SR626SW 377 376 LR626 LR66 AG4 177 Battery Equivalent Guide
If you open a watch and find a tiny button cell marked SR626SW, 377, 376, LR626, LR66, AG4, or 177, it is easy to assume that every number means exactly the same battery. The situation is slightly more complicated. These codes normally point to the same compact 6.8 mm by 2.6 mm battery size, but they can represent different battery chemistry and different discharge behavior.
For most traditional analog watches, the SR626SW battery, commonly sold as a 377 battery, is usually the preferred choice because it uses silver oxide chemistry and provides a stable nominal voltage of 1.55V. The 376 battery is closely related and is generally associated with the SR626W high-drain version. Meanwhile, LR626, LR66, and AG4 normally refer to alkaline batteries with a nominal voltage around 1.5V.
This difference matters. A battery may fit perfectly inside a watch and make it run, but physical fit alone does not always mean it is the best long-term replacement. This guide explains the real relationship between SR626SW, 377, 376, LR626, LR66, AG4 and 177 batteries so that buyers, repair shops, watch owners and electronic component suppliers can choose the correct option with confidence.
Quick Answer: What Is the Best SR626SW Battery Equivalent?
For most applications that originally specify an SR626SW battery, the 377 battery is the closest common commercial equivalent. Both are normally silver oxide cells with a nominal voltage of 1.55V and a physical size of approximately 6.8 mm in diameter and 2.6 mm in height.
A 376 battery has the same basic size and voltage, but it is traditionally associated with SR626W, a high-drain silver oxide design. Some modern battery manufacturers sell a combined 377/376 battery designed to cover both applications.
LR626, LR66 and AG4 batteries are usually alkaline cells. They have almost the same dimensions and approximately 1.5V nominal voltage, so they may operate many devices designed for an SR626SW. However, their discharge curve and useful life may be different. For precision watches, a silver oxide 377 or SR626SW is normally a better choice than an alkaline LR626 or AG4.
SR626SW Battery Specifications at a Glance
| Specification | SR626SW / 377 |
|---|---|
| Battery type | Silver oxide button cell |
| Nominal voltage | 1.55V |
| Diameter | Approximately 6.8 mm |
| Height | Approximately 2.6 mm |
| Typical application | Analog watches and other low-drain electronics |
| Common commercial code | 377 |
| Related high-drain version | SR626W / 376 |
| Common alkaline alternatives | LR626, LR66, AG4 |
| Rechargeable | No |
Capacity can vary between manufacturers and test conditions. This is why buyers should avoid judging a battery only by a single advertised mAh number. Voltage stability, discharge load, manufacturing quality, storage conditions and the requirements of the watch movement can be more important than a small difference in rated capacity.
What Does SR626SW Mean?
The code SR626SW contains useful information about the battery. The letters and numbers are not simply a random product name.
- S identifies silver oxide chemistry.
- R indicates a round cell.
- 626 identifies the approximate physical size class, about 6.8 mm in diameter and 2.6 mm high.
- SW is commonly used for a low-drain watch battery configuration.
The low-drain design is especially suitable for simple quartz analog watches. These movements use very little power continuously. They do not normally need large bursts of current, but they benefit from predictable voltage over a long operating period.
This is one reason the search term SR626SW watch battery is so common. The battery was designed around the electrical demands of precision miniature devices where stable operation is more important than delivering a large burst of power.
SR626SW vs 377 Battery: Are They the Same?
In normal consumer use, SR626SW and 377 battery are treated as equivalent designations. If the old battery inside an analog watch is marked SR626SW and the replacement package says 377 silver oxide, that is usually the correct match.
A 377 watch battery normally provides 1.55V and uses the same 6.8 mm × 2.6 mm physical format. Major battery manufacturers and cross-reference systems commonly connect 377 with SR626SW.
Therefore, when someone searches for a 377 battery equivalent, SR626SW is one of the most important codes to understand. The relationship works in both directions: a person searching for an SR626SW battery replacement will frequently find a product labeled 377, while someone who removes a 377 battery from a watch may find SR626SW printed on the replacement package.
The important detail is chemistry. For the closest replacement, choose a 377 that is clearly identified as silver oxide. Do not assume that every inexpensive battery carrying several cross-reference numbers provides exactly the same electrical performance.
SR626SW vs 376 Battery: What Is the Difference?
The relationship between 376 and 377 causes more confusion than almost any other battery code in this size.
Traditionally, 377 corresponds to SR626SW, the lower-drain version, while 376 corresponds to SR626W, the higher-drain version. Both silver oxide batteries are approximately 6.8 mm in diameter, 2.6 mm high and rated at 1.55V.
The difference is mainly related to how the battery is designed to deliver current. A basic analog quartz watch usually places a very small continuous load on its battery. This is where an SW-type battery makes sense. A more complicated device may require higher current or occasional current pulses. A W-type design is intended to deal better with these loads.
However, the modern market is less rigid than the old numbering system suggests. Some manufacturers sell one product labeled 377/376 and design it to support continuous low drain together with higher pulse demand. This explains why a shopper researching battery 376 377 may see both numbers printed on one blister pack.
The practical rule is simple: if your device specifically requests SR626SW or 377, a quality silver oxide 377 is the natural first choice. If it specifies SR626W or 376, look for a suitable high-drain or manufacturer-approved 376/377 product.
SR626SW vs LR626: Same Size Does Not Mean Same Chemistry
An LR626 battery equivalent discussion should always include chemistry. LR626 normally refers to a zinc-manganese dioxide alkaline button cell, while SR626SW refers to a silver oxide battery.
The two batteries are physically very close. A typical LR626 is about 6.8 mm wide and 2.6 mm high. Its nominal voltage is approximately 1.5V. This allows it to fit and operate in many devices that can also accept an SR626SW.
But an alkaline LR626 generally does not maintain its voltage as evenly throughout discharge as a good silver oxide battery. Its effective operating life can also be shorter in a low-drain precision watch.
That means LR626 can be a practical alternative for inexpensive toys, small electronic gadgets or temporary use, but it is not automatically the best SR626SW battery equivalent for a quality wristwatch.
When Should You Choose SR626SW Instead of LR626?
- When the watch originally specifies SR626SW or 377.
- When accurate long-term timekeeping matters.
- When you want stable voltage during most of the battery life.
- When replacing a battery in a valuable or difficult-to-open watch.
- When longer service intervals are more important than the lowest battery price.
When Can LR626 Make Sense?
- For low-cost electronic toys.
- For simple calculators or small novelty electronics.
- For temporary testing.
- When the device specifically lists LR626 or AG4.
- When alkaline chemistry is approved by the device manufacturer.
What About LR66 and AG4 Batteries?
LR66 and AG4 are commonly associated with the same alkaline button-cell size as LR626. In online stores, the package may carry several names at once, such as AG4, LR626, LR66 and 177.
This naming is useful for cross-reference searches, but buyers should still read the chemistry line. An AG4 marked 1.5V alkaline should not be described as chemically identical to an SR626SW silver oxide battery.
The dimensions allow many of these batteries to be physically interchangeable, but their electrical behavior is different. This distinction becomes especially important in watches because a watch may run for months or years from one tiny battery. A small difference in the discharge profile can matter far more in a watch than in a toy that is only used occasionally.
What Is a 177 Battery?
The 177 battery appears in many cross-reference lists around the SR626, 377 and LR626 size family. Depending on the manufacturer and product line, 177 may appear alongside LR626, AG4, LR66, 376 or 377 references.
For that reason, the number 177 by itself should not be your only purchasing criterion. Check the old cell, device manual or new battery packaging for three things: physical size, voltage and chemistry.
If you are replacing a silver oxide SR626SW watch battery, selecting a known 1.55V silver oxide 377 is usually clearer than buying an unknown product simply because the listing includes the number 177.
SR626SW, 377, 376, LR626, LR66, AG4 and 177 Comparison
| Battery Code | Typical Chemistry | Nominal Voltage | Approx. Size | Best Known Use |
|---|---|---|---|---|
| SR626SW | Silver oxide | 1.55V | 6.8 × 2.6 mm | Low-drain analog watches |
| 377 | Silver oxide | 1.55V | 6.8 × 2.6 mm | Common SR626SW watch replacement |
| 376 | Silver oxide | 1.55V | 6.8 × 2.6 mm | Higher-drain SR626W applications |
| LR626 | Alkaline | 1.5V | 6.8 × 2.6 mm | Small electronics and general use |
| LR66 | Usually alkaline | About 1.5V | 6.8 × 2.6 mm | Alternative naming for this size family |
| AG4 | Usually alkaline | About 1.5V | 6.8 × 2.6 mm | Toys, calculators and low-cost electronics |
| 177 | Varies by manufacturer reference | Check package | Commonly 6.8 × 2.6 mm class | Cross-reference designation |
Silver Oxide vs Alkaline: Why Chemistry Matters in a Watch
One of the most useful ways to understand the SR626SW battery equivalent question is to forget the product numbers for a moment and look at the chemistry.
Silver oxide batteries are valued in watches because their output stays relatively stable during most of the discharge cycle. A quartz movement is a precision electronic system. Stable power helps the movement operate predictably until the battery approaches the end of its useful life.
Alkaline button cells are less expensive to manufacture and can be perfectly suitable for many small devices. However, their voltage generally decreases more gradually during use. In some devices this does not matter. In a precision watch, a silver oxide battery is often the more appropriate solution.
This is why replacing an SR626SW watch battery with an AG4 only because both batteries physically fit is not always the best decision. The better question is not simply, "Will it fit?" The better question is, "Does it match the chemistry and load requirements of the original battery?"
Why the 377 Watch Battery Is So Common
The compact dimensions of the 377 watch battery make it suitable for many small analog quartz watches. At only about 6.8 mm across and 2.6 mm thick, it fits inside slim watch cases while still providing enough energy for extremely efficient movements.
A quartz watch consumes very little electrical energy. Instead of requiring large continuous power, the movement needs a small, dependable supply over a long period. This makes the discharge characteristics of silver oxide chemistry a strong match for traditional watch design.
As a result, searches such as 377 battery for watch, battery 377 watch, 377 watch battery and watch battery SR626SW often describe essentially the same replacement problem.
SR626SW Watch Battery for Analog and Multifunction Watches
The letters at the end of the battery number can provide an important clue. An SR626SW watch battery is traditionally aimed at low-drain equipment such as a simple analog quartz watch.
A multifunction watch with an alarm, illumination system or other features can create higher electrical demand. In these applications, an SR626W or related 376 high-drain design may be more suitable.
Modern combined products can reduce this distinction. For example, a manufacturer may offer one 377/376 silver oxide cell designed for continuous low-drain operation while also supporting pulse demand. Always follow the watch manufacturer's specification when it is available.
Is ST626SW a Real Replacement Code?
People sometimes search for terms such as ST626SW watch battery after reading very small text on the back of a watch or seeing an online product listing. However, SR626SW is the widely recognized battery designation.
If you see ST626SW in a marketplace listing, do not assume that it represents a separate standardized chemistry. Check whether the actual replacement battery is identified as SR626SW, SR626W, 377, 376 or another recognized code. Tiny engraved letters are also easy to misread.
When in doubt, compare the original battery itself rather than relying only on text printed on the watch case.
Maxell SR626SW Battery: Why Brand Specifications Matter
The Maxell SR626SW battery is a useful example of why a reliable manufacturer specification gives more information than a generic marketplace title.
Maxell identifies SR626SW as a 1.55V silver oxide low-drain cell with a diameter of approximately 6.8 mm and a height of approximately 2.6 mm. Its published data also separates SW low-drain products from W high-drain products.
That distinction helps buyers understand that two button cells with identical dimensions may still be optimized for different electrical loads.
When buying a Maxell 626SW, Maxell SR626SW battery or another major-brand equivalent, check the actual model printed on the packaging rather than depending entirely on a seller's keyword list.
What About a Sony SR626SW Watch Battery?
Search terms such as watch battery SR626SW Sony, SR626SW watch battery Sony and watch battery Sony SR626SW remain common because many users remember Sony-branded watch batteries or remove an older branded battery from a device.
From a replacement point of view, the brand name should not be the first compatibility test. The important information is the battery code, physical dimensions, voltage and chemistry.
If an older Sony-branded cell is marked SR626SW or 377, look for a reputable silver oxide replacement with the matching specification. A Maxell SR626SW, suitable 377 silver oxide cell or another correctly specified product may be a better purchasing reference than trying to find an identical old package design.
How to Choose the Correct SR626SW Battery Replacement
Step 1: Read the Old Battery
The safest starting point is the number printed directly on the original battery. Look for codes such as SR626SW, 377, SR626W, 376, LR626 or AG4.
Step 2: Identify the Chemistry
If the original cell is SR626SW, choose silver oxide when possible. If it is LR626 or AG4 and the device manufacturer specifies alkaline chemistry, use the recommended type.
Step 3: Confirm the Size
The SR626 family is approximately 6.8 mm in diameter and 2.6 mm high. Do not select a battery only because its voltage is similar. Button cells with different diameters or thicknesses may fail to contact the terminals correctly or may damage the battery holder.
Step 4: Match the Drain Type When Necessary
For a simple analog quartz watch, SR626SW or 377 is normally the logical choice. For equipment requiring higher current, check whether the specified battery is SR626W or 376.
Step 5: Buy Fresh Stock
Storage history matters. A high-quality battery that has spent years in poor storage conditions may deliver less useful life than fresh stock from a reliable supplier.
Step 6: Check the Packaging
Avoid relying on product titles containing dozens of battery numbers. A listing that says "AG4 LR626 SR626SW 377 376 177" may be designed for search visibility rather than technical precision. Check whether the cell is actually silver oxide or alkaline.
Why a Cheap AG4 May Run a Watch but Still Be a Poor Replacement
This is one of the most important practical points in the entire guide.
Imagine that a watch originally uses an SR626SW. You install an AG4 alkaline battery. The dimensions are correct, the contacts touch and the watch begins to move. It is tempting to conclude that the two batteries are completely identical.
But successful startup only proves basic electrical compatibility at that moment. It does not prove that the replacement will provide the same voltage stability or service life.
This is why professionals often prefer a true silver oxide SR626SW battery equivalent such as a 377 when servicing watches. The price difference for one tiny cell is usually small compared with the time required to reopen the watch.
How Long Does an SR626SW Battery Last?
There is no single operating-life number that applies to every watch. Battery life depends on the watch movement, circuit design, mechanical condition, current draw, temperature, battery quality and storage history.
A very efficient analog movement can operate for a long period because it requires extremely little current. A dirty or mechanically damaged movement may consume more energy and shorten battery life even when a high-quality battery is installed.
This creates an important diagnostic lesson: if a new 377 battery becomes empty unusually quickly, the battery may not be the real problem. The watch itself may need inspection.
Why Your New 377 Battery May Appear Dead
If a freshly installed 377 or SR626SW does not start the watch, check more than the battery.
- Confirm that positive and negative sides are installed correctly.
- Check whether the retaining clip is properly seated.
- Look for dirt, corrosion or oil on the electrical contacts.
- Confirm that the battery is the correct thickness.
- Check whether an insulating tab must be moved or reset.
- Make sure the watch movement is not mechanically blocked.
- Test the cell with suitable equipment if available.
Repeatedly installing different batteries without investigating the watch can waste good cells and hide the actual fault.
How to Install an SR626SW or 377 Watch Battery Correctly
Button cells are small, and good handling practice helps protect both the battery and the watch.
- Work on a clean, well-lit surface.
- Note the orientation of the original battery before removal.
- Use appropriate watch tools rather than sharp improvised objects.
- Avoid short-circuiting the positive and negative surfaces with metal tools.
- Keep the battery and watch contacts clean.
- Install the replacement in the same orientation as the original.
- Confirm the retaining clip is secure.
- Check that the movement starts before closing the case.
- Replace seals correctly when water resistance is important.
For valuable, waterproof or complicated watches, professional battery replacement may be worthwhile because opening and resealing the case incorrectly can create problems unrelated to the battery itself.
SR626SW Battery Equivalent Buying Checklist
Before ordering an SR626SW battery equivalent online, check these points:
- Code: SR626SW or 377 for a typical low-drain silver oxide replacement.
- Chemistry: Silver oxide when replacing an original SR626SW.
- Voltage: Normally 1.55V for the silver oxide version.
- Size: Approximately 6.8 mm × 2.6 mm.
- Drain requirement: SW/377 for typical low-drain use; W/376 where high-drain performance is specified.
- Manufacturer: Choose a reputable source with clear technical labeling.
- Freshness: Prefer stock with good storage history.
- Packaging: Avoid damaged or poorly identified cells.
Common Mistakes When Buying a 377 Battery
Mistake 1: Assuming Every 6.8 × 2.6 mm Battery Is Identical
Physical dimensions are only one part of compatibility. Chemistry and discharge behavior matter too.
Mistake 2: Treating AG4 and SR626SW as Chemically Identical
They can share similar dimensions, but AG4 normally means alkaline while SR626SW means silver oxide.
Mistake 3: Ignoring 376 vs 377 Drain Characteristics
These two codes can be sold together today, but historically they identify different silver oxide drain configurations.
Mistake 4: Buying by Price Alone
Changing a watch battery takes time. Saving a very small amount on the cell may not be worthwhile if the replacement offers shorter service life.
Mistake 5: Believing Every Cross-Reference List Is Exact
Online sellers often combine many keywords to make a product easier to find. Always check the actual chemistry and specifications.
SR626SW Battery Names in Different Markets
One reason this battery creates so many search queries is that consumers, watchmakers and battery manufacturers use several naming systems.
A shopper in the United States may search for a 377 battery. Another buyer may ask for an SR626SW battery. An online electronics store may list SR66 or 377 alongside the product. A low-cost alkaline version may be sold as LR626, LR66 or AG4.
This means global buyers should compare the underlying specification rather than assuming that the most familiar local number is the only correct name.
For international sourcing, the most useful description is often: SR626SW / 377, 1.55V silver oxide, approximately 6.8 × 2.6 mm. This gives the supplier more technical information than simply asking for "a small watch battery."
SR626SW Battery for Watches, Calculators and Small Electronics
Although watches are the best-known application, this battery size can appear in several compact electronic devices. Depending on the manufacturer's design, the same physical format may be found in small calculators, measuring tools, miniature electronic modules and other low-power products.
However, users should not automatically move one battery type between different devices. A calculator that accepts an alkaline LR626 does not prove that an expensive watch should also use LR626 instead of its specified SR626SW.
Always give the original device specification priority over a generic equivalent table.
Which Is Better: SR626SW, 377 or LR626?
For an analog watch designed for silver oxide chemistry, SR626SW and 377 are generally the best choices. They provide the correct silver oxide chemistry, approximately 1.55V output and the correct physical size.
LR626 can be useful when alkaline chemistry is specifically allowed or when low cost is more important than maximum performance. But it should be considered a physical and approximate voltage alternative rather than a perfect chemical duplicate of SR626SW.
Therefore, asking "Which battery fits?" and asking "Which battery is best?" can produce different answers. Several batteries may fit. The best one is the battery that most closely matches the original electrical specification.
Frequently Asked Questions About SR626SW and 377 Batteries
Is a 377 battery the same as an SR626SW battery?
For normal replacement purposes, yes. A 377 silver oxide battery is commonly used as the commercial equivalent of SR626SW. Both normally provide 1.55V and measure approximately 6.8 mm × 2.6 mm.
What is the best SR626SW battery equivalent?
A quality 377 silver oxide battery is generally the closest replacement for an SR626SW. Check the device specification before substitution.
Can I replace SR626SW with LR626?
An LR626 normally has a similar physical size and around 1.5V nominal voltage, so it may operate some devices. However, LR626 is typically alkaline while SR626SW is silver oxide. For a watch originally designed for SR626SW, a 377 silver oxide battery is usually the better replacement.
Is AG4 equivalent to SR626SW?
AG4 is commonly similar in size to SR626SW, but it normally uses alkaline chemistry. It can therefore be considered a size-compatible alternative in many applications rather than a technically identical replacement.
What is the 377 battery equivalent?
The most important 377 battery equivalent is SR626SW. Depending on the manufacturer, packaging may also list SR66 and other cross-reference codes.
What is the LR626 battery equivalent?
Common names associated with the LR626 size include LR66 and AG4. SR626SW and 377 share very similar dimensions but normally use silver oxide chemistry instead of alkaline chemistry.
Are 376 and 377 batteries interchangeable?
They have the same basic 6.8 mm × 2.6 mm size and 1.55V silver oxide chemistry. Traditionally, 377 corresponds to low-drain SR626SW while 376 corresponds to high-drain SR626W. Some modern manufacturers combine 377 and 376 into one product designed for a broader load range.
Can I use a 376 battery instead of a 377 watch battery?
In many devices the physical and voltage requirements allow it, and some batteries are specifically marketed as 377/376. For the most precise replacement, follow the original watch specification or the battery manufacturer's cross-reference information.
Is a 377 watch battery rechargeable?
No. Standard 377 and SR626SW silver oxide button cells are primary, non-rechargeable batteries. Do not attempt to recharge them.
What voltage is an SR626SW watch battery?
A standard silver oxide SR626SW watch battery has a nominal voltage of approximately 1.55V.
What size is an SR626SW battery?
The SR626SW size is approximately 6.8 mm in diameter and 2.6 mm in height.
Is Maxell SR626SW the same size as a 377?
Yes. Maxell SR626SW belongs to the same 6.8 mm × 2.6 mm silver oxide watch battery size commonly associated with the 377 designation.
What should I buy if my watch says SR626SW?
Choose a reputable 1.55V silver oxide battery marked SR626SW or 377. This is generally a better match than choosing an alkaline AG4 or LR626 simply because it fits.
Final Recommendation: Match Chemistry Before the Number
The biggest lesson from the SR626SW 377 376 LR626 LR66 AG4 177 family is simple: battery numbers tell only part of the story.
If your watch originally uses SR626SW, a quality 377 silver oxide battery is usually the most direct replacement. It provides the expected 1.55V nominal voltage, correct 6.8 × 2.6 mm dimensions and low-drain characteristics suitable for many analog quartz watches.
The 376 battery is closely related but traditionally corresponds to the higher-drain SR626W specification. Modern 377/376 batteries may combine the requirements of both categories.
LR626, LR66 and AG4 are useful alternatives in the same general physical size, but they are normally alkaline batteries. They can work in many small electronic devices, yet they should not automatically be treated as identical to SR626SW.
For buyers searching for an SR626SW battery equivalent, 377 battery equivalent, LR626 battery equivalent, SR626SW watch battery, 377 watch battery, watch battery SR626SW Sony or Maxell SR626SW battery, the safest approach is always the same: confirm the size, voltage, chemistry and drain requirements before buying.
A button battery costs very little compared with the watch or electronic device it powers. Choosing the technically correct battery rather than the first cell that physically fits can provide more predictable performance, fewer battery changes and better long-term reliability.
