Seiko Caliber H855 Watch Movement

Manufacturer	Seiko Instruments Inc.
Caliber Number	H855
Movement Type	Quartz, solar-powered
Display Style	Analog with digital field effect screen (ana-digi)
Jewel Count	0
Frequency	32,768 Hz
Battery/Capacitor	Unconfirmed
Power Reserve	5 months on full charge
Accuracy Rating	+/- 15 seconds/month
Hand Count	3
Functions	Central hours; central minutes; central seconds; digital display at 6:00 (depth measuring up to 80m, diver’s log up to 100 dives, chronograph, alarm, perpetual calendar good until 12/31/2100, low battery warning), LED internal light
Electronic Circuits	C-MOS integrated circuit (oscillation, division, drive, and LED); pressure sensors
Hacking Seconds?	Yes
Country of Manufacture	Made in China (as per caseback text)
Known Models	Seiko Propsex Hybrid Diver (Ref: SNJ033P1), Seiko Prospex “Arnie” Hybrid Diver 40th Anniversary (Ref: SNJ037P1 limited edition to 4,000 pieces), Seiko Prospex Solar Analog-Digital Diver (Ref: SNJ035P1) (Add your watch to the comments below…)

Seiko caliber H855 is a solar-powered quartz ani-digi watch movement. Timepieces with this caliber were announced in June 2022.

In Seiko’s own words:

“Celebrating the partnership between Seiko Prospex and PADI, the world’s leading scuba diver training organization, this Special Edition features the new H855 caliber movement, commemorating the 40th anniversary of the H558-5000, introduced in 1982 as the world’s first analog-digital hydrid diver’s watch with an alarm and chronograph.” –Source

Power Reserve Expectations:

When the rechargeable battery (often called a capacitor in the watch world) is fully charge via a light source such as the sun, you can expect somewhere between 5 and 6 months of power reserve (even Seiko doesn’t seem to be sure).

On Seiko’s product page for the Prospex Solar Analog-Digital Diver, they state:

“The energy-efficient solar cell, powered by any light source, with no battery change required, provides a 6-month power reserve when fully charged.” –Source

As well as:

“5-month power reserve once fully charged.”

But then there’s another product page stating this:

“Power reserve: Operating for approx. 19 months (when fully charged)” –Source

H855 VS H851:

There is a similar caliber H851 which has the digital screen at 12:00 instead of 6:00. The functionality is similar with exception to the advanced diving features on the H855.

Fratello Magazine covers the specific differences in their review:

“The H855 adds depth measuring to 80 meters into the mix. It is also equipped with a diving log that can record the dive time and depth of up to 100 dives. When in diving mode, the log automatically starts when you descend past 1.6 meters. As you ascend to less than 1.5 meters, the log ends your dive and automatically stores the data. These Seiko Hybrid divers even warn you when a rapid ascent is detected. Is Seiko trying to bridge the gap between divers’ watches and diving computers?”