SR616SW/321 Battery Equivalents and Replacements
SR616SW/321 are button/coin-cell batteries, commonly used in wrist watches, PDAs, calculators, credit card size devices, and other low-drain, continuous operation devices.
SR616SW/321 are fairly popular batteries, almost always available at hardware stores and online shops. However, many manufacturers use their own labels, leading to confusion regarding these batteries.
SR616SW/321 Battery Dimensions, Specifications, and Features
SR616SW/321 batteries are button/con-cell batteries featuring physical dimensions (D x H) of 6.8 x 1.65 mm (0.2677 x 0.065 inches) and they weigh ~0.25 grams (~0.009 ounces).
SR616SW/321 batteries are commonly made using silver-oxide chemistry, although some brands make cheaper alkaline batteries.
Silver-oxide batteries are usually labeled as SR65, SR616, SR616W, SR616SW, 321, V321, E321, D321, and similar, they feature shelf life of 3-7 years, with some models having a shelf life of up to 10 years. The nominal voltage of silver-oxide SR616SW/321 batteries is 1.55 volts and is rather stable during use.
Cut-off voltage and capacity of silver oxide SR616SW/321 batteries depends on the cut-off voltage of the powered device and drain current, and is ~1.2 volts and 13-15 mAh.
Because of all these reasons, silver-oxide SR616SW/321 batteries are commonly required for Swatch, Fossil, Timex, Casio, and other popular watch brands.
Alkaline 6.8x1.65 mm batteries are usually labeled as LR65, they feature a nominal voltage of 1.5 volts that quickly drops down to 0.9 - 1.0 volts. Also, their capacity is lower.
Although alkaline LR65 batteries are somewhat cheaper than silver-oxide SR616SW/321 batteries, the price difference is almost negligible, especially considering the advantages of silver-oxide chemistry.
That is why silver-oxide SR616SW/321 batteries are much more common, with many battery brands not even manufacturing alkaline LR65 batteries.
SR616SW/321 Batteries Safety Issues
Most modern SR616SW/321 batteries do NOT contain mercury, cadmium, and similar heavy metals and other dangerous and poisonous pollutants.
However, SR616SW/321 batteries are very small and shiny items that may be swallowed by pets and kids - that is why most brands package their SR616SW/321 batteries using so-called 'pets and kids safe packages'.
But, if SR616SW/321 batteries get swallowed, they may cause heavy internal injuries and burns due to the electrolysis.
Although their capacity is limited (13-15 mAh) and they can't cause as heavy injuries as larger batteries with much higher capacity, if SR616SW/321 batteries get swallowed call local emergency center and act according to their instruction.
Long Story Short: If You are looking for a button/coin-cell 6.8x1.65 mm battery, go for silver-oxide battery labeled as SR65, SR616, SR616W, SR616SW, 321, V321, E321, D321 or similar, from reputable brands.
Such batteries are by default used by many popular watch brands including Swatch, Fossil, Casio, Timex, etc.