The nocturnal gauging test was a prelude to the start of the full testing and commissioning programme on the Grand Central - Centenary Square section, which is due to begin in October.
The Midland Metro Alliance says the test run represents the first occasion in Britain a tram has run under battery power on a modern light rail line specifically built without catenary.
The 2km two-phase extension is being planned, designed and built by the Midland Metro Alliance on behalf of Transport for West Midlands (TfWM).
The £70m first phase between Grand Central and Centenary Square is due to open in December, with the remainder of the extension to Edgbaston scheduled for completion in 2021.
Construction started on Phase 1 in June 2017 and tracklaying began on the Birmingham Westside extension in February.
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