Brian Snyder / Reuters Tesla CEO Elon Musk has visited South Australia.

Tesla founder and billionaire boss Elon Musk has revealed construction on the world's most powerful lithium iron battery has hit the halfway mark. Musk has boldly pledged to build the huge battery in South Australia within 100 days or it's free. The deal for the 100 megawatt battery was signed on Friday, kicking off the start of the 100-day deadline for Tesla to complete construction of the huge power storage unit.

Entrepreneur Elon Musk is on track to deliver on his promise to install the world's largest battery in South Australia. #9Newspic.twitter.com/QgUNUy9E8I — Nine News Australia (@9NewsAUS) September 29, 2017

US-based Tesla, best known for its cutting edge electric vehicles, will operate the massive battery on behalf of French wind farm developer Neoen at an estimated cost of $50 million to the SA government. But the government only pays if Musk can deliver the project on time. "The interconnection agreement has been approved by Australian Energy Market Operator (AEMO) and has just been signed," Tesla said in a statement. "Tesla and Neoen now have 100 days to complete the largest lithium-ion battery storage project in the world. It will help solve power outages, reduce intermittencies and manage summertime peak load to support the reliability of South Australia's electrical infrastructure."

The clock is ticking for Tesla owner Elon Musk to make good on his promise to build the world's biggest battery in South Australia. #9Todaypic.twitter.com/kygBPtxR9w — The Today Show (@TheTodayShow) September 29, 2017