File photo: AFP

Two female US astronauts wrapped up a spacewalk out of the International Space Station (ISS) on Wednesday, replacing batteries on the station's port truss.

Astronauts Christina Koch and Jessica Meir finished their spacewalk at 2:04 p.m. US Eastern Time, which lasted about seven hours and 29 minutes, according to the US space agency NASA.

This is the second all-female spacewalk. Koch and Meir completed the first one in October last year.

They replaced nickel-hydrogen batteries with new lithium-ion batteries that store and distribute power generated by the station's solar arrays on the station's port truss.

The lithium-ion batteries provide an improved power capacity for operations with a lighter mass and a smaller volume than the nickel-hydrogen batteries, according to NASA.

Also, the duo astronauts accomplished a get-ahead task of relocating an additional nickel-hydrogen battery to the external pallet in preparation for next week's spacewalk.

Meir and Koch are scheduled to venture outside the station again on Jan. 20 for a second battery replacement spacewalk.

Spacewalkers in the space lab have till now spent a total of 58 days, 23 hours, and 12 minutes working outside the station.