Catherine King said the first stage of light rail had been transformative for the capital and showed the ACT had foresight in making sure Canberra was equipped with a modern public transport system.

"These are the sorts of partnerships that an Albanese Labor government wants to have with our state and territory partners," Ms King said.

"We want to be able to work collaboratively to ensure we actually increase public transport offerings across the country."

The federal government's stance under Labor has significantly shifted, in the surest signs to date it will back the next stages of the project.

Ms King spoke at the Mitchell light rail depot on Tuesday morning, when the ACT and federal governments announced a $181.2 million contract for five more light rail vehicles and battery retrofitting for the existing fleet.

ACT Transport Minister Chris Steel said the funding for the contract - which also includes a depot expansion to house and maintain the larger fleet - would be funded from money already appropriated for the project.

Ms King said the federal government would bed down the detail of a previous $132.5 million Commonwealth commitment to the project.

"As we head into the May budget, I'm sure the ACT government will want to talk to us about our future funding commitments, whether it's for public transport or other road or other infrastructure projects in the ACT," she said.

"The October budget is where we're focused on delivering the election commitments we made here, particularly election commitments in relation to active transport."

Asked if the ACT government would pursue the federal Labor government to revive a dropped 2019 election commitment for $200 million towards light rail, Mr Steel deflected and said he would continue discussions with the Commonwealth.

"This is a really collaborative relationship that we're building here and it's been a vast difference to what we experienced under the previous Coalition government," he said.

Major Projects Canberra's chief projects officer, Duncan Edghill, said engineers were confident the new batteries could be retrofitted to the existing fleet with no issues.

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Similar model light rail vehicles, built by the same firm, have had cracks around the bogey boxes.

A detailed inspection found no evidence of the issue in Canberra, and confirmed differences in vehicle design gave transport authorities confidence the ACT fleet would avoid the issue.

"Our engineers, of course, have been working very closely with Canberra Metro and with the vehicle supplier, CAF, around the technical requirements for those vehicles, including the batteries that will be placed on the roof, the additional weight and systems that that incorporate," Mr Edghill said on Tuesday.

"But we're delighted and very confident that the new light-rail vehicles we're purchasing today will perform as well if not better than the vehicles that are already performing so well on the Canberra fit."

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