Tesla is on the verge of keeping its promise of building the world’s largest lithium-ion battery in South Australia to store renewable energy in 100 days. The battery is now “fully installed”, and will undergo final testing for regulatory requirements before being launched next week, the local government said on Thursday.

Tesla founder Elon Musk (pictured above) had promised to not charge the government if his team did not meet the deadline. The 100-day deadline ends in January.

The company had won the bid for the 129-megawatt-hour battery in July, and it was already halfway through when the countdown actually began with the signing of a grid connection agreement on September 29.

The Tesla Powerpacks are attached to a wind farm run in the state of South Australia by a French company. The Powerpack system is an attempt to ease the state’s severe energy crisis. South Australia is the country’s most wind power-dependent state, and had announced a $550-million energy plan to improve its electricity services.

Power supply from conventional energy sources are expected to be tight this year, the country’s energy market operator has warned.