TimeTravel #2: Seiko 8T23-8020 Full-Charge Signal

HomeTime TravelTimeTravel #2: Seiko 8T23-8020 Full-Charge Signal

TimeTravel #2: Seiko 8T23-8020 Full-Charge Signal The world’s first manually wound quartz movement by Tomas RosputinskyDecember 10, 2019 MIN READTimeTravel #2: Seiko 8T23-8020 Full-Charge Signal

Imagine it takes three long minutes to wind your watch. And imagine that the watch you’re winding is quartz powered. Crazy? Meet the Seiko 8T23-8020 Full-Charge Signal.

If you remember our first TimeTravel article about the Tissot RockWatch, you already know we are on a mission to bring often overlooked watches born between 1980 to early 2000 to the spotlight. In this second edition, we are sticking to the quartz. But beware, it’s not your typical quartz watch. Today we take a look at the one of a kind Seiko 8T23-8020 from 1986 that bears the title of the world’s first manually wound quartz watch.

Seiko 8T23-8020

Image source: www.distinctivepurveyor.com

Seiko has two first quartz watches

Recently here on Fratello, we introduced Seiko’s Quartz Astron 50th Anniversary Limited Edition commemorating the world’s first quartz watch born in 1969. So why would Seiko ‚step back‘ more than a decade later and develop a quartz watch that needs to be wound? Just as people had to change worn tires once every few seasons, the same had to be done with batteries in quartz watches. In the mid-eighties, quartz was the standard. Getting rid of old batteries was not easy, so the smart people at Seiko decided to come up with a solution on how to give our environment a little break. And, at the same time, show the world what it’s like to be the first again.

Image source: www.distinctivepurveyor.com

Capacitor vs Battery

In 1986, seventeen years after introducing the first quartz watch, Seiko Instruments Inc. revealed a newly developed 8T23 caliber, the world’s first-hand wound quartz. The principle was pretty simple. By winding the crown, a small electrical generator charges a capacitor, that is subsequently able to power the quartz movement. Thanks to the ‚comfy‘ crown, the capacitor can be recharged repeatedly and the watch owner never has to deal with a dead battery. It is like a predecessor of the Kinetic movements.

A 3-day power reserve

Flipping through the pages in the History of the modern wristwatch book by Pieter Doensen I found a couple of explanations as to why the story of the Seiko 8T23 ended as quickly as it began. ‘To supply the supercapacitor with enough energy for 3 days, several minutes of winding by hand are required.‘ Anthony Kable in his article confirms the story by saying, ‚the designers specified the target of a three minute winding time to go from completely discharged to a full capacitor.’ I guess an original manual to the watch would confirm the fact.

Image source: www.distinctivepurveyor.com

When the idea is better than the execution

Well, being a vintage watch enthusiast I would not mind winding my Seiko 8T23 even for five minutes, I guess… Once every few weeks. But in a time when millions of people nearly forgot what winding a watch means, I guess it wasn’t the hottest marketing sales point. Sadly, even the LED at the 6 o’clock that was ready to signal with a flash that the capacitor is not hungry anymore did not help.

Big crown. Big like.

Do you think of onions and pilots if somebody asks you about big crown watches? From now on you won‘t. Just one look at this Seiko 8T23 is enough to make sure you’ll never be able to un-see its crown. We already know that the watch developers were aware of the long winding procedure. At least with this crown, they wanted to make it less of a hassle, it is big, fat and nicely textured. With no fancy shape, it looks like a big wide runway ready for your fingertips to land and roll over it.

Image source: www.distinctivepurveyor.com

Elegant or sporty?

The Seiko 8T23 with a Full Charge Signal title on the dial was available in two different variations. The model with the code SBAD001 had lume plots and no numbers at the hour indexes, while the second model coded SBAD003 was sportier and came with a minute track at the hourly indexes. It might only be me, but looking at the other models sitting in the catalog next to it, the 8T23 is a definite winner.

Image source: Anthony Cable, www.plus9time.com

By the way, due to its shape, proportions and clean dial, it reminds me a bit of the Porsche Design IWC. The sportier SBD003 has a red minute track and Seiko logo, both feature a day/date aperture at three and a full-charge diode at 6. Both are cased in 35mm diameter and strapped with a stitched grey leather strap featuring a signed buckle. Both models were sold for ¥28,000 at that time, ¥3,000 more than Seiko asked for the Voice Note M516-4009.

Seiko 8T23 explained. A bit.

The innovative Seiko 8T23 movement looked on one hand like a traditional quartz watch and as a power plant on the other. To better understand the technicality behind it, I will help myself with a quote by Anthony Kable: ‘When the crown is turned, the rotational force is amplified via the power train and transmitted to the generator where AC power is created. The AC power is then rectified by a rectifier circuit to charge the capacitor. This capacitor is used as a power source to supply an IC that detects the voltage available and the charging process. Once the capacitor has been fully charged the overcharge prevention circuit is engaged and the charged LED is activated.’ If you’re interested in more technical details, I suggest you take a look at Anthony’s detailed article.

Image source: Anthony Cable, www.plus9time.com

End-of-Life Battery Indicator

When the watch begins to run low on power, it will start to move the second hand in two-second increments (many ETA quartz movements with this feature have a 5 seconds interval). If the user winds the watch and stops as soon as the second-hand returns to normal operation, the watch will last for approximately 30 hours of operation. If you want to have a more realistic video feel, I offer you this video I found on Instagram.

Image source: Anthony Cable, www.plus9time.com

Happy sad end

As this first manually wound quartz movement was produced for barely a year, it makes my eyes well up. But understanding that this technology was a warmup round for Seiko’s subsequent development of the A.G.S. or Automatic Generating System (later on, in 1991, it was branded Kinetic), there is a need to reach for a handkerchief. Design-wise and technology-wise I consider this gem to be a little miracle. It’s not only the first but probably also the only manually wound quartz movement. Therefore, I hope I find one soon and re-home it into my collection of watch oddities.

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About the author

Tomas Rosputinsky

During the day time, Tomas is an entrepreneur in the advertising, automotive and IT software industries. At night he turns into a watch enthusiast searching for quirky movements or vintage pieces with strong stories behind. Tomas was born and bred… read more

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