397/396 Watch Battery Equivalents and Replacements
397/396 watch batteries, also known as SG2, SR59, SR726, or SR726SW batteries, are small, non-rechargeable 1.55V batteries based on the silver-oxide battery chemistry.
These button/coin cells feature very stable output voltage and are used in measuring devices that benefit from such power sources, including watches, medical instruments, sporting goods, etc.
Published: May 23, 2023.
397/396 Batteries Features and Specifications
397/396 batteries are button/coin cell batteries with physical dimensions of 7.9 x 2.6 mm (~0.31102 x 0.10236 inches).
Non-rechargeable 7.9 x 2.6 mm batteries generally can be found in two chemistries:
- Alkaline 7.9 x 2.6 mm batteries, with typical labels of LR59, LR726, AG2, and similar, with a nominal voltage of 1.5V, a cutoff voltage of 0.8-0.9V, and a capacity of 23-27 mAh.
- Silver-oxide 7.9 x 2.6 mm batteries, with typical labels of SR59, SR726, SR726SW, SG2, 397, 396, 397/396, and similar, with a nominal voltage of 1.55V, a cutoff voltage of 1.2-1.3V and a capacity of 32-35 mAh.
Also, silver-oxide batteries feature a much more stable output voltage and lower self-discharge rate, making alkaline batteries very rare in this size - 7.9 x 2.6 mm batteries are almost exclusively used for watches and other similar devices, making silver-oxide a preferred choice for both manufacturers and consumers.
397 Battery vs. 396 Battery
Both 397 batteries and 396 batteries are silver-oxide 7.9 x 2.6 mm batteries, but the 397 battery is considered as "low-drain" battery, and the 396 battery is considered as "high-drain" battery.
Thanks to technological advancements, many brands now offer 397/396 multi-drain batteries, often simply labeled as LR726SW batteries.
397, 396, SR726SW Batteries Cross Reference Chart
The following cross-reference chart lists some of the silver-oxide 7.9 x 2.6 mm batteries with their most important features and specifications:
|Capacity||Operating Temperature||Annual Self-Discharge Rate||Discharge Current|
|Duracell D396/D397||32 mAh over 33kΩ down to 1.2V @20°C||0°C to +60°C||≤10% @20°C||60.7μA over 33kΩ @20°C|
|Energizer 397/396||33 mAh over 45kΩ down to 1.2V @21°C||-||~2% @20°C||34μA @1.53V over 45kΩ @21°C|
|Energizer 397||32 mAh over 45kΩ down to 1.3V @21°C||-||-||34μA @1.55V over 45kΩ @21°C|
|Energizer 396||32 mAh over 45kΩ down to 1.3V @21°C||-||-||34μA @1.55V over 45kΩ @21°C|
|Renata 396 High Drain||32 mAh over 25.5kΩ down to 1.2V @20°C||-10°C to +60°C||≤10% @20°C||61.9μA over 25.5kΩ @20°C|
|Renata 397 Low Drain||32 mAh over 25.5kΩ down to 1.2V @20°C||-10°C to +60°C||≤5% @20°C||60.7μA over 25.5kΩ @20°C|
|Seiko SR726SW||34mAh over 25.5kΩ down to 1.2V @23°C||-10°C to +60°C||-||40μA std. cont.|
As one can see, a typical 397, 396, SR726SW battery has a shelf life of 2-5 years, an operating temperature range of at least 0°C to 50-60°C, and a nominal capacity of ≥30mAh.
Note: actual capacity depends on the battery age and model, discharge current, temperature, etc.
Of course, other 397/396/SR726SW battery brands on the market also offer very good batteries - just be sure to check the manufacturing date, if possible, before buying.
397, 396, SR726SW Battery Frequently Asked Questions
Here are some of the most popular Frequently Asked Questions about these batteries.
What battery is equivalent to 397?
Any silver-oxide 7.9 x 2.6 mm battery with a nominal voltage of 1.55V can be used to replace the 397 battery. These batteries include 396 batteries, SG2 batteries, LR726SW batteries, etc.
What battery is equivalent to 396?
Since 396 batteries are high-drain batteries, they should not be replaced with low-drain 397 batteries but can be replaced using multi-drain 397/396 and LR726SW batteries.
Are 396 and 397 batteries the same?
No, they are not. Although 396 and 397 batteries share the chemistry, 396 is optimized for high-drain applications, and 397 is optimized for low-drain applications.
396 batteries can be used to replace 397 batteries; just be aware that most 397 batteries feature a lower self-discharge rate than 396 batteries.
What size is a 397 battery?
397 battery feature physical dimensions of (D x H) 7.9 x 2.6 mm.
What is a Duracell 397 equivalent to?
Duracell 397 battery, often labeled as a D397 battery (or D397/D396 battery), is equivalent to any low-drain 397 battery or multi-drain 397/396 or LR726SW battery.
Can you mix two different batteries, for example, LR726 and SR726SW?
No, one should not mix batteries featuring different chemistries - that battery pack will not last for a long time. Also, due to the presence of alkaline battery or batteries, the output voltage would drop quickly.
In short, no, don't do it.
Few Final Words
Button/coin cells featuring silver-oxide chemistry and physical dimensions of 7.9 x 2.6 mm are often labeled as SR726SW, 397, 396, SG2, 397/396, etc., and are used for accurate measurement devices, including watches, sporting goods, and medical instruments.
They can easily be found at online stores or sometimes in local hardware and office supplies stores.
When buying 7.9 x 2.6 mm batteries, go for models from reputable brands with good reviews, for example (Amazon links; the links open in the new windows):
Personally, alkaline 7.9 x 2.6 mm batteries tend to be a little bit cheaper, but silver-oxide batteries, with their better performances, more than justify the price difference.