35 GWh at present.

“Panasonic established a battery production capacity of 35GWh in Tesla’s Gigafactory 1 by the end of March 2019 in line with growing demand,” Panasonic said.

“Watching the demand situation, Panasonic will study additional investments over 35GWh in collaboration with Tesla.”

Panasonic is the exclusive battery cell supplier for Tesla, which in turn is Panasonic’s biggest EV battery client.

Earlier this month, Tesla reported lower-than-expected car deliveries in the first quarter.