CAPE CANAVERAL, Fla. — Astronauts are taking a spacewalk to hook up fancy new batteries on the International Space Station’s sprawling power grid.

Commander Shane Kimbrough and Peggy Whitson ventured out Friday morning. It’s the first of two spacewalks over the coming week to energize the station’s aging solar power system.

Flight controllers have already completed much of the work. Using station robotics, controllers in Houston spent the past week replacing decade-old, nickel-hydrogen batteries with better charging lithium-ion ones. Handling all those batteries — each about half a refrigerator in size — was cumbersome and time-consuming.

Now it’s up to Kimbrough and Whitson to wire up the three new lithium-ion batteries, delivered last month. Spacewalkers will plug in three more next Friday.

Whitson now ties the record for most spacewalks by a woman.