LR41, SR41, AG3, 392, and 312 Batteries and Their Equivalents
LR41, SR41, AG3, 392, and 312 batteries are non-rechargeable button/coin-cell batteries often used in calculators, thermometers, micro LED flashlights, toys, wearable electronics, and similar devices.
LR41, SR41, AG3, 392, and 312 differ not only in their labels, but also in chemistry - they all have similar, but different output voltages, capacities, discharge currents, and other characteristics, ensuring their use in different applications.
LR41, SR41, AG3, 392, and 312 Battery Features and Specifications
LR41, SR41, AG3, 392, and 312 are button/coin-cell batteries featuring physical dimensions of (D x H) 7.9 x 3.6 mm (~0.3110 x 0.1417 inches), while nominal capacity, nominal voltage, and other features depend on the actual battery chemistry.
Button/coin-cell 7.9 x 3.6 mm batteries are commonly labeled according to their chemistry, although some manufacturers use custom labels as well.
LR41 Alkaline Battery
Alkaline button/coin-cell 7.9 x 3.6 mm batteries are cheap and reliable, non-rechargeable batteries that feature a nominal voltage of 1.5 volts, a cutoff voltage of 0.9-1.0 volts, and a nominal capacity of 25-32 mAh, although there are brands that claim a capacity of up to 45 mAh.
Actual capacity significantly depends on the discharge current, age of the battery, and the temperature of the battery.
During discharge, the voltage of the alkaline LR41 batteries drops relatively quickly, thus LR41 batteries are recommended for devices that are not sensitive to the input voltage.
Although the most common label is LR41, other labels are used as well, including LR736 (IEC), AG3, L736, etc.
The shelf life of the LR41 batteries is relatively short - on average 2-3 years.
That is why LR41 batteries are very often replaced by compatible SR41 batteries.
SR41 Silver Oxide Battery
Silver-oxide button/coin-cell 7.9 x 3.6 mm batteries feature a nominal voltage of 1.55V, a cutoff voltage of 1.2V, and a nominal capacity in the 38-45 mAh range.
Silver-oxide batteries also feature much more stable voltage than alkaline batteries and are used for more sensitive devices, including analog and digital watches, measuring devices, calculators, and similar.
Self-discharge rate varies greatly, with some models having ~2% annual self-discharge rate (5-year shelf life), while other models have ~10% self-discharge rate (2-year shelf life).
Another important feature is discharge current - low-discharge SR41 batteries are intended for analog watches and digital watches that don't have alarms and LED lights, while high-drain SR41 batteries are intended for digital watches with alarms and LED lights, and for all other high-drain devices.
On the other hand, the self-discharge rate of the low-drain batteries is lower than the self-discharge rate of the high-drain batteries.
In order to simplify things, some manufacturers offer multi-drain SR41 batteries which combine the best of both worlds - high-drain currents and long shelf life. Such batteries are highly recommended for any device.
Note: Although the most common label is SR41, other labels are used as well, including SR41S, SR41W, SR41SW, SR736 (IEC), SG3, SR736W, SR736SW, 192, 384, 392, and similar.
312 Hearing Aid Battery
Zinc-air button/coin-cell 7.9 x 3.6 mm battery is a non-rechargeable battery mostly used for hearing aid devices.
The most common label of this battery is 312 battery, but other labels are used as well including PR41 (IEC), 7002ZD (ANSI), Brown Tab, ZA312, P312, and similar.
Zinc-air 7.9 x 3.6 mm battery features moist/gel electrolyte which is activated when a protective tab (brown in this case) is removed from the battery - air (oxygen) enters the battery, activating it within few minutes.
Most 312 batteries feature a shelf life of ~4 years at room temperature. When activated, their operating life is measured in weeks, at most - if the operating temperatures are higher and the air is drier, operating life may be at most 3-7 days.
312 batteries feature nominal voltage of 1.40-1.45 volts and cutoff voltage of 1.05-1.10 volts and typical capacity in the 180-185 mAh range, which is significantly more than the LR41/SR41 batteries' capacity.
Can 312 battery be replaced by SR41 battery? In theory, yes, if You don't have a zinc-air 312 battery, You can use an SR41 battery instead.
But, be aware that there is a large difference in capacity (~180 mAh vs ~45 mAh) between these two batteries. Also, zinc-air batteries are designed to provide stronger currents than SR41 batteries, which leads to an even larger capacity difference (when discharged by stronger currents, the actual capacity of SR41 batteries drops) and may lead to reliability issues.
312 hearing aid batteries may be easily ordered from online shops and with fast shipping, they can be at your doorstep within 24/48 hours (depending on your location and/or online store).
Rechargeable 312 Hearing Aid Batteries
Rechargeable 312 hearing aid batteries are 7.9 x 3.6 mm batteries featuring Nickel Metal Hydride (NiMH) chemistry or Silver Zinc (AgZn) chemistry.
NiMH 312 battery features a nominal voltage of 1.2 volts and capacity of 20-23 mAh and is capable of powering most hearing aid devices almost all day long - almost.
Another issue with the NiMH battery is its lower voltage (1.2 volts vs. 1.4 volts) when compared with the Zinc-Air battery that may cause certain devices to shut off too early.
Silver-zinc 312 battery features a nominal capacity of 40-45 mAh (twice of NiMH and very similar to SR41 battery) and is capable of powering almost all hearing aid devices all day long.
However, silver-zinc 312 batteries feature a nominal voltage of 1.8 volts and unless a hearing aid device is specifically designed to support both zinc-air (1.40-1.45V) and silver-zinc (1.8V) batteries, silver-zinc batteries should NOT be used in that particular hearing aid device.
LR41, SR41, 312 Battery Safety Issues
Modern LR41, SR41, 312 batteries don't contain mercury not other heavy metals or toxic pollutants. However, if they get swallowed by kids or pets, they can cause chemical burns due to various electrolytic processes in the body.
If LR41, SR41, 312 battery (or any similar battery) gets swallowed, call the emergency services right away and act according to their instructions.
Long Story Short: If You are looking for a button/coin-cell 7.9 x 3.6 mm non-rechargeable battery for your watch, thermometer, toy, remote, or any similar device, go for silver-oxide SR41 batteries from reputable brands that have many positive reviews - such batteries have been already tested by many users and they work well.
If You are looking for a non-rechargeable 312 hearing aid battery, good Brown Tab batteries should have a nominal capacity of at least 180 mAh and unactivated shelf life of at least 3-4 years.
Rechargeable 312 hearing aid batteries are available, but they are not used very much. Also, Silver-Zinc 312 batteries feature higher voltage and NOT all devices support such nominal voltage.