Firefighters hope to bring a 'big battery' fire in Victoria under control soon, as investigations begin looking into how the blaze started.
A Tesla battery bank caught fire while it was being set up in Moorabool on Friday morning, and then spread to a second battery.
The fire has continued to burn throughout the weekend and into a fourth day on Monday.
Country Fire Authority incident controller Ian Beswicke said crews were opening the doors of each battery bank and checking for fire, smoke or any increase in temperature on Monday afternoon.
Mr Beswicke told AAP:
"I'm hoping by the end of the day we've got them all open, there's no fire and we can put an 'under control' on it."
Mr Beswicke said the fire was particularly challenging due to the complex nature of the battery site.
"This is the first mega pack fire that's ever happened in the world, is our understanding.
"They are difficult to fight because you can't put water on the mega packs ... all that does is extend the length of time that the fire burns for."
Firefighters have been taking advice from experts including Tesla, the battery's creators, and UGL, who are installing the battery packs.
Mr Beswicke said:
"The recommended process is you cool everything around it so the fire can't spread and you let it burn out, and we're almost at the point where we think it's all burned out."
As soon as it's safe, a group of investigators from a range of agencies, including Energy Safe Victoria, police and Tesla, will start physically examining the area to determine the cause.
The site is slated to become the biggest battery in the southern hemisphere and forms part of a state government push to transition to renewable energy.
But the fire has sparked calls for the government to conduct its own probe into what happened before pressing forward.
Shadow energy minister Brad Rowswell said:
"If Labor's renewable energy solutions go up in flames even before they're fully operational – what hope do Victorians have that this government will be able to effectively manage the renewable energy transition?"
The 300MW battery project is being produced by French renewable energy giant Neoen and was registered with the energy market operator on July 28.
Neoen Australia managing director Louis de Sambucy said there were no injuries to workers and confirmed the site had been disconnected from the grid with no impact to electricity supply.
He said investigation preparations were underway and physical inspections would begin once the CFA allowed for it.
The state government has been contacted for a response.