I love smartphones. No, really I do. If my smartphone were a girl I would totally marry her. I'm a latecomer to them, but now I realise I don't really need to do conversations over dinner. I don't even really need friends. The only letdown is the battery. How is it that they can put a man on the moon but phone batteries can only endure six hours of heavy use? Battery power, or power reserve, on watches is also an issue, with most mechanical watches maxing out at just over 40 hours. Still, there are a few that make a virtue out their longevity and this week we look at three that last the course.

First up we have the marvellously named and charmingly designed Zeitwinkel 273° (right). There are no obvious clues as to why Zeitwinkel has called this watch the 273° - in fact, all of its watches seem to be named after a number of degrees, so if anyone happens to know why please do e-mail in. Despite its obscure name, however, this is a wonderfully designed and balanced watch with a hefty 72-hour power reserve pumped out by the automatic ZW 0103 movement.

The dial neatly displays hours, minutes and small seconds, the latter at the six o'clock position, but the eye is drawn to the power-reserve indicator, placed between the one and two o'clock positions. There is also a large date window at the 10 o'clock position. The stainless-steel case is sized at 42.5mm and the watch comes with a hand-sewn calf-leather strap. The Zeitwinkel 273° is priced at about HK$80,000.

Next we have the 92-hour monster that is the Antoine Martin Slow Runner (below right). Slow Runner by name, slow runner by design, the AM36.001 movement has an enormous 24mm balance wheel that slows this watch down to one beat per second.

Most mechanical watches today operate at eight or 10 beats per second and the rule of thumb is that the faster a watch beats the more accurate it is, so the Slow Runner is unusual in the extreme. But why? Well, ask Antoine Martin and it will tell you it's because it can, and that it's more about the engineering challenge of creating a watch that is accurate but still slow, as it were.

Highlighting the sluggish pace, the dial is dominated by a large seconds subdial that moves rather slowly. The face also has a power-reserve indicator. The case is sized at 42mm and the watch comes in a steel version, priced at HK$160,000, and a rose-gold model, priced at more than HK$280,000.

Finally, we have the Patek Philippe 5200G Gondolo 8 Days Day & Date (below left). Eight days equals 192 hours, which should impress even the most jaded watch spotter. There are mechanical watches out there that can go to more than 10 days but very few look this good. The 5200G combines technical expertise with Patek Philippe's mastery of design and balance, with the watch displaying an incredible amount of information but still maintaining a classic art-deco elegance.

At the 12 o'clock position is the prominently displayed power-reserve indicator and at the six o'clock position the day and date, as well as running seconds indications. The eye-catching softened Gondolo case is sized at 37.4mm by 46.9mm and is made of white gold, with the strap in lovely navy alligator leather. The Patek Philippe 5200G Gondolo 8 Days Day & Date is priced at HK$413,400.