Tesla Motors Inc. had an obligation to pay a total of about $1.7 billion to Japan's Panasonic Corp. as of Sept. 30 for electric vehicle battery cells made at Tesla's gigafactory in Nevada, the carmaker said in a regulatory filing.

Panasonic, Tesla's longstanding battery partner, agreed in 2014 to invest in equipment, machinery and other manufacturing tools at the gigafactory, which will make cylindrical lithium-ion cells for Tesla's cars.

Tesla has said it expects to start making batteries at the $5 billion plant by the end of the year.

The batteries will be used initially in Tesla's energy products and later in its cars.

Panasonic, which plans to contribute up to $1.6 billion to produce battery cells for Tesla, cut its annual profit forecast on Monday after bringing forward some of its investment in the gigafactory in anticipation of strong demand.