By the mid 80’s the quartz revolution had successfully dominated the watch industry. This resulted in large numbers of watches being sold, but with the rapid technological developments the prices of watches fell very rapidly resulting in the perception that these were now commodity items. The high numbers of quartz watches also resulted in massive numbers of batteries being produced and disposed of each year. The environmental impact of these batteries was identified as an issue that would continue to grow so Seiko decided to develop a product that would not require continued battery replacement.

To meet this criteria Seiko Instruments Inc. (SII) developed the 8T23 caliber. This was the world’s first hand wound quartz watch. 

The wearer is able to wind the crown to turn a small electrical generator that charges a capacitor. The quartz movement is then able to be powered from the capacitor. As the capacitor is able to be recharged continually the watch does not need to have batteries replaced regularly. 

To develop the movement a couple of key technological hurdles had to be overcome. Firstly a compact power generation system that could fit inside a watch needed to be created. 

Once it was decided that the watch would be powered by the user themselves by winding the watch it was fitted with a distinctive oversized crown that makes this regular operation easier. Unlike a mechanical watch the crown is able to generate power if wound clockwise or anti-clockwise as the generator will produce an AC signal. The designers specified the target of a three minute winding time to go from completely discharged to a full capacitor. Once the watch is fully charged the red LED at the 6 o’clock position is lit to indicate to the user that further winding is not required.

A full charge on the capacitor will provide approximately 75 hours power reserve.

The 8T23 hand wound movement was only produced for a little over a year. I think that a three minute winding operation for a three day power reserve is not something that many customers would find acceptable. In the following year (1988) the Seiko Epson produced AGS (automatic generating system) technology, later to be renamed Kinetic, was released. This design did not require manual winding and instead used a weighted rotor to move the generator in the same way an automatic mechanism generates power. The ability to hand wind a Kinetic movement was added with the introduction of the Kinetic Direct Drive technology almost twenty years later in 2007.

While not commercially successful the 8T23 is an interesting movement and very likely the solitary hand wound only quartz model ever produced.