SR41 and LR41 Battery Equivalents and Replacements
SR41 and LR41 batteries are small, button/coin cell batteries often used in digital thermometers, wrist watches, toys, small LED flashlights, wearable electronics, remote controls, and similar devices.
These batteries are available on the market in several chemistries, featuring similar, but not the same discharge characteristics and are often labeled differently by their manufacturers, leading to some confusion by their users.
Physical dimensions of SR41 and LR41 batteries are (D x H) 7.9 x 3.6 mm (0.311 x 0.142 inches) with their common features given in the following cross reference chart:
|Nominal Voltage||1.5V||1.55V||1.4 - 1.45V|
|Notes||Voltage drops over time||Very constant voltage||Slightly lower voltage, large capacity;
mostly used as hearing aid batteries
|Typical Labels||LR41, LR736, AG3||SR41, SR736, SR736PW, SR736SW, SG3, AG3, 192, 384, 392||312, ZA312, Brown Tab, PR41, 7002ZD|
|Typical Capacity||25-32 mAh||38-45 mAh||~160 mAh|
The actual capacity of these batteries depends on the cutoff voltage of the device, but it also depends on the drain current - the stronger the current, the lower the end capacity will be.
Alkaline 7.9 x 3.6 mm batteries: Most common label for alkaline 7.9 x 3.6 mm battery is LR41 battery, although other labels are used as well, like LR736, AG3, and similar.
Fortunately, most reputable brands always use LR41 as part of the battery label, allowing the users to easily determine the battery type and model.
LR41 battery features a nominal voltage of 1.5 volts and a nominal capacity of 25-32 mAh. Some brands claim much larger capacity of their LR41 batteries, but such batteries are often drained using ultra-low currents, with their actual capacities being often within 25-32 mAh range.
The cutoff voltage of the LR41 battery depends on the cutoff voltage of the device being powered, but it is mostly around 1.0 volts, although there are many simple devices being able to operate even at 0.8 volts per battery.
Note: LR41 batteries are very popular batteries, often used, for example, as digital thermometer batteries. If the thermometer says 'LO' or 'LOW' that means that the measured temperature is below a certain threshold, not that the battery is (almost) dead - just to be sure, always check the thermometer's manual!
The shelf life of the LR41 batteries depends on the storage temperature and brand, but if the batteries are kept at or below 68-77°F (20-25°C), the expected shelf life should be at least 2-3 years.
Silver-oxide 7.9 x 3.6 mm batteries: Most common label for silver-oxide 7.9 x 3.6 mm battery is SR41 battery, although other labels are used as well, like SR736, SR736PW, SR736SW, SG3, AG3, 192, 384, 392, and similar.
SR41 battery features a nominal voltage of 1.55 volts and a nominal capacity of 38-45 mAh.
The output voltage of the silver-oxide batteries is more stable than the voltage of alkaline batteries, thus, making them a preferred choice for powering more sensitive devices like wrist watches and similar.
The cutoff voltage of the SR41 battery also depends on the cutoff voltage of the device being powered, but it is mostly around 1.2 volts - when the voltage of the silver-oxide battery drops down to ~1.25 volts and especially down to 1.2 volts, it starts to drop sharply.
Silver-oxide SR41 batteries were often built as low-drain and high-drain batteries, with low-drain SR41 batteries being intended for watches and similar devices that operate constantly using very low currents, and high-drain SR41 batteries being intended for devices that periodically require relatively high currents.
With the advances in technology, most modern SR41 batteries are designed as multi-drain batteries.
For example, Energizer 392/384 battery (external link, PDF datasheet) features a nominal voltage of 1.55 volts and 44 mAh typical capacity when being drained using 22 kΩ load, at 21°C, down to 1.2 volts.
Silver-oxide SR41 batteries feature longer shelf life than alkaline LR41 batteries - when stored at 68°F (20°C), the expected shelf life of a good SR41 battery is in the 6-8 year range, sometimes even more.
Zinc Air 7.9 x 3.6 mm batteries: zinc-air batteries feature a much larger capacity than the alkaline or silver-oxide batteries and is usually around 160 mAh, with a nominal voltage around 1.45 volts and the cutoff voltage around 1.1 volts.
Most common labels of zinc-air 7.9x3.6 mm batteries are 312, ZA312, Brown Tab, PR41, 7002ZD, etc.
Brown Tab zinc-air batteries are used almost exclusively as a hearing aid batteries.
When the protective tab is removed, air (oxygen!) enters the battery where reactions start quickly - after removing the protective tab, it is usually enough to wait a minute or two, before the battery is ready to be used.
Since zinc-air batteries use wet/moist electrolyte, their operating time after the protective tab is removed is limited to several weeks, rarely more - this depends on the local temperature mostly.
SR41, LR41, Brown Tab Batteries Security Issues
While modern SR41, LR41, and Brown Tab batteries are free of mercury and other heavy metals, and as such, they are not toxic, if SR41, LR41, Brown Tab batteries are swallowed by a kid or a pet, they may cause chemical burns and internal injuries due to the electrolytic processes they may cause within the body.
Because of that danger, most SR41, LR41, Brown Tab batteries are packed in so-called 'Pet/Kid-safe packages'.
However, if something like that happens, be sure to contact the nearest emergency center (or call a doctor or a vet) and follow their instructions.
Long Story Short: SR41, LR41 and PR41 batteries are very popular batteries, available at most hardware and online shops.
If You are unsure about which brand and model, always go for a popular battery models from a reputable brands that have been used by countless users in many real-life situations.