What is a solar-powered watch? A detailed explanation of its mechanism and features
A solar-powered watch (solar watch) is a quartz wristwatch that converts light that hits the dial into electrical energy and stores it in a built-in secondary battery (rechargeable battery).
If used in a light-filled environment on a daily basis, the watch will continue to charge, so unlike a typical battery-powered quartz watch, it does not necessarily require periodic battery replacement.
Its appeal is its low maintenance and practicality.
Nowadays, many brands, including Citizen and Seiko, use this feature as a core feature, and it is gaining popularity as an everyday watch.
How solar batteries work
The mechanism is very simple.
When light from sunlight or indoor lighting hits a solar cell, electrons move within the semiconductor, generating electricity, a phenomenon known as the "photovoltaic effect."
Solar watches use this mechanism to generate electricity.
Flow from power generation to drive
Light coming through the glass surface hits the dial
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Light passes through the dial and reaches the solar cell underneath.
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Solar cells convert light into electrical energy
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Storing electricity in a secondary battery
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Stored power powers the quartz movement
This is how light energy is converted into power.
Solar watch dial structure
The dial of a solar watch has a special structure that combines design with power generation efficiency.
A thin solar cell is placed directly below the dial, and is designed so that the solar cell is not visible.
It uses a special material that appears opaque at first glance but allows light to pass through.
Materials include special plastics and resins, and depending on the model, traditional materials such as washi paper may also be used.
Although it looks almost the same as a regular watch, its main feature is that it efficiently generates electricity internally.
The difference between primary and secondary batteries
There are two main types of batteries used in watches.
■ Primary batteries (disposable)
This is the case with the button battery found in a typical quartz watch.
Lifespan: Approximately 2-3 years
Not rechargeable
Replace the battery when it runs out
Although it is inexpensive and stable, it requires periodic replacement.
■ Secondary battery (rechargeable)
This is the battery used in solar watches.
Lifespan: Approximately 7 to 10 years (varies depending on usage)
Can be repeatedly charged and discharged
Battery replacement is less frequent
However, this is not permanent, and the capacity will gradually decrease over time due to long-term use or exposure to high temperatures.
Secondary battery life and signs
Generally, the lifespan of a secondary battery is approximately 7 years.
It is said that performance gradually declines after about 3,000 to 3,500 charge/discharge cycles.
If you experience any of the following symptoms, you should be careful.
It stops working immediately even after being fully charged
The second hand moves every 2 seconds and 4 seconds
Difficult to recover even after charging
First, try charging it in sufficient light. If this does not improve the situation, it may be time to have it inspected or have the secondary battery replaced.
Solar cell characteristics
Many solar-powered watches use amorphous silicon semiconductors, which are thin, lightweight, and resistant to indoor light.
Therefore, it can be charged not only by sunlight but also by light from fluorescent lamps and other sources.
Many models can run for several months on a full charge, making them very easy to use watches for everyday use.
What to do when your solar watch battery runs out
If your solar-powered watch stops, don't immediately assume it's broken. In most cases, the cause is insufficient charging. Follow the steps below to check.
① First, fully charge it
Solar-powered watches can be charged not only by sunlight but also by indoor lighting.
If possible, place it in a sunny window for a few hours.
The ideal position is with the dial facing up and the light hitting it directly, not through the glass.
Avoid leaving the device in direct sunlight for long periods of time in summer (high temperatures can cause malfunctions).
If the battery is completely stopped, it may need to be charged for several hours to half a day.
*If only the interior lights are on, it may take some time for the power to recover.
② Check the movement of the second hand
Many solar-powered watches have a low-charge warning function.
The second hand moves every two seconds
Moves every 4 seconds
This behavior is a sign that the watch is not fully charged. It will return to normal behavior once fully charged.
③ If it still stops
Even if it is fully charged,
Stops immediately
Does not return from power save
Charging does not improve the situation
If you experience any of the following symptoms, the secondary battery may be deteriorating.
The secondary battery in a solar watch generally has a lifespan of around seven years. If you have been using it for many years, it may be time to replace or inspect the battery.
④ Go to a specialist store for secondary battery replacement
Replacing the battery in a solar watch is different from replacing a regular button battery.
Uses a dedicated secondary battery
Waterproofing needs to be rechecked
Specialized work required to avoid strain on the movement
Therefore, it is safe to have it replaced at an authorized service center or specialist shop.
summary
The basic steps to take if your solar watch stops are:
First, charge with sufficient light
Check the movement of the second hand
If there is no improvement, request an inspection
In most cases, this is caused by insufficient charging, but if you have been using the device for many years, it may also be due to the end of the life of the secondary battery.
Solar watches can be used comfortably for a long time if they are properly charged and inspected regularly.
CONTÉVANOU is an authorized dealer of watches and jewelry in the Nishi-sando area of Shibuya Ward, Tokyo. From watches with unique designs to high-quality jewelry, you can take your time to look at the actual items in your hands.
CONTÉVANOU, authorized watch and jewelry dealer
Nishi-sando Terrace E1, 28-7 Yoyogi 4-chome, Shibuya-ku, Tokyo
TEL: 03-3299-8008