CANBERRA, Australia (AP) — An official says Tesla Inc. chief executive Eon Musk is on track to deliver on a promise to build the world's biggest lithium-ion battery in the Australian Outback within 100 days.

Musk promised to build the 100-megawatt battery within 100 days of the contracts being signed at the end of September or hand it over to the South Australia state government for free.

Audrey Zibelman, chief executive of Australian Energy Market Operator Ltd., which manages the Australian electricity grid, said on Tuesday she expected the battery would be ready by Friday.

State Premier Jay Weatherill announced last week that Tesla had finished installing the battery power packs near Jamestown, 200 kilometers (120 miles) north of the state capital Adelaide.

Tesla partnered with French renewable energy company Neoen on the battery.