When your watch suddenly stops ticking, your thermometer won’t switch on, or your calculator gives up mid-use, the problem is often as simple as a drained battery. Many compact devices rely on a specific coin-cell power source: the SR626SW battery.
This small yet dependable battery is designed to deliver steady performance in precision electronics where reliability is paramount.
In this guide, we’ll take a closer look at what the SR626SW battery is, its technical details, and how it compares with alkaline alternatives.
We’ll also walk through the different SR626SW battery equivalent, such as the 377 and AG4, and share practical tips on choosing the right replacement, handling it safely, and disposing of it responsibly.
What is the SR626SW Battery?
The SR626SW is a compact silver-oxide button cell battery, measuring about 6.8 mm in diameter and 2.6 mm in height.
It operates at 1.55 volts and is non-rechargeable, but what makes it stand out is its ability to deliver a steady, reliable voltage over its entire lifespan.
With a typical capacity of around 25–27 mAh, it’s built to power small devices consistently and for longer periods than many of its alkaline counterparts.
Often referred to simply by its size code “626,” this cell is one of the most widely used silver-oxide watch batteries on the market. You can also source it directly in bulk SR626SW packs for long-term use.
The “SW” in SR626SW stands for Silver Oxide, Watch Standard, which means it complies with the IEC 60086-3 standard specifically for watch batteries.
In practice, you’ll find SR626SW batteries in a wide range of analog watches, calculators, small digital gadgets, laser pointers, electronic toys, and even certain medical instruments.
Origin of the “SR626SW” Naming Convention
Battery names give clues to its chemistry and size. “SR626SW” is an industry designation based on standards set by the International Electrotechnical Commission (IEC).
Here’s the breakdown:
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SR626SW Battery Technical Specifications
Before choosing the right replacement, it’s important to understand the technical foundation of the SR626SW battery. These specifications are what make it a trusted choice for watches, calculators, medical instruments, and other compact electronics.
By looking at its chemistry, size, and performance behavior, you can see why manufacturers and repair professionals continue to recommend this coin cell for precision devices.
Chemistry and Voltage
The SR626SW battery uses silver-oxide chemistry, engineered to provide a nominal voltage of 1.55 V.
Its key advantage is a stable voltage output that stays consistent for most of the battery’s service life. This ensures accurate operation in sensitive devices such as watches and medical instruments.
Capacity and Longevity
With a typical capacity of 25–27 mAh, the SR626SW delivers reliable runtime for low-drain applications while offering a shelf life of 5–7 years or more.
It also has a very low self-discharge rate of approximately 2% annually under room-temperature storage. This makes it a dependable choice not only for immediate use but also as a backup battery stored for later use.
Size and Standardization
Following IEC and ANSI standards, the SR626SW measures 6.8 mm in diameter and 2.6 mm in height, with a typical weight of 0.39–0.40 g.
It is universally recognized across different naming codes, including SR66 (IEC) and 1176SO (ANSI), which ensures consistent compatibility in devices designed for this form factor.
Operating Conditions
The SR626SW operates reliably in temperatures from −10 °C to +60 °C which makes it suitable for a variety of environments.
It is typically rated for a standard discharge current of ~40 µA under a 24 kΩ load at 23 °C. This range reflects the low-power requirements of most watch and medical device applications.
Fresh cells also exhibit low internal resistance (≤ 8 Ω), supporting stable operation in both low- and moderate-drain conditions.
High-Drain and Low-Drain Applications
Modern SR626SW cells are manufactured as multi-drain batteries, meaning they can efficiently support both high-drain features (like alarms or backlights) and low-drain requirements (such as analog watch movements).
This versatility eliminates the need to choose between older 376 (high drain) and 377 (low drain) variants, simplifying replacement.
| Attribute | Specification |
|---|---|
| Chemistry | Silver Oxide (Ag₂O) |
| Nominal Voltage | 1.55 V (stable output until ~1.2 V cutoff) |
| Capacity | ~25–27 mAh |
| Dimensions | Ø 6.8 mm × 2.6 mm |
| Shelf Life | Typically 5–7 years (when stored under proper conditions) |
| Performance | Maintains steady voltage for most of its life; supports both high- and low-drain use |
| Designation Codes | SR626SW (IEC), SR66, 1176SO (ANSI), 377/376 equivalents |
The SR626SW battery combines precision engineering with proven reliability, making it one of the most widely adopted coin cells in modern electronics. Its technical specifications ensure confidence that your devices will perform exactly as intended.
Case Study: SR626SW Battery vs LR626 Battery
Sometimes the interchangeable use of SR626SW and LR626 often leads to confusion, since both fit the same devices but differ in chemistry.
To illustrate the differences clearly, we reviewed two representative datasheets: one for a silver-oxide SR626SW (Renata 377) and another for an alkaline LR626 (generic manufacturer).
Let’s compare the key specifications:
| Attribute | SR626SW | LR626 | Observation |
| Chemistry | Silver Oxide (Ag₂O) | Alkaline Manganese | Different chemistry types |
| Nominal Voltage | 1.55 V | 1.5 V | Nearly identical at start, but SR626SW holds voltage steady |
| Voltage Profile | Stable until ~1.2 V cutoff | Declines steadily to ~1.0 V | Silver oxide provides consistent performance |
| Capacity (typical) | 25–27 mAh | 15–17 mAh | SR626SW lasts 30–50% longer |
| Operating Temp. | –10°C to +60°C | –10°C to +55°C | Broadly similar range |
| Shelf Life | 5–7 years | 2–3 years | Silver oxide offers better storage stability |
| Leakage Resistance | High | Moderate | Alkaline more prone to leakage |
| Dimensions | Ø 6.8 mm × 2.6 mm | Ø 6.8 mm × 2.6 mm | Exact physical match |
| Compliance | IEC 60086-3 “Watch Standard” | General-purpose | SR626SW designed for precision timekeeping |
Voltage Stability
SR626SW Datasheet
For SR626W, the discharge curve shows a flat and stable voltage profile at ~1.55 V for most of the battery’s life.
Only after delivering nearly 25–27 mAh does the voltage suddenly drop, reaching ~1.2 V before complete depletion.
This “plateau behavior” ensures devices like watches and medical instruments operate with consistent accuracy until the very end.
LR626 Datasheet
In contrast, the alkaline discharge curve shows a steady decline in voltage from the moment it begins discharging.
Starting at ~1.5 V, it gradually drops below 1.2 V around mid-life and approaches 1.0 V by ~50 hours of runtime.
This sloping curve means devices may lose accuracy or underperform well before the battery is fully drained.
Common Devices and Applications
The SR626SW battery has earned its popularity because it powers a wide variety of small electronic devices.
Its compact size, steady voltage, and reliable performance make it a popular across multiple applications. Below are the common devices and applications of SR626W battery:
Wrist Watches
Both analog and entry-level digital watches often rely on the SR626SW. Well-known brands like Casio, Timex, and Swatch design many of their quartz models around this cell, which is why it’s often referred to simply as a “watch battery.”
The “W” in the code even highlights that it complies with international watch standards. If your timepiece calls for a 377 or SR626SW battery, the Seiko Instruments SR626SW is a reliable replacement.
Calculators
Many pocket calculators, especially older or compact models, are designed to use coin cells in the 6.8 × 2.6 mm size range. While some run on larger types like LR44, a good number use the SR626SW or its equivalents for long-lasting performance.
Thermometers and Medical Devices
From digital fever thermometers to glucose meters, small medical gadgets often specify silver-oxide cells for their consistent output. The SR626SW battery is ideal here because accurate readings depend on stable voltage.
Unlike alkaline cells, which can drain quickly, silver-oxide chemistry ensures steady performance until the battery is nearly depleted.
Electronic Toys and Laser Pointers
Mini remote controls, laser pointers, LED keychain flashlights, and other compact toys frequently use this battery. These devices demand bursts of power in a small package.
In such cases, an alkaline LR626 equivalent may run out quickly, but a silver-oxide SR626SW will hold up better, especially in toys with lights or motors.
Key Fobs and Portable Gadgets
Although most modern car key fobs use larger lithium coin cells (like CR2032), some smaller remotes, pedometers, and stopwatches are built around the 626-size cell.
If you’re replacing a battery in a fitness gadget or compact remote, chances are high you’ll need the SR626SW or its equivalents.
In summary, the SR626SW battery provides reliable, long-lasting power in watches, calculators, medical devices, small toys, remotes, and other compact gadgets.
Tips for Choosing the Right Replacement
When it’s time to replace an SR626SW battery, a little attention to detail can save you from poor performance or short lifespan. The following guidelines outline best practices:
1 . Choose Silver Oxide Over Alkaline
Always opt for a silver-oxide cell (SR626SW or 377) instead of an alkaline version like LR626 or AG4. Silver oxide delivers a steadier voltage, lasts longer, and is less likely to cause issues in precision devices such as watches.
Check the packaging carefully, reputable brands will clearly label “Silver Oxide.” If it only says 377 or AG4, look at the fine print for the chemistry.
For watches and other sensitive devices, silver-oxide is the way to go.
2. Stick to Reputable Brands
Not all coin cells are created equal. Brands like Duracell, Energizer, Renata, Panasonic, Maxell, Sony/Murata, and Varta consistently provide quality and freshness.
For example, Renata 377 is trusted by many watchmakers, while Energizer 377/376 and Duracell D377/376 are reliable multi-drain options.
Choosing a known brand ensures the stated capacity, reduces leakage risks, and keeps your device running smoothly. For convenience, Flywing Tech provides genuine SR626SW batteries alongside other electronic components, ensuring verified quality.
3. Check Shelf Life
Look for the expiration date or “best before” mark on the packaging. Fresh batteries mean maximum capacity and a lower chance of leakage.
Silver-oxide cells typically have a shelf life of 5 years or more if stored correctly.
4. Consider Multi-Packs
For users managing multiple devices, multi-packs (e.g., 5 or 10 units) may offer cost efficiency. Unused batteries should be stored in original packaging in a cool, dry environment, and only opened when required.
5. High-Drain vs Low-Drain Options
Historically, manufacturers distinguished between 376 (high-drain) and 377 (low-drain) cells. Today, most reputable brands supply multi-drain SR626SW cells suitable for both applications. If choosing between the two:
- Devices with alarms, backlights, or higher current draw require high-drain (376).
- Simple analog watches are adequately supported by low-drain (377).
When uncertain, select a multi-drain model to ensure compatibility.
6. Verify Fitment
After installation, check that the battery fits snugly, the cover closes properly, and the device powers on.
While the SR626SW battery equivalent shares the same size, don’t confuse it with similar-looking cells like the SR621SW (6.8 × 2.1 mm). That 0.5 mm difference can prevent proper contact and cause malfunctions.
In short, by choosing silver-oxide chemistry, sticking with trusted brands, checking freshness, and matching the correct code, you’ll ensure your SR626SW replacement battery delivers the performance your device was designed for.
Final Thoughts
The SR626SW battery may be small, but it’s vital for keeping watches, calculators, thermometers, and other compact devices running reliably. Measuring 6.8 × 2.6 mm, this silver-oxide cell delivers a steady 1.55V output and dependable capacity, qualities that set it apart from its alkaline counterparts.
It’s also sold under various codes, including 377, 376, LR626, AG4, SR66, and others, but all refer to the same size. Knowing these SR626SW battery equivalents means you can confidently pick the right replacement even if the exact code isn’t available.
For best results, always choose a quality silver-oxide version from a reputable brand. This ensures longer life, stable performance, and reduced risk of leakage.
At Flywing Tech, we make it easier by offering authentic SR626SW watch batteries you can use.
Frequently Asked Questions (FAQs)
What is the SR626SW battery commonly used for?
The SR626SW battery is widely used in wristwatches, calculators, thermometers, medical devices, toys, and small electronics that require steady, reliable power in a compact size.
Is SR626SW battery the same as 377?
Yes. SR626SW and 377 are equivalent designations for the same silver-oxide coin cell battery. Manufacturers use different codes, but both refer to a 6.8 × 2.6 mm silver-oxide battery with a nominal voltage of 1.55 V.
Can I replace an SR626SW battery with an LR626?
Physically yes, since they are the same size. However, LR626 is alkaline and has a shorter life, less stable voltage, and a higher chance of leakage. For watches and precision devices, SR626SW (silver oxide) is strongly recommended.
How long does an SR626SW battery last?
In a typical quartz watch, an SR626SW can last 2–3 years. Runtime depends on the device’s power consumption and whether it has extra features like alarms or lights.
Are SR626SW batteries rechargeable?
No. SR626SW batteries are primary (non-rechargeable) silver-oxide cells. Attempting to recharge them is unsafe and can cause leakage or damage.
How should I dispose of an SR626SW battery?
Always recycle button cell batteries through local battery recycling programs. Do not throw them in household trash, as they contain chemicals that should be handled responsibly.
How do I know if I bought a genuine SR626SW battery?
Check the packaging for clear labeling (“SR626SW” or “377,” “Silver Oxide,” and “0% Mercury”) and purchase only from trusted retailers like Flywing Tech or authorized electronic suppliers to avoid counterfeit products.
Can the SR626SW battery be stored for long periods?
Yes. Silver-oxide cells typically have a shelf life of 5+ years when stored in a cool, dry place. Always check the expiration date on the packaging before use.
