SR626SW Battery Equivalent: 377, AG4, LR626 and Watch Replacement Guide

SR626SW is a small silver oxide button cell commonly used in analog watches and other low-drain electronic devices. Its most common replacement code is 377, but equivalent selection should not be based on the printed code alone. Size, voltage, chemistry, discharge behavior, and the device's current requirement all affect whether a replacement battery will work reliably.

The common search terms around this battery include SR626SW battery, SR626SW equivalent, 377 battery, SR626SW 377 equivalent, watch battery SR626SW replacement, AG4 replacement, and LR626 equivalent. These terms often point to batteries with similar physical size, but not always the same chemistry or discharge performance.

For most analog watches, a silver oxide 377 or SR626SW is the preferred replacement. Alkaline cells such as AG4 or LR626 may fit into the same compartment, but they are not always the best choice for watches because their voltage is less stable as they discharge.

SR626SW Battery Specifications

SR626SW is a silver oxide watch battery with a nominal voltage of 1.55V and a size close to 6.8mm diameter by 2.6mm height. The "SR" prefix indicates silver oxide chemistry, while the "626" size code refers to the approximate diameter and height class of the button cell.

Renata lists its 377 battery with 1.55V nominal voltage, 6.8mm diameter, 2.6mm height, and cross-references including SR626SW, SR66, V377, D377 and other brand markings. (Renata, 377 Silver Oxide Battery Technical Data)

Specification	SR626SW / 377 Battery
Battery chemistry	Silver oxide
Nominal voltage	1.55V
Approximate diameter	6.8mm
Approximate height	2.6mm
Common equivalent	377 battery
Typical application	Analog watches and low-drain miniature electronics

The important point is that SR626SW is not just "any small button battery." It belongs to a specific silver oxide watch battery family. A battery with similar diameter and height may fit physically, but it may not provide the same voltage stability or service life.

SR626SW Battery Equivalent and Cross Reference

The most common SR626SW equivalent is 377. Depending on the brand and region, the same battery family may also appear as SR626, SR66, V377, D377, SG4, SB-AW, or other cross-reference codes. These codes are common in watch repair, battery packaging, and replacement guides.

Code	Typical Meaning	Replacement Comment
SR626SW	Original silver oxide low-drain code	Correct battery type for many analog watches
377	Common watch battery replacement code	Usually the most common SR626SW equivalent
SR626	Short-form silver oxide size code	Usually points to the same size family
SR66	Alternative silver oxide reference	Common in cross-reference charts
V377	Varta-style reference	Usually compatible when silver oxide type is confirmed
D377	Duracell-style reference	Usually compatible when silver oxide type is confirmed
AG4	Alkaline battery with similar size	May fit physically, but not preferred for most watches
LR626	Alkaline version of similar size	Possible physical fit, but lower voltage stability than silver oxide

When checking an SR626SW battery equivalent, compare the code, chemistry, size, and application. The Coin & Button Cell Battery Cross-Reference Guide can be used to check common battery codes before choosing a replacement, especially when the original battery uses a brand-specific marking instead of SR626SW or 377.

Is SR626SW the Same as a 377 Battery?

In most watch battery replacement situations, SR626SW and 377 are treated as equivalent. A 377 battery is commonly used as a direct replacement for SR626SW in analog watches, miniature clocks, and low-drain electronic devices.

Energizer lists the 377 watch battery as a silver oxide cell used for watches, toys, glucose monitors, and calculators, with replacement references including 376/377, D377, SB-AW, SR626SW, and SR66. (Energizer, 377 Watch Battery)

Replacement Question	Practical Answer
Can 377 replace SR626SW?	Yes, in most analog watches and low-drain devices.
Is 377 silver oxide?	Usually yes. Always confirm chemistry on the package or datasheet.
Is 377 better than AG4 for watches?	Usually yes, because 377 is typically silver oxide and has more stable voltage.
Can LR626 replace SR626SW?	It may fit physically, but it is alkaline and not ideal for many watches.

The safest practical rule is simple: if the original battery is SR626SW, choose a 377 silver oxide replacement rather than a cheaper alkaline AG4 or LR626 unless the device manual specifically allows alkaline chemistry.

How to Read the SR626SW Battery Code

Battery codes are useful because they describe chemistry, size, and sometimes discharge type. Understanding the code helps avoid incorrect replacements.

Code Part	Meaning	Example in SR626SW
SR	Silver oxide chemistry	SR626SW uses silver oxide chemistry
LR	Alkaline chemistry	LR626 is the alkaline version with similar size
626	Approximate size class	About 6.8mm diameter and 2.6mm height
SW	Low-drain silver oxide type	Commonly used in analog watches
W	Higher-drain silver oxide type in some coding systems	Used where the device needs different discharge capability

This is why SR626SW and LR626 should not be treated as identical just because the "626" size code is similar. The chemistry prefix changes the discharge behavior.

Silver Oxide vs Alkaline: Why Chemistry Matters

SR626SW and 377 are silver oxide cells. AG4 and LR626 are usually alkaline cells with a similar physical size. In many low-cost devices, alkaline may work. In watches, silver oxide is normally preferred because it provides a flatter discharge curve and more stable operating voltage.

Maxell describes silver oxide button batteries as having high energy per unit volume and stable operating voltage, with applications including watches, measuring instruments, calculators, medical instruments, and BLE devices. Maxell also separates SR silver oxide button batteries from LR alkaline button batteries by application category. (Maxell, SR Silver Oxide Battery and LR Button Battery)

Feature	Silver Oxide SR626SW / 377	Alkaline AG4 / LR626
Nominal voltage	1.55V	1.5V
Voltage stability	More stable during discharge	Voltage drops more gradually during discharge
Typical watch use	Preferred	May work, but not ideal
Service life in low-drain watches	Usually longer and more predictable	Often shorter
Best use case	Analog watches, precision low-drain devices	Low-cost toys, simple electronics, non-critical devices

For a watch battery replacement, chemistry is often more important than price. A cheaper alkaline equivalent may save a small amount at replacement time but can lead to shorter service life, unstable operation, or earlier replacement.

SR626SW vs SR626W

SR626SW and SR626W are physically similar silver oxide batteries, but the suffix may indicate different discharge characteristics. In many replacement charts, they may appear close together, but they are not always the same recommendation for every device.

Code	Typical Meaning	Common Use
SR626SW	Silver oxide, low-drain type	Analog watches and low-drain devices
SR626W	Silver oxide, higher-drain type in many coding systems	Devices with higher current demand or special functions

If the original battery was SR626SW, a 377 silver oxide replacement is usually the safer choice. If the original battery was marked SR626W, check the device manual or original manufacturer recommendation before substituting a low-drain cell.

How to Confirm SR626SW Size Before Replacement

Button cell size differences can be small. A battery that is slightly too thick may stress the battery contact or prevent the case back from closing properly. A battery that is too thin may create poor contact and intermittent operation.

Before installing a replacement, check these points:

• The diameter should be close to 6.8mm.
• The height should be close to 2.6mm.
• The positive and negative sides should match the device's polarity marking.
• The holder should close without forcing the battery.
• The battery should sit flat and make stable contact with the spring terminal.

If a watch stops after replacement, do not immediately assume the new battery is defective. Poor contact, reversed polarity, a loose battery clamp, dirt on the contact, or a protective insulating tab can cause the same symptom.

What to Check If the Watch Does Not Work After Battery Replacement

A new SR626SW or 377 battery may still fail to power a watch if the installation or contact condition is poor. This is common in older watches, watches with oxidized contacts, or devices where the battery spring has lost tension.

Problem	What to Check
No movement after replacement	Check polarity, contact position, and whether the battery is fully seated.
Watch starts then stops	Check for weak contact pressure or contamination on the battery surface.
Battery fits too tightly	Confirm height and diameter; do not force a thicker cell into the holder.
Short service life	Confirm that the replacement is silver oxide, not alkaline AG4 or LR626.
Intermittent operation	Check battery clip, spring terminal, corrosion, and case pressure.

Use clean plastic tweezers or gloves where possible. Oil, dirt, or fingerprints on a small button cell can affect contact quality in compact watch holders.

Common Brand References for SR626SW and 377

Different brands may print different codes on the same replacement family. This is one reason a cross-reference table is useful, especially when a watch manual lists one code but the available battery package shows another.

Brand or Label Type	Common Marking
Renata	377
Energizer	377
Maxell	SR626SW / 377
Sony	SR626SW
Varta	V377
Duracell	D377
Seiko reference	SB-AW
Citizen reference	280-39

Brand markings can vary by region and packaging. The safest method is to verify the battery code, chemistry, size, voltage, and intended application rather than relying on one printed number alone.

Common Mistakes When Replacing SR626SW Batteries

Most SR626SW replacement problems come from choosing a physically similar battery without checking chemistry or from installing the battery with poor contact.

• Using AG4 or LR626 when a silver oxide 377 is preferred.
• Assuming every 6.8mm button battery has the same discharge behavior.
• Forcing a battery into a holder when the height is not correct.
• Installing the battery with reversed polarity.
• Touching the battery surface with dirty or oily fingers.
• Mixing old and new cells in devices that use multiple batteries.
• Ignoring corroded contacts or weak spring pressure inside the battery compartment.

Button cells are small, but replacement still requires careful handling. Correct chemistry, clean contacts, and proper seating are often the difference between a successful watch repair and an intermittent failure.

SR626SW Battery Quick Reference Table

Question	Answer
What is the most common SR626SW equivalent?	377 battery.
Is SR626SW the same as 377?	In most watch replacement cases, yes.
Is SR626SW silver oxide?	Yes, SR626SW is a silver oxide button cell.
What voltage is SR626SW?	1.55V nominal.
What size is SR626SW?	Approximately 6.8mm diameter and 2.6mm height.
Can AG4 replace SR626SW?	It may fit physically, but it is alkaline and not preferred for most watches.
Can LR626 replace SR626SW?	It may fit physically, but a silver oxide 377 is usually the better replacement.
What should I choose for an analog watch?	Choose SR626SW or 377 silver oxide unless the watch manufacturer specifies otherwise.

SR626SW is best treated as a silver oxide watch battery family, with 377 being the most common equivalent. AG4 and LR626 may share a similar size, but they are alkaline alternatives and are not the best choice for many watches. A reliable replacement should match the original battery's size, voltage, chemistry, and discharge requirement.

For watches and precision low-drain electronics, the practical choice is usually a 377 silver oxide battery. Checking the cross-reference code, confirming silver oxide chemistry, and inspecting the battery contacts before installation helps avoid short service life, unstable operation, or incorrect battery selection.