Complete SR626SW Battery Guide with Equivalents and Specs

The SR626SW battery is one of the most widely used silver oxide button cells for precision electronic devices. Despite its small size, this battery plays a critical role in maintaining stable voltage for watches, medical instruments, calculators, and other compact electronics where accuracy is essential.

Because multiple international naming systems exist, buyers often encounter different model numbers such as 377, SG4, or SR66, making product selection confusing. Understanding the correct SR626SW battery equivalent, physical dimensions, chemistry, and handling practices helps engineers, procurement teams, and maintenance professionals avoid compatibility issues and ensure long-term device reliability.

This guide explains everything you need to know about the coin battery SR626SW, from specifications and replacement options to counterfeit detection, storage recommendations, and sourcing strategies.

What Is the SR626SW Battery

SR626SW is a 1.55V silver oxide button cell commonly used in low-drain precision devices, according to manufacturer technical data for SR626SW / 377 cells. Unlike alkaline button cells, silver oxide chemistry maintains an exceptionally stable output voltage throughout most of its service life.

Key characteristics include:

Specification	Value
Chemistry	Silver Oxide (Zn/Ag2O)
Nominal Voltage	1.55V
Shape	Coin/Button Cell
IEC Designation	SR626SW
Typical Capacity	25–28 mAh
Drain Type	Low Drain

Values may vary slightly by manufacturer; data referenced from Maxell SR626SW and Renata 377 technical documentation.

The suffix "SW" stands for Silver Low Drain, indicating that the battery is optimized for devices requiring consistent current over extended periods rather than high pulse discharge.

From a component distribution perspective, silver oxide chemistry remains the preferred choice whenever stable voltage directly affects circuit accuracy. Precision quartz watch oscillators, analog measuring devices, and miniature medical electronics all benefit from the flat discharge profile offered by the coin battery SR626SW.

Exact Dimensions of the SR626SW Coin Battery

Although many button cells appear visually similar, dimensional tolerances are critical during hardware development and manufacturing.

The standard physical specifications are:

Parameter	Measurement
Diameter	6.8 mm
Height	2.6 mm
Weight	Approx. 0.3 g
Shape	Coin Cell

These standardized dimensions ensure compatibility with battery holders designed according to IEC specifications.

For hardware engineers, battery size directly influences:

• PCB mechanical layout
• Battery holder selection
• Injection mold design
• Waterproof sealing
• Electrical contact reliability

Even slight dimensional deviations can lead to intermittent electrical contact or assembly failures in high-volume production. Therefore, verifying battery dimensions during component qualification is an essential step in product development.

Top SR626SW Battery Equivalents and Replacements

One of the most common questions engineers ask is:

What is the correct SR626SW battery equivalent?

Fortunately, several manufacturers use different naming conventions while producing electrically compatible batteries.

SR626SW Battery Cross-reference Table

IEC Model	Common Name	Brand Equivalents	Chemistry	Voltage	Typical Capacity	Dimensions	Interchangeable
SR626SW	377	Maxell, Sony, Panasonic, TDG	Silver Oxide	1.55V	25–28 mAh	6.8 × 2.6 mm	Yes
SR626SW	SG4	Seiko, Citizen	Silver Oxide	1.55V	25–27 mAh	6.8 × 2.6 mm	Yes
SR626SW	377A	Renata, Energizer	Silver Oxide	1.55V	26–28 mAh	6.8 × 2.6 mm	Yes
SR626SW	D377	Duracell	Silver Oxide	1.55V	25–27 mAh	6.8 × 2.6 mm	Yes
SR626SW	SR66	Varta, Philips	Silver Oxide	1.55V	25–28 mAh	6.8 × 2.6 mm	Yes
SR626SW	377S	Toshiba, Hitachi	Silver Oxide	1.55V	25–27 mAh	6.8 × 2.6 mm	Yes
SR626SW	SR626	Matsushita, Panasonic	Silver Oxide	1.55V	25–28 mAh	6.8 × 2.6 mm	Yes
LR626 / LR66	AG4	Various Alkaline Brands	Alkaline	1.5V	18–22 mAh	6.8 × 2.6 mm	Physically compatible, but not ideal for precision devices

Selection Considerations

When selecting an SR626SW battery equivalent, engineers should verify:

• Battery chemistry
• Nominal voltage
• Physical dimensions
• Continuous discharge characteristics
• Manufacturer quality standards

Equivalent part numbers simplify BOM management and provide flexibility when original components experience supply shortages.

Silver Oxide VS Alkaline Button Cells

Although some online replacement charts list AG4 as an alternative, engineers generally discourage replacing a silver oxide battery with an alkaline button cell.

The primary differences include:

Feature	Silver Oxide (SR626SW)	Alkaline (AG4/LR626)
Voltage	1.55V Stable	Starts at 1.5V then drops quickly
Discharge Curve	Flat	Steep
Service Life	Longer	Shorter
Leakage Risk	Low	Higher
Precision Electronics	Excellent	Not Recommended

Why Voltage Stability Matters

Quartz watches, medical sensors, and precision timing circuits rely on consistent operating voltage.

Silver oxide batteries maintain nearly constant voltage until almost completely discharged.

Alkaline cells gradually lose voltage from the beginning of their discharge cycle, potentially causing:

• Slow watch movement
• Sensor inaccuracies
• Reduced measurement precision
• Unexpected shutdowns

Leakage Concerns

Lower-cost alkaline batteries also carry a greater long-term leakage risk.

Electrolyte leakage can permanently damage:

• Battery contacts
• PCB traces
• Metal springs
• Plastic battery compartments

For high-value electronic products, the small cost savings rarely justify the potential maintenance expense.

Common Applications for the SR626SW

Because of its stable electrical characteristics, the SR626SW battery serves numerous precision electronic products.

Typical applications include:

Industry	Typical Products
Watch Manufacturing	Quartz watches
Medical Devices	Glucose meters
Consumer Electronics	Pocket calculators
Optical Equipment	Laser pointers
Industrial Instruments	Digital gauges
Portable Sensors	Temperature sensors
Test Equipment	Miniature measuring devices

The battery is especially valued wherever oscillator frequency stability depends upon a consistent supply voltage.

Its compact size also makes it suitable for wearable electronics where both space and reliability are critical.

Identifying Counterfeit Batteries in Bulk Orders

Counterfeit batteries remain a growing concern within the global electronics supply chain.

Experienced independent distributors recommend multiple verification steps before accepting bulk shipments.

1. Verify Batch Codes

Authentic manufacturers use traceable production lot numbers that correspond to manufacturing records.

Missing or inconsistent batch markings should raise immediate concern.

2. Examine Packaging

Look for:

• High-resolution printing
• Correct manufacturer logos
• Clear expiration dates
• Proper holographic labels
• Factory sealing integrity

Poor print quality often indicates unauthorized production.

3. Measure Open Circuit Voltage (OCV)

Incoming quality inspection should include random sampling.

Typical acceptance criteria:

Parameter	Standard
Nominal Voltage	1.55V
Acceptable OCV	1.58V–1.62V

Values significantly below specification may indicate aged inventory or counterfeit products.

4. Inspect Surface Finish

Authentic silver oxide batteries typically exhibit:

• Uniform stainless-steel finish
• Clean laser markings
• No corrosion
• No dents
• Consistent crimp quality

Mechanical inconsistencies frequently indicate substandard manufacturing.

Optimal Storage Conditions to Minimize Self-Discharge

Even premium silver oxide batteries experience gradual self-discharge during storage.

Proper inventory management significantly extends shelf life.

Recommended storage conditions include:

Condition	Recommendation
Temperature	10–25°C
Relative Humidity	35–65% RH
Packaging	Anti-static insulated packaging
Sunlight	Avoid direct exposure
Metal Contact	Prevent short circuits

FIFO Inventory Management

Independent distributors typically implement First-In, First-Out (FIFO) inventory control to reduce long-term storage risks.

FIFO ensures older inventory ships before newer stock, minimizing capacity loss caused by prolonged warehouse storage.

Proper warehouse management also includes:

• Moisture control
• Static protection
• Lot traceability
• Shelf-life monitoring

Reliable Global Sourcing for SR626SW Batteries

Global electronics manufacturers continue facing periodic supply disruptions caused by fluctuating raw material costs, transportation delays, and changing production schedules.

Maintaining supply chain resilience requires:

• Multiple qualified manufacturers
• Cross-brand qualification
• Inventory forecasting
• Alternate BOM approval
• Component authenticity verification

Working with experienced independent distributors allows procurement teams to respond more effectively when original factory lead times increase unexpectedly.

Expert Tips for Handling and Installation

Proper installation practices help maximize battery life and protect sensitive electronics.

Recommended handling practices include avoiding short circuits, confirming polarity, and keeping contacts clean during assembly.:

Use Insulated Tweezers

Never install button cells using bare metal tools.

Insulated tweezers prevent accidental short circuits during assembly.

Wear Anti-Static Finger Cots

Human skin contains moisture, salts, and oils that may accelerate contact corrosion.

ESD-safe finger cots reduce contamination while protecting electrostatic-sensitive components.

Observe Correct Polarity

Always verify:

• Positive terminal orientation
• Battery holder markings
• Device documentation

Incorrect installation may damage sensitive circuits.

Avoid Excessive Pressure

Button cells should fit naturally within battery holders.

Excessive force can deform contacts or damage battery sealing

Keep Contacts Clean

Dust, fingerprints, and oxidation increase contact resistance.

Before final assembly, inspect battery terminals for cleanliness and proper alignment.

Technical references

• Manufacturer datasheets: Maxell SR626SW; Renata 377 technical data sheet。
• Manufacturer reference guide: Maxell Micro Battery Cross Reference and Replacement Guide。
• Industry standard framework: IEC 60086 series, as referenced in VARTA conformity documentation for silver oxide button cells。
• Authorized distributor references: Mouser, Farnell, DigiKey product technical pages for model cross-checking。