SEIKO Thermic

The world's first watch that driven by body heat


Wayne Lee

I have been looking for a used Seiko Thermic (SBET001) for a long time.  When the watch was first introduced in December 1998, I remembered I could not afford one (neither could I afford one now, if I were to purchase a new one at the original retail price of 300,000 Yen).  As it was produced in limited numbers (500 pieces only) at that time, this model was quickly sold off within the first 3 - 4 months of its production. 

About 6 weeks back, while I was spending my research leave at Kyoto University, Japan, I found out that my friend, Marc Georgin (from USA) wanted to sell his Thermic.  I was so happy that I quickly contacted him.  After agreeing on the selling price, I asked Marc if he could wait and hold the watch for me, until I returned back to Malaysia to send him the payment and he kindly consented.

I received the watch yesterday evening and you could imagine how happy I am.   It is a gorgeous watch.  I think Marc has taken a very good care of the watch and he probably did not wear the watch too much either because it looked so mint as if it has not been worn.  My first real sighting of the watch was when I visited Seiko Institute of Horology during my recent trip to Japan.  This is not a small watch for small wrist of mine, but the futuristic design really attracted me.  All this while, I have been a GS collector who has been more inclined to classical Seiko designs (eg. Grand Seiko, King Seiko, etc).  Could it have been the technological marvel that attracted me?  Or the strange looking lugs that had pinched my attention? Or is it so-called a 'sustainable' watch product that has made me fallen into that recycling pit?

What is so special about this watch, other than its rarity?  Afterall, as most of you would put it - it is a quartz !.  Most quartz watches are powered by miniature batteries, but this watch is powered by converting body temperature into electricity.  Once it is fully charged, it will work for about 10 months without the need for power generation.  Based on my limited experience with the watch, I would call it as a hybrid which combined auto-relay technology and perpetual calendar with the new way of generating electricity through body temperature.  It has a perpetual calendar function that will automatically adjust for odd and even months, including leap years until February 28, 2100.  In addition, it has a power-saving mechanism that stops the display of the watch when no power is being generated to reduce power consumption (and so it will go to sleep while retaining the time in its memory).  In addition, upon going to another timezone, the time can also be adjusted in one-hour units without stopping the watch and the date will change automatically according to the set time. 

Power Generation Mechanism (quoted from the manual with additional information)

It has been known since 19th century that electricity can be generated through temperature differences.  It was first discovered in 1821 by a physicist Thomas Johann Seebeck.  Seiko Thermic is the first practical application of the so-called Seebeck effect in a watch.  When it is worn on the wrist, the watch absorbs body heat from the back case and dissipates it from the front of the watch to generate power with its thermal converter.  The power generating capacity depends on the air temperature and individual differences in body temperature.  As the difference between the air temperature and the surface temperature increases, the power generation performance increases.  As the difference decreases, the power generation performance will also decrease.  If the air temperature is equal to, or greater than the surface temperature, the watch is unable to generate power.  Here is a link to a technical site about the technology:  Thermoelectric Wristwatch

Living in the tropical Malaysia with warm temperature of 30 - 32oC throughout the year may pose a power generation problem to me if I were to wear the watch outdoor all the time.  Thank God - I spend almost 10 hours daily in my office and laboratory which are air-conditioned at 20oC.  However, to be frank, I would not recommend anyone from the tropics who work outdoor most of the time to purchase the watch.  This afternoon when I got inside my 'oven hot' car which had been exposed to the sun for several hours (I could not find a parking space under the shade this morning), the second hand stopped ticking.  I was panic and quickly get back home to check the manual.   After checking the manual, I found out that when the ambience temperature is higher than that of the wrist, it will stop generating power and the second hand will stop at 4 o'clock as shown above. 

The watch - how I feel

The watch is large (42 x 54 mm case) and comes along with a very detailed manual which explains every single feature of the watch, its proper usage, product descriptions, and ways to preserve the quality of the watch, trouble-shooting, after sales servicing and specifications.  The strap is made from soft plastics (not leather), thus it does not require special care.  It can be rinsed with soapy watch if needed.  The feeling of the strap is very similar to the the original Seiko Military 4S15 automatic's synthetic strap.  The watch box is huge and truly made with pride that matches those of the high-end Swiss watches.  I am very lucky to be able to own the limited edition numbered 25/500.  I must thank Marc again for providing me this opportunity to own this watch.  Before the watch was sold to me, Marc had also sent the watch to Seiko Japan for service and fine-tuning.  This is clearly reflected on the warranty card that came along.  The buckle of the watch looks futuristic with the matte curve and grooves.  The watch is very comfortable on the wrist..  The weight is optimal and I do not feel the bulkiness of what I had experienced earlier with heavy watches (eg. Seiko Marine Master automatic).   The red second hand matches perfectly with the black dial and ticking sharp on the center of each index. Each tick does not carry any sound - just like my Grand Seiko quartz. 


Specifications of the watch (based on the manual)

Movement - Thermic 6C12.

Water resistant - up to 30 m only (withstand accidental contact with water such as splashed and rain).

Crystal oscillator frequency - 32,768 Hz (cycles per second).

Loss/gain (monthly rate) - Less than 15 seconds at normal temperature range (5 - 35oC) (when wearing the watch).

Operational temperature range -  -10 to +60oC.

Driving system - stepping motor, 4 pieces. 

Display system - Time display (hour, minute, second and date [second: battery indicator]), calendar display (month, date [fully automatic calendar until February 28, 2100), hour and minute; time difference adjustment (+/- 23 hours [date] and hour).

Battery - second lithium ion battery.

Retention time - From full charging to stop (about 10 months).

Other functions - remaining energy level warning; power saving function; charging level display function (indicator).

Electronic circuit - dedicated microcomputer; recharging control circuit [2 C-MOS-LSIs].

Power generator - Thermal conversion element.

In conclusion, the Seiko Thermic is a 'must-have' to those watch collectors whom possessed a deep passion for marvel technology.  The watch is most suitable for usage by those living in temperate countries.  It remained unknown though at this stage whether there will be problems associated with power-keeping capability like those experienced with the earlier calibers of Seiko Kinetics (i.e. capacitor problem) after the watch is being used for more than 5 years.  Only TIME  will tell.  Nevertheless, this is a wonderful technology that I believe will be further exploited in future.   Here is another writeup about the technology:  Body heat


Wayne Lee (March 29, 2003), Penang Island, Malaysia.