Of all the impressive complications that adorn today’s luxury mechanical timepieces, the power reserve is perhaps the most utilitarian – and well on its way to becoming impressive in its own right. Innovation in timepiece design has become as important as technological innovation, as top brands create new ways to present the functions on a watch. The power reserve indicator is no longer restricted to the conventional high/low arc presentation on the dial.
The réserve de marche indicates when a watch’s mainspring is running out of power and needs to be rewound. The obvious analogy for this is a car’s gas tank running out of fuel. Some car-centric timepieces, such as the Chopard Engine One, actually reference this analogy on the dial, marking the power reserve indicator not with the conventional “+” and “-“ symbols but with “empty” and “full.” The réserve de marche has more than just aesthetic value. The performance of a mechanical watch diminishes as the mainspring winds down, so keeping track of the power reserve is essential – more essential, one could argue, even than a tourbillon, a much more high-profile complication.
Chopard L.U.C Engine One, with a “fuel tank” indicator prominent on the left side of the dial. With a hand-wound tourbillon movement caliber L.U.C 04.02.L, in a brushed titanium case, and a 60-hour power reserve.
Girard Perregaux Chrono Hawk in black Ceramic, with the GP03300-0074 caliber self-winding movement, has a 46-hour power reserve, indicated by a large arrow at 6 o’clock, on a retrograde scale with “UP” and one end and “WIND” at the other.
Greubel Forsey Tourbillon 24 Secondes Contemporain, containing the caliber Tourbillon GF01c , with a 72-hour power reserve. The indicator is expressed in blocks of hours – 18, 36, 54 and 72 – on a black and white index that stands out against the blue background.
Urwerk EMC, a self-adjustable watch, with a special “EMC” caliber and double mainsprings, offering an 80-hour power reserve. It is indicated on the lower left of the dial with a large arrow on a plus/minus retrograde scale.
Hublot Masterpiece MP-05 LaFerrari, with a remarkable 50-day (day!) power reserve on account of its 11 mainspring barrels. It uses an anodized black aluminum cylinder for its power reserve indicator, on the left, which move as you wind the watch.