SR721SW/362 Battery Equivalent
SR721SW/362 battery is a small, button/coin-cell non-rechargeable battery, commonly used in wrist watches, credit card size devices, remote controllers, calculators, medical instruments, and similar.
SR721SW/362 is a silver-oxide battery, having a long shelf life, good tolerance to pulse currents, a wide operating temperature range, etc. Alkaline batteries with the same dimensions are also manufactured, but they feature shorter shelf life, smaller capacity, and similar, but they are somewhat cheaper.
Published: September 30, 2021.
SR721SW/362 Battery Features and Specifications
SR721SW/362 battery is a silver-oxide button/coin cell battery with physical dimensions of 7.9 x 2.1 mm (~0.3110 x 0.0826 inches), with a nominal voltage of 1.55V, a cutoff voltage of 1.2 volts, and a nominal capacity of 25-30 mAh.
Note: nominal capacity depends on the drain current, battery age, temperature, and similar.
SR721SW/362 battery feature a self-discharge rate of 5-10% per year, depending on the battery model, although the self-discharge rate depends on the storage temperature as well.
Most SR721SW/362 batteries feature operating temperatures from 0°C to +60°C, with some models supporting an even wider operating temperature range.
SR721SW/362 batteries feature other labels as well, including SR721, SR721W, SR721PW, SR58, 162, 361, 362, SG11, AG11, D361/D362, and similar.
Note: labels are often used interchangeably, but:
- SR721 is a general-purpose silver-oxide 7.9x2.1 mm battery,
- SR721S is a silver-oxide 7.9x2.1 mm battery with sodium hydroxide electrolyte,
- SR721P is a silver-oxide 7.9x2.1 mm battery with potassium hydroxide electrolyte,
- SR721W is a silver-oxide 7.9x2.1 mm battery intended for watches, etc.
Thus, SR721SW would be a silver-oxide 7.9x2.1 mm battery with sodium hydroxide electrolyte, intended for watches.
Some silver-oxide SR721/SR721SW batteries are designed as low-discharge batteries (also labeled as 362 batteries), while other SR721/SR721SW batteries are designed as high-discharge batteries (also labeled as 361 batteries).
But, some manufacturers also offer multi-drain SR721/SR721SW batteries, commonly labeled as 361/362 batteries, but also using other labels as well.
The following comparison chart lists some of the most popular silver-oxide 7.9x2.1mm batteries with their most important features and specifications:
|Capacity||Operating Temperature||Annual Self-Discharge Rate||Discharge Current|
|Duracell D361/D362||24 mAh, 47 kΩ down to 1.2V @20°C||0°C to +60°C||<10% @20°C||44.5 μA, 34k8Ω @20°C
(Note: datasheet → 47kΩ?!)
|muRata SR721||29 mAh, 30 kΩ down to 1.2V @23°C||-10°C to +60°C||-||50 μA, 30 kΩ @23°C|
|Renata 361||24 mAh, 34k8Ω down to 1.2V @20°C||-10°C to +60°C||<10% @20°C||44.5 μA, 34k8Ω @20°C|
|Renata 362||23 mAh, 34k8Ω down to 0.9V @20°C||-10°C to +60°C||<5% @20°C||45 μA, 34k8Ω @20°C|
Note: Duracell D361/D362 battery datasheet specifies a standard discharge current of 44.5 μA over 47 kΩ load, but that is impossible for a 1.55V battery. After some math, we have calculated that the required load for such current is 34k8Ω (34.8 kΩ), just as the load used for Renata 361 and 362 batteries.
Alkaline 7.9x2.1 mm batteries are non-rechargeable batteries featuring a nominal voltage of 1.5V, a cutoff voltage of 0.9V and a nominal capacity of 15-25 mAh, depending on the battery age, temperature, and discharge conditions.
Alkaline 7.9x2.1 mm batteries are usually labeled as LR721, LR58, or AG11 batteries, although some manufacturers still use other labels as well.
When compared with the silver-oxide 7.9x2.1 mm batteries, alkaline 7.9x2.1 mm batteries are somewhat cheaper but have a smaller capacity, less stable output voltage, shorter shelf-life, and similar.
Nonetheless, high-quality alkaline LR721 batteries are commonly used in micro-LED flashlights and toys, medical instruments, calculators, and similar.
SR721SW/362 Battery Safety Issues
Modern SR721SW/362 batteries don't contain heavy elements like lead, mercury, cadmium, and similar and are environment friendly.
But, when they die, they must be recycled properly.
Also, if the SR721SW/362 batteries get swallowed by pets or kids, contact the nearest emergency center and explain what happened and act according to their instructions.
Small batteries can be rather dangerous - despite not having toxic metals, if they get swallowed, they can cause electrolysis which can cause very dangerous internal burns...
So, keep SR721SW/362 and other batteries away from kids and pets.
Long Story Short: If You are looking for a new 7.9x2.1 mm non-rechargeable battery, go for silver-oxide SR721SW/362 multi-drain batteries - such batteries have stable output voltage, good capacity, tolerate surge discharges well, have low self-discharge rate, etc.