AG4, LR626, LR66, 177/376/377, SR626, SR626SW Battery Equivalents

AG4, LR626, LR66, 177/376/377, SR626, SR626SW batteries are very popular non-rechargeable button/coin cell batteries, available in several chemistries and manufactured by practically all battery brands. These batteries are commonly found in wrist watches and similar small electronic devices requiring a reliable power source.

energizer 376 377 sr626sw battery

SR626SW, LR626, 377, AG4 Battery Features and Specifications

AG4, LR626, 376/377, SR626, SR626SW, etc. batteries are 6.8 mm in diameter and 2.6 mm in height.

According to the IEC standard, these batteries should be labeled LR626 (alkaline) or SR626 (silver-oxide) and according to the ANSI standard 1176SO battery.

Sometimes shorter, two-digit code is used: LR66 for alkaline and SR66 for silver-oxide batteries.

Many manufacturers use their own labels for these batteries, but they also tend to add IEC and other standard codes, including short descriptions about the chemistry, nominal voltage, battery equivalents, and similar.

LR626 (alkaline) or SR626 (silver-oxide) capacities depend on the chemistry, but also a cut-off voltage of the used device - alkaline batteries voltage quickly drops, making them no so suitable for electronic devices like wrist watches and similar. Since these batteries are rather small, so is their price per one battery. For short, if you need LR626/SR626 wrist watch battery, go for an SR626 or SR626SW battery.

Few notes:

duracell 377 battery- AG4 vs SG4: AG4 should be 'alkaline G4' and SG4 should be 'silver-oxide G4' battery. However, sometimes manufacturers mark silver-oxide batteries with both SG4 (correct) and AG4 (not correct) to emphasize that their battery is a replacement for AG4/SG4/LR66/SR66/LR626/SR626/SR626SW battery.

- if the battery code starts with the 'L', then it should be alkaline 626 battery (LR626, LR66, AG4),

- if the battery code starts with the 'S', then it is a 'silver-oxide' coin cell (SR626, SR66, SR626SW).

- if the battery code after the digits contains 'P', then it is the battery with potassium hydroxide electrolyte.

- if the battery code after the digits contains 'S', then it is the battery with sodium hydroxide electrolyte.

- if the battery code after the digits doesn't contain 'P' or 'S', then probably that battery contains organic electrolyte - we emphasize 'probably' because some manufacturers simply drop out these letters when labeling their batteries.

- if the battery code after the digits contains 'W', then the battery complies with the IEC 60086-3 watch batteries standard - most manufacturers of '626' batteries label their silver-oxide batteries as SR626SW to emphasize that these batteries are silver-oxide batteries for wrist watches (and if they are good for wrist watches, then they are good for other electronic devices, too).

 LR626 vs. SR626 Batteries Comparison Chart

Comparison and examples of AG4/SG4/LR66/SR66/LR626/SR626/SR626SW batteries are given in the following SR626SW watch battery replacement chart:

Chemistry Alkaline Silver-Oxide
Nominal Voltage 1.5V 1.55V
End-Point Voltage 1.0V 1.2V
Notes Voltage drops over time Very constant voltage
Typical Labels 177, 376, 377, AG4, LR66, LR626 177, 376, 377, AG4, SG4, SR66, SR626, SR626SW
Typical Capacity 15-17 mAh 25-27 mAh

As one can see, LR626/SR626 batteries are available in two different chemistries:

- Alkaline LR/66LR626 batteries have a nominal voltage of 1.5 volts and it relatively quickly drops over time down to 1.0 volts. However, sensitive electronics might have issues operating at such low voltage and may have issues with reliability when using alkaline AG4/LR66/LR626 batteries. Also, their capacity when drained down to 1.0 volts is lower when compared with silver-oxide batteries by some 30% and up to 50% lower when drained down to 1.2 volts.

- Silver-oxide SR626/SR626SW batteries have a nominal voltage of 1.55 volts and it is rather constant over time as the battery is drained. Also, these batteries have a larger capacity providing a much longer operating time for various devices using a single battery replacement.

Note that some silver oxide SR626 batteries are designed as high-drain batteries and are more suitable for digital watches and similar electronic devices, while other SR626 batteries are designed as low-drain batteries and are more suitable for analog watches, thermometers, and similar.

But, most manufacturers today offer so-called multi-drain SR626 batteries, suitable for both digital and analog watches, toys, thermometers, keychain LED flashlights, and similar.

SR626SW, 377, 376 Batteries Comparison Chart

The following cross reference chart lists some of the most popular  SR626, 377, 376 battery models, with their most important features and specifications:

Battery Chemistry Nominal and Cutoff Voltages Capacity Operating Temperature Annual Self-Discharge Rate Discharge Current Datasheet
Energizer 377/376 Silver Oxide 1.55V/1.2V 24 mAh, 47kΩ down to 1.2V @21°C - ~2% @20°C 31μA @1.46V 47kΩ @21°C Energizer 377/376 
muRata SR626 Silver Oxide 1.55V/1.2V 28 mAh, 30kΩ down to 1.2V @23°C -10°C to +60°C - 50μA @1.55V 30kΩ @23°C  muRata SR626 
Renata 376 High Drain Silver Oxide 1.55V/1.2V 27 mAh, 34k8Ω down to 1.2V @20°C -10°C to +60°C  <10% @20°C  44.5μA @1.55V 34k8Ω @20°C  Renata 376 High Drain 
Renata 377 Low Drain Silver Oxide 1.55V/1.2V 24 mAh, 34k8Ω down to 0.9V @20°C -10°C to +60°C <5% @20°C 43.7μA @1.55V 34k8Ω @20°C Renata 377 Low Drain
Varta V 377 MF Silver Oxide 1.55V/1.2V 21 mAh, 47kΩ down to 1.2V @20°C  0°C to +60°C <10% @20°C - Varta V 377 MF 

As one can see, actual performances vary depending on the discharge current and temperature but also depending on the battery age.

Of course, these are just some of the most popular silver-oxide 6.8 x 2.6 mm button/coin cells on the market.

LR626/SR626 Batteries Safety Issues

Modern LR626/SR626 batteries don't contain mercury, cadmium, and other heavy metals or dangerous toxins.

However, these batteries are 'small shiny objects' that may attract kids and pets and due to their dimensions, these batteries are easily swallowed.

If they get swallowed, these batteries may start electrolytic reactions that may cause chemical burns, which are very dangerous.

Although these batteries don't have a 'large' capacity and just ~1.5V, if they get swallowed, be sure to immediately contact the nearest emergency center and to act according to their instructions.

For short: if you need a 6.8 x 2.6 mm button/coin cell battery replacement for your analog or digital watch, thermometer, toy, micro-LED flashlight, or similar electronic device, go for a high-quality SR626SW (376/377) battery from reputable brands with that has many positive reviews.

If You are unsure regarding low-drain or high-drain models, go for a multi-drain SR626SW battery.