Seiko Thermic SBET001: The World’s First Thermoelectric Watch

Introduced in 1998, Seiko Thermic SBET001 is the world’s first thermoelectric watch powered by the body temperature of the wearer.

For the first time in the world, Seiko Co., Ltd. and Seiko Instruments Inc. succeeded in putting a power generation system for watches using human heat energy into practical use. The Seiko Thermic watch houses this power generation system. Commercially launched on 15th December 1998, it had a retail price of 300,000 yen (excluding tax).

Seiko Thermic Watch SBET001

When attached to the arm, Seiko Thermic SBET001 generates electricity based on the temperature difference between the body temperature of the arm and the outside air temperature, and operates while storing the electrical energy in the secondary power source. It is a watch that does not require battery replacement. By comprehensively designing the heat absorption and heat dissipation performance of the watch case and the movement, power is generated just by wearing it on the wrist.

Power save mechanism

This system minimizes wasted energy consumption when the wristwatch is not in use. When you put it on your arm and start power generation, the second hand starts to move, and when you remove it from your arm and power generation stops, the second hand stops at the position where the remaining battery level is displayed. The hour and minute hands are moving normally and can be used as a two-hand clock.

Furthermore, if power is not generated for about 3 days after the second hand stops (it is judged that it is not attached to the wrist), the minute and hour hands will move to the 12 o’clock position and stop. However, the electronic circuit in the watch keeps counting the time, and when power generation starts again, the stopped second hand, minute hand, and hour hand are in the original positions. The time is calculated and each hand moves separately in the shortest distance, indicating the current time instantly.

Perpetual calendar mechanism

The Seiko Thermic SBET001 watch has a perpetual calendar mechanism that does not require  correction until 2100. Also, when traveling abroad, you can press the button to adjust the time difference from the departure point to plus or minus with just the hour hand. During this time, the watch will not stop. Also, even if the time is corrected beyond the International Date Line, the calendar will change in tandem, so there is no need to correct it again.

Battery level indicator

The most disturbing thing about a watch with a built-in power generation system is how much battery power is left. A battery level indicator solves the problem of not knowing when to stop. It is displayed by pressing and holding the button at 2 o’clock for 2 seconds. The indicator has 4 levels and is displayed at the stop position of the second hand.

0 second position ~ About 2 weeks
10 seconds position ~ About 4 months
20 seconds position ~ About 8 months
30 seconds position ~ About 10 months

This timepiece houses the Seiko 6C12 caliber. Winner of the G-mark good design award in 1999, the Seiko Thermic SBET001 watch was a limited edition of 500 pieces.

Technical details

Model: SEIKO THERMIC Reference SBET001

Seiko 6C12 caliber
Time accuracy: Average monthly difference ± 15 seconds
Sustaining power supply when not carrying: Approximately 10 months (from full charge)
Waterproof performance: Waterproof for everyday life

Additional functions
Perpetual calendar function (no need to modify the calendar until the end of February 2100)
Calendar interlocking time difference correction function
Power save function Two-stage power saving method
Battery indicator function

Case: Three-layer insulation structure of upper torso (stainless steel), lower torso (glass fiber reinforced polyarylate), and stainless steel case-back
Diameter: 42mm
Bezel: Stainless steel
Glass: sapphire glass

Natural leather