Mechanical watches don't have batteries; their power comes from stored energy inside the movement's barrel. The barrel is a large gear that contains a coiled mainspring and a flat steel spring. The full name is the. The mechanical watch with the longest power reserve in the world is Vacheron Constantin'sgroundbreaking Traditionnelle Twin Beat Perpetual Calendar. It has an astonishing power reserve of 65 days! When it debuted. In 2019, independent watchmaker Rebellion partnered with Zenvo, a hypercar manufacturer, to create the T2m Zenvo, which has a 1,400-hour power reserve. This racing-inspired watchhas plenty of automotive detail. Until Vacheron Constantin eclipsed it in 2019, Hublot held the record for the watch with the longest power reserve. In 2013, Hublot unveiled the MP-05 LaFerrari, which had a groundbreaking 1,200 hours, or 50 days, of power re. It's difficult for a new, independent watch brand to make an instant splash with its first watch. But watchmaker Stéphane von Gunten honed his craft at the best companies in the world, including Patek Philippe, Girard-.