What is the most accurate wrist Watch without battery commercial available ?

A few thousand years, Chinese used water to power a Clock Tower, though time keeping was not too accurate.

When we  developed the use of pendulum ‘s potential energy to drive a spring coil to save up energy and the pendulum could form a time keeping device as we called Clock.

Boluva’s Accutron is the early version of low frequency electronic Watch,  then Seiko's Quartz watch adopting the much higher frequency of vibration and this has better accuracy.

Rolex launched Oyster Quartz Ref 3100 with Beta 21 movement back in 60s.

Accuracy of Rolex OQ is  about 0.33 second per month, but it needs a battery to drive the whole mechanical movement and IC Mmodule.

Atomic clocks use an electromagnetic signal of light emitted at an exact frequency to move electrons in caesium atoms.

The physicists built their ytterbium clocks using about 10,000 rare-earth atoms cooled to 10 micro Kelvin (10 millionths of a degree above absolute zero) and trapped in an optical lattice made of laser light.

Another laser that "ticks" 518 trillion times per second triggers a transition between two energy levels in the atoms. The clock's high stability is owed to the large number of atoms.

US scientists say they have built the world's most precise clock, whose ticking rate varies less than two parts in one quintillion!

NIST's ultra-stable ytterbium lattice atomic clock Photo: AFP

How about a Mechanical Watch ?

Well Rolex and Patek Philippe claims to be accurate , but that is in the range of +4 to – 2 seconds per day!

That is nothing comparable to any of the electronics watches… Though, they are not cheap, typically USD$4,000 upward for Rolex and a couple of times more for Patek Philippe.

Quartz watch is not accurate enough, an ordinary Quartz Watch may have variation about 1 second a month.. that is about 15 Seconds a years.

Anyway, we are talking about second to minute a year, which is nothing to the watch shown here.

Citizen Q&Q Radio Controlled Solarmate wrist watch

That it claims the time is actually aligned in with the Radio station signal Beacon, time accuracy is said to be +/- 1 second in 10,000 years!

Price Yen 9,075  that is about HKD$500!

Most accurate watch money can buy, and it only about US$70!

It is solar cell driven so we need no battery!

It does not need time adjustment as it will update with the beacon radio signal and update itself.

So by right you can buy this watch and you need no adjustment for rest of your life!

It is so quiet, no battery needed, probably no need to service, no need to readjust the time.... what else do you expect more from a watch?

HK Snob