LR521, LR63, SR521, SR521S, SR521SW, SR63, 379, SG0, AG0 Battery Equivalents and Replacements
LR521, SR521, 379, AG0 button cell batteries are often used in wrist watches, toys, remotes, and similar low drain devices. These batteries are manufactured by most, if not all, most reputable battery brands and are easy to find, if you know what to look for.
LR521, SR521, AG0 button cell battery dimensions are: diameter 5.8 mm and height 2.1 mm.
Like most of similar button cell batteries, LR521, SR521, AG0 batteries feature two main chemistries:
- Alkaline batteries are commonly labeled as LR512, LR63, AG0, 379 and similar - they are recognizable thanks to the 'LR' or 'AG' prefixes, although some manufacturers use numbers only labels, but also describe the battery chemistry on the package of the battery.
Nominal voltage of LR63/LR512/AG0 batteries is 1.5 volts, but as the battery is used, voltage drops. Cut-off voltage depends on the device used, but generally it is around 1.0 volts.
Typical capacity of alkaline 379 battery is around 10 mAh, also depending on the common temperature, drain current, battery age and similar.
- Silver-oxide batteries are commonly labeled as SR521, SR521, SR521SW, SR63, 379, SG0 and similar. These batteries differ from alkaline batteries by mostly having prefix 'SR', although some brands use 'numbers only' labels and similar. In order to attract potential customers, most of the brands write down the labels of the models that their batteries actual replace.
Of course, this sometimes increase the confusion which battery to buy, but generally greatly simplifies finding proper battery replacement.
Nominal voltage of SR521, SR521, SR521SW, SR63, 379, SG0 batteries is 1.55 volts and typical capacity is in 16-18 mAh range, which is significantly more than alkaline typical capacity of 10 mAh.
Cut-off voltage of silver-oxide batteries is ~1.2 volts, but this also depends on the cut-off voltage of the device in use. In any case, silver-oxide batteries have much more stable voltage than alkaline batteries.
Long Story Short: if you need button cell battery 5.8 mm in diameter and 2.1 mm in height and you are not sure which one to get, follow these rules:
- LR521, LR63, AG0 and similar are alkaline batteries: cheaper, but also less stable voltage and lower capacity,
- SR521, SR521S, SR521SW, SR63, 379, SG0 and similar are silver-oxide batteries: they slightly cost more, but have more stable voltage and higher capacity. If you have wrist watch or any similar electronic device, be sure to get battery that is labeled SR521SW. Personally, the price difference between alkaline and silver oxide batteries is very low and IMHO justifies buying silver-oxide batteries.