What is SR621SW?

SR621SW Battery Specifications

Applications and Uses of SR621SW Battery

Replacement Products for SR621SW

Steps to Replace an SR621SW Battery

Difference Between SR621SW and SR626SW

Frequently Asked Questions

Definition

SR621SW is a widely used button cell battery. It belongs to the silver oxide (Silver Oxide) battery family. It is known for stable output voltage, high energy density, and long service life. This battery uses a silver oxide chemical system to provide energy. Its production follows modern environmental standards, so the impact on the environment is small during use and disposal.

Shape

The SR621SW battery has a standard button shape. It has a metal positive cap and a metal negative case. It is small and usually silver in color. This design makes it easy to fit into many small electronic devices. It also gives good electrical contact and mechanical stability.

Naming

The name SR621SW follows an international coding system:

• SR: Chemistry and shape. "S" means silver oxide (Silver Oxide). "R" means round (Round).
• 6: Battery diameter, about 6.8 mm.
• 21: Battery height, about 2.15 mm.
• SW: Mercury-free standard. "S" comes from the Japanese JIS standard. "W" means mercury-free.

Features

SR621SW batteries have these key features:

• Stable voltage: Very steady and accurate 1.55V output during its life cycle.
• High capacity: High energy density compared to small size.
• Long life: Usually lasts for years.
• Mercury-free: Meets environmental standards.

Basic Electrical Parameters

Main parameters of SR621SW:

• Nominal voltage: 1.55V
• Standard capacity: about 15–20mAh (milliampere hour)
• Chemistry: Silver oxide
• Operating temperature: 0°C to 60°C
• Self-discharge rate: <5% per year

Physical Dimensions

Exact size specifications:

• Diameter (D): 6.8 mm
• Height (H): 2.15 mm
• Weight: about 0.6 g

Comparison table:

Other Common Equivalent Models

SR621SW has several equivalents in global markets:

• IEC standard: SR721
• JIS standard: SR721
• Common names: 364, 364X, AG1, G1, S736E

Main Application Areas

SR621SW is small and stable. It is often used in miniature electronic devices where size and voltage accuracy are very important. Its stable output voltage makes it ideal for precision timing devices and measuring instruments. These devices need long-term accuracy.

Compared with alkaline batteries, SR621SW performs better in precision devices. Silver oxide batteries show a flat voltage curve, with changes less than 0.1V. Alkaline batteries show a clear drop, which can cause problems in voltage-sensitive devices.

Common Device Examples

SR621SW is widely used in:

• Mini calculators and electronic dictionaries
• Laser pointers and presentation devices
• Small LED flashlights
• Watches, clocks, timers
• Electronic toys and games
• Car key remotes
• Medical devices (e.g., glucose meters)
• Electronic card holders and gifts
• Small electronic promotional items

Battery life examples:

• In digital watches: 24–36 months of power.
• In laser pointers (intermittent use): 12–18 months of power.

Direct Equivalent Models

Direct equivalents for SR621SW include:

• SR721 (IEC/JIS standard)
• 364/364X (common in the US)
• AG1/G1 (other names)

They have the same electrical and physical properties. They can be safely interchanged. Use silver oxide batteries for best performance.

Models Not Recommended as Replacements

Some similar-sized models are not suitable:

• LR621: Same size but alkaline type. Voltage 1.5V, lower capacity, less stable. Capacity drop is 40% faster than silver oxide. Not good for precision devices.
• CR621: A lithium metal (Lithium Metal) battery. Very rare and not compatible.

Comparison tests show: after 300 hours of discharge, SR621SW keeps 85% of its capacity. Alkaline batteries keep only 60%.

Preparation

Before replacing, prepare:

• A new SR621SW battery
• Anti-static gloves or dry hands
• Proper tools (plastic spudger, small flat screwdriver)
• Clean soft cloth and cotton swabs
• Magnifying glass (for small compartments)

Safety Notes

• Do not short-circuit battery terminals with metal tools.
• Install battery in correct polarity.
• Recycle old batteries. Do not throw away.
• Avoid replacing in humid environments.
• Keep away from fire and heat.

Detailed Steps

1. Open the battery compartment: Use tools carefully.
2. Remove old battery: Note the polarity ("+" side up or down). Use plastic tool to lift.
3. Clean compartment: Use dry swab or cloth.
4. Insert new battery: Place with correct polarity (usually "+" side up).
5. Close cover: Lock tightly and test the device.

Core Differences

Performance Analysis

SR626SW has more capacity because it is thicker. Tests show SR626SW lasts about 40% longer than SR621SW under the same load. But devices must have enough space for the thicker battery.

Compatibility Summary

Both batteries have the same diameter, but SR626SW is taller and has higher capacity. They are not directly interchangeable. A device made for SR621SW may not close properly with SR626SW.

Measurements show the height difference is 20.9%. Always follow the device maker’s specification to avoid damage.

What battery is equivalent to sr621sw?

The SR621SW battery is compatible with models such as Renata 364, AG1, LR621, and 164, as they all share identical dimensions (6.8 x 2.1 mm) and a voltage of 1.55V.

What is the Renata equivalent to SR621SW?

The Renata 364 is equivalent to a silver oxide button cell, with identical dimensions (6.8 x 2.1 mm) and a voltage of 1.55V.

Are 364 and 377 batteries interchangeable?

The 364 and 377 batteries are not compatible. The two batteries have the same 6.8 mm diameter and 1.55V voltage. However, the 377 (2.6 mm) is thicker than the 364 (2.1 mm).

What is SR626SW also known as?

The SR626SW battery is also referred to as 377, AG4, or LR626, with the designation varying by manufacturer and battery type.