With all of the arcane complications available in mechanical watches, the power reserve, or réserve de marche, stands out for its straightforward practicality. Just as a car’s fuel gauge measures gas left in the tank, a power reserve keeps track of when a watch’s movement is running on empty and needs refueling. Thus you know how much running time is left in an automatic watch that is at rest or how long a manual-wind watch can operate before it needs a recharge. And because accuracy diminishes as the mainspring winds down past half capacity, a power reserve can help to keep better time.
Lately, watch designers have challenged the typical power-reserve display—a hand that sweeps along an arc from high to low—with such novel concepts as the number 12 on JeanRichard’s 2012 Diverscope, which drains the color white as power wanes. Jaeger-LeCoultre’s new AMVOX7 Chronograph has a radial display of red arcs positioned around the periphery of the dial at 12 o’clock.
Panerai has used a linear power reserve display at 6 o’clock since the 2005 debut of its brawny eight-day power reserve. This year, the brand’s PAM 530 Luminor 1950 Rattrapante 8 Days Titanio ($27,200) combines the power reserve with a split-seconds chronograph, also called a rattrapante, with a vertical clutch and twin column wheels—hallmarks of quality construction. The split-seconds can time two entrants in a race who begin, but don’t finish, together. While the average power reserve is about 40 to 50 hours, Panerai’s P.2006 movement reaches eight days by using three barrels, each housing a mainspring. A. Lange & Söhne, however, takes the prize for the longest power reserve with 2007’s Lange 31 that runs for a full month thanks to two large stacked barrels containing a pair of six-foot-long mainsprings.
A second barrel enables Franck Muller’s Vintage 7-Days Power Reserve to deliver a week of staying power. The Deco-infused Curvex case and retro dial design are matched with an unconventional power reserve display showing a numeral indicating the number of days remaining in a window at 11 o’clock. The model houses the company’s first wholly in-house-made movement and is available in steel or 18-karat pink gold in three sizes with your choice of a white or black enamel dial ($12,600 to $26,500). A sapphire crystal case back showcases the manual movement with 213 components including 27 rubies.
And for those who adhere to the less-is-more principle, Carl F. Bucherer’s classic Manero BigDate Power ($16,600 in 18-karat rose gold and $5,800 in stainless steel) keeps it simple with a clean, uncluttered dial that immediately draws your eye to its arced power reserve display that spans from 8 o’clock to 5 o’clock. For optimal precision, be sure to fill ’er up well before it hits the red zone.
Visit panerai.com, franckmuller.com and carl-f-bucherer.com.