The prefix before the number denotes the chemical composition of the battery.

• BR/CR denotes lithium chemistry
• L shows an alkaline composition
• SR represents silver oxide
• LR means alkaline
• SG stands for silver oxide
• AG is another prefix for alkaline batteries

Note: Manufacturers who denote silver oxide batteries with SR will also use LR for alkaline cells. Those using SG for silver oxide also use AG for alkaline. 

 

Silver oxide cells are grouped into high drain or low drain.

• The suffix ¨SW¨ at the end of the reference number is used to denote low drain applications.
• The suffix ¨W¨shows cells that can be used in high drain devices.

 

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Duracell Technical Library

https://www.duracell.com/en-us/techlibrary/product-technical-data-sheets/

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ENERGIZER L91    (3000 mah)

https://data.energizer.com/pdfs/l91.pdf

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 LR626 vs. SR626 Batteries Comparison Chart

Comparison and examples of alkaline and silver-oxide 6.8 x 2.6 mm coin-cell 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	LR66, LR626, AG4	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 LR66/LR626 batteries have a nominal voltage of 1.5 volts, and it relatively quickly drops over time down to 1.0 volts.

Since 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, digital watches without alarms and LEDs, thermometers, and similar.

But, most manufacturers today offer so-called multi-drain 376/377 (SR626SW) batteries, suitable for both digital and analog watches, toys, thermometers, keychain LED flashlights, and similar devices.

SR626SW, 377, 376 Batteries Comparison Chart

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

Battery Datasheet	Chemistry Nominal and Cutoff Voltages	Capacity Discharge Current	Operating Temperature Annual Self-Discharge Rate
Duracell D377/376	Silver Oxide 1.55V/1.2V	24 mAh, 47kΩ down to 1.2V @20°C 44.8μA @1.54V @20°C	0°C to +60°C <10% @20°C
Energizer 377/376	Silver Oxide 1.55V/1.2V	24 mAh, 47kΩ down to 1.2V @21°C 31μA @1.46V 47kΩ @21°C	– ~2% @20°C
muRata SR626	Silver Oxide 1.55V/1.2V	28 mAh, 30kΩ down to 1.2V @23°C 50μA @1.55V 30kΩ @23°C	-10°C to +60°C –
Renata 376 High Drain	Silver Oxide 1.55V/1.2V	27 mAh, 34k8Ω down to 1.2V @20°C 44.5μA @1.55V 34k8Ω @20°C	-10°C to +60°C  <10% @20°C
Renata 377 Low Drain	Silver Oxide 1.55V/1.2V	24 mAh, 34k8Ω down to 0.9V @20°C 43.7μA @1.55V 34k8Ω @20°C	-10°C to +60°C <5% @20°C
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

 

Sources:
https://batteryspecialists.com.au/blogs/news/3-ag3-battery-equivalents-when-you-cant-find-ag3s

https://www.batteryequivalents.com/ag4-lr626-376-377-sr626-sr626sw-battery-equivalents.html#:~:text=The%20proper%20label%20of%20the,,%20and%20376%2F377%20battery.