Power reserve is important in two ways. In a self-winding watch, when you’re wearing it, you don’t need a long power reserve because you’re constantly winding it with your own movements, and even the minimum power reserve of 38 hours is plenty enough to keep it going when you take the watch off to go to bed. But if you leave it in your drawer for the weekend, 38 hours isn’t enough to keep it going during the weekend, and you’ll have to adjust time and date when you put it back on your wrist on Monday morning. In a hand-wound watch, the higher the power reserve, the less frequently you have to wind it. The crown stem is one of the most delicate parts of the watch and so the less you use it the better.

You may well ask, what’s the point of a hand-wound watch when we have self-winding technology? In part, tradition, and in part, a hand-wound watch doesn’t have an oscillating weight, and so more of the movement can be seen through a transparent caseback window.
Here are some examples of the quest to attain increasingly long power reserves.

Certina DS-1 Powermatic 80 – 80 hours power reserve

The Certina DS-1 Powermatic 80 shows the way in which Swatch Group has been developing its low-cost self-winding movements. The ETA Powermatic 80, CO7.111, is part of ETA’s new generation of movements, in which power reserve is doubled from the 40 or so hours of the class ETA 2824 movements to reach 80 hours. This increase is attained in two ways: by reducing balance wheel frequency from 4 Hertz to 3 Hertz, and by a mainspring made from a special alloy made by Swatch Group company Nivarox. Its high flexibility makes it possible to reduce the diameter of the central mainspring arbour and increase the total length of the spring. There remain the questions on the materials used for certain components (partly because the Sistem 51 movement, which has a number of parts in plastic, was developed from the same research that created the Powermatic 80). Certainly the movement is made using the Arcap anti-magnetic alloy, copper, nickel and zinc. It is used for watches by other Swatch Group brands such as Tissot. Price of this piece is 725 Swiss francs, £530, €710. I twill be available from July 2016.

Glashütte Original Senator Excellence – 100 hours power reserve

The Glashütte Original Senator Excellence was presented in March 2016, and the three models –two very classical daytime watches in steel or red gold, and a black-dial watch with steel case and luminous dial indications, pilot’s watch style – are powered by a completely redesigned in-house movement Calibre 36. As Glashütte Original CEO Yann Gamard said during the presentation of the new movement, 100 hours is not a record, neither were they trying specifically to set a new record, but four days is a good compromise, because you can leave the watch in your drawer for the weekend, and it will still be running when on Monday you put it back on. They achieved 100 hours by means of a new Nivarox mainspring – Glashütte Original is a Swatch Group brand and so has access to the same technology as for the Certina DS-1Powermatic 80 mentioned above – of length 68 cm. There is a single mainspring barrel. The gear train was also redesigned to transfer the energy with less friction losses, by virtue of a new tooth design. Price €8,500 including VAT for the two steel versions, and €15,500 including VAT for the red gold version.

IWC Big Pilot’s Watch Top Gun IW502001 – 168 hours power reserve

The IWC Big Pilot’s Watch Top Gun IW502001 is one of the brand’s several watches powered by the self-winding in-house 51111 calibre. It is one of IWC’s largest movements, running at 21,600 vibrations per hour, 3 Hertz. The space available makes it possible to have a comparatively large mainspring, so that power reserve is over 7 days, automatically limited to 168 hours (exactly 7 days) so that the watch runs with optimum precision during the segment of power with sufficient torque. The watch has a power reserve indicator on the dial. Price €14,700 incl. tax, £10,750 including VAT.

Panerai Luminor 8 Days – 192 hours power reserve

The Panerai Luminor 8 Days is powered by the hand-wound P.5000 movement, made entirely in-house, with a power reserve of 8 days, 192 hours. The long power reserve is a Panerai characteristic dating back to its watches made for Italian navy commandos between the late 1940s and early ‘50s, at which time the brand wasn’t making its own movements and used a hand-wound Angelus movement, the Angelus SF 240. The P.5000 achieves its long power reserve, 192 hours, by coupling the two spring barrels in series, with their toothed rims meshing. The twin assembly enables longer, thinner springs to be used, resulting in a longer duration and greater uniformity in delivering energy to the movement. Extra duration is also provided by a balance running at 21,600 vibrations per hour, 3 Hertz. The movement has traditional, very strong construction, with all components mounted between two plates so that only the balance and intermediate wheel are visible – but in any case, the watch has a solid caseback and so its finish can be admired solely by a watchmaker. The entry-level version in steel, PAM 560, costs $6,600.

Bovet 1822 Flying Tourbillon Ottantasei – 240 hours power reserve

This watch is a collaboration between Bovet 1822 and Pininfarina, and it is a tourbillon watch with a power reserve of ten days, an exceptional performance that is justifiably emphasized by a power reserve indicator – through which the mainspring can be viewed – as large as the dial for time functions. The movement is the hand-wound 17BM03MM. The mainspring is 1.04 metres long, providing 240 hours of operation. The long power reserve is in part achieved by a low balance oscillation rate 18,000 vibrations per hour (2.5 Hertz). The price of the titanium version is 160,000 Swiss francs, the gold version 175,000 Swiss francs.

A. Lange & Söhne Lange 31 – 744 hours power reserve

In 2007, when it was introduced, the Lange 31 was the first watch with a power reserve of 31 days. It’s a massive behemoth of a watch, 46 mm in diameter and almost 16 mm thick, very heavy at 275 grams, with two mainspring barrels, each with a spring 185 cm long. Just about as tall as me! So this watch has a total of 3.7 metres of mainspring, which when fully wound delivers a massive force. The watch has a constant-force mechanism to keep it under control and to deliver a regular torque to the escapement. It does it by means of a remontoir spring. Every ten seconds, the mainsprings retension the remontoir spring by 60°, and so this latter spring delivers constant power for the entire duration of the power reserve. Of course it’s much more complicated than this: the system is based on a specially-designed remontoir escapement with two fourth wheels. The balance runs at 3 Hertz, 21,600 vibrations per hour. A. Lange & Söhne had to return to the past for the winding system: a key, inserted into a hole in the caseback. On the dial, the 31-day power reserve indicator is given pride of place. In platinum, the watch costs €166,300.

Rebellion Prometheus – 1000 hours power reserve

1,000 hours power reserve? How long is that? 41 days. So you wind up the watch and you can put it on and it will keep going for a month and ten days. Most mechanical watches run for about 42 hours from when they are fully wound so this piece has about 24 times the power reserve of a normal watch. How did the people at Rebellion achieve it? Six mainspring barrels, connected and wound by means of a miniaturised chain that interconnects them all. The winding system is not a crown, but a square handle – you can see it raised in the photo – that you operate backwards and forwards. The time is shown by two rollers turning in opposite directions. Rebellion are obsessed with racing cars as well as with watches, and the movement of this machine suggests a powerful engine. It is made of aerospace alloy avional to reduce weight, and everything is visible through the massive sapphire crystal. The two microchains that transmit power from the barrels to the movement are the smallest mechanical chains in the world, each 46 mm in length, with 182 pieces. Even the crown is different to most timepieces: instead of pulling it out to set the time, you just press and turn. At 52 mm length and almost 48 mm width, it’s not a watch that goes unnoticed. Just the case has 75 components and the movement another 698. The price is as exceptional as the watch: one million two hundred and fifty thousand Swiss francs.

Hublot MP-05 LaFerrari – 1200 hours power reserve

This watch stems from the Ferrari-Hublot partnership, and its name LaFerrari comes from the eponymous car. The timepiece expresses the concept of power better than any other: the 11 mainspring barrels, providing 50 days power reserve, are lined up at the centre; time, in hours and minutes, is shown to the right, and power reserve on the left. Like the Lange 31, the MP-05 LaFerrari has a special tool for winding. The tourbillon regulator, running at 3 Hertz (21,600 vibrations per hour) is visible on the short end of the watch. The original version of this watch, introduced in 2013, was in titanium with black PVD finish, a limited edition of 50 pieces. Other versions have since been produced. Price about $300,000.

Special mention:

MB&F LM1 Silberstein – cheekiest power reserve indicator

This year’s new version of the MB&F LM1, an artistic collaboration with Alain Silberstein, is bright and colourful. Its power reserve is just 45 hours, with balance wheel in full view and rotating at a dignified speed of 2.5 Hertz, 18,000 vibrations per hour. But, in the context of this article, the colourful feature of this watch is the power reserve indicator in the 6 o’clock position. Silberstein has given it primary colours and simple geometric shapes, but its functioning – rising erect at full power reserve, and gradually dropping down as time elapses – hints at another essential part of male hardware. In very good taste, of course.