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

energizer 376 377 sr626sw batteryAG4, 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 reliable power source.

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 acording 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 SR626 or SR626SW battery.

AG4, SG4, LR66, SR66, LR626, SR626, SR626SW Watch Battery Replacement Chart

Few notes:

- 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 replacement for AG4/SG4/LR66/SR66/LR626/SR626/SR626SW battery.

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

- if the battery code starts with the 'S', than it is '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).

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

AG4/SG4/LR66/SR66/LR626/SR626/SR626SW Batteries Comparison 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
Amazon Link 376 377 SR626SW Battery Equivalent and Replacement

duracell 377 batteryNote: Amazon affiliate links open in the new windows, feel free to check them for the latest offers and prices.

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

- Alkaline LR/66LR626 batteries have nominal voltage 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 nominal voltage of 1.55 volts and it is rather constant over time as the battery is drained. Also, these batteries have larger capacity providing much longer longer operating time of various devices using single battery replacement.


For short: if you need AG4/SG4/LR66/SR66/LR626/SR626/SR626SW battery replacement for your wrist watch or similar electronic device, go for high quality SR626SW (376/377) battery and worry no more.