Mercedes has identified a fault in its F1 power unit battery as the likely cause of the costly retirements that hit George Russell and Kimi Antonelli, and the team is working on a permanent fix. Russell’s Canadian Grand Prix ended while he was leading, while Antonelli retired from second place in Barcelona after a similar failure. Technical director James Allison said the battery was the source of the reliability issue after examining Antonelli’s car.
Allison said the two failures were not identical, but both came from the same broad area of the battery. Mercedes is developing new modules to improve reliability across its cars, and it has already narrowed down most of the risk areas. The team is taking a cautious short-term approach while engineers work toward a lasting solution, but it has not given a timeline for the repair. Mercedes heads into four race weekends in five weeks, starting with Austria next weekend.
The problem has hurt Mercedes’ constructors’ title fight, with team principal Toto Wolff saying after Barcelona that the team could not afford repeated DNFs and would investigate the issue thoroughly. The retirements cost Mercedes potential podium finishes while its cars were running in strong positions. Mercedes did not say whether McLaren’s recent electrical issues were linked to the fault it found, and former driver David Coulthard said reliability problems could worsen as the 2026 season progresses, even as he still viewed Mercedes as having the strongest overall package on the grid.
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