---
title: "SR521SW equivalent: 379, SR63, SR521"
description: "The SR521SW is a 1.55 V silver oxide cell, also sold as 379, SR63, SR521. Full equivalents, what does not substitute, and where it is used."
url: https://atoneplace.net/battery/sr521sw/
site: "At One Place"
---

# SR521SW battery

**What replaces a SR521SW: 379, SR63, SR521, SR521W, AG0, D379**

1.55 V silver oxide, 5.8 × 2.1 mm (diameter × height)

The SR521SW is a single-use 1.55 V silver oxide button cell. The codes below are the same physical cell sold under different manufacturer names, and any of them will fit.

## Specification

- **IEC designation:** SR521SW
- **ANSI / NEDA:** 1191SO
- **Nominal voltage:** 1.55 V
- **Chemistry:** Silver oxide
- **Size:** 5.8 × 2.1 mm (diameter × height)
- **Typical capacity:** 14.5 mAh
- **Rechargeable:** No — never charge it

## Codes that mean the same battery

*Different manufacturers, one physical battery. Voltage, chemistry and dimensions all match.*

| Code | Fits? |
| --- | --- |
| 379 | Yes — same cell |
| SR63 | Yes — same cell |
| SR521 | Yes — same cell |
| SR521W | Yes — same cell |
| AG0 | Yes — same cell |
| D379 | Yes — same cell |
| V379 | Yes — same cell |
| 1191SO | Yes — same cell |
| SB-AJ | Yes — same cell |

## Codes that look close but are not

| Code | Why it is not a substitute |
| --- | --- |
| SR527SW / 319 | Same 5.8 mm diameter, 2.7 mm tall. Too tall for a 379 case. |

> The SR521SW is a primary cell and must never be put in a charger. Charging a sealed primary battery builds gas pressure inside a can with no vent designed for it, which is how they rupture or catch fire. Rechargeable look-alikes exist for several sizes and carry different codes — check the code, not the shape.

## Where it turns up

- Very small ladies' watches
- Slim fashion watches
- Miniature LED lights
- Small electronic jewellery

## Common questions

### What is equivalent to a SR521SW?

379, SR63, SR521, SR521W, AG0, D379, V379, 1191SO, SB-AJ — all the same 1.55 V cell under different manufacturer codes.

### Can I use a SR527SW / 319 instead of a SR521SW?

Same 5.8 mm diameter, 2.7 mm tall. Too tall for a 379 case.

### Is the SR521SW rechargeable?

No. It is a primary cell — charging one risks rupture or fire. Rechargeable look-alikes exist in the same size under different codes.

## Related pages

- [LR44 battery](https://atoneplace.net/battery/lr44/)
- [SR626SW battery](https://atoneplace.net/battery/sr626sw/)
- [SR44 battery](https://atoneplace.net/battery/sr44/)
- [PR41 battery](https://atoneplace.net/battery/za312/)
- [PR48 battery](https://atoneplace.net/battery/za13/)
- [SR621SW battery](https://atoneplace.net/battery/sr621sw/)
- [PR44 battery](https://atoneplace.net/battery/za675/)
- [SR920SW battery](https://atoneplace.net/battery/sr920sw/)
- [LR41 battery](https://atoneplace.net/battery/lr41/)
- [PR70 battery](https://atoneplace.net/battery/za10/)
- [SR927SW battery](https://atoneplace.net/battery/sr927sw/)
- [LR1130 battery](https://atoneplace.net/battery/lr1130/)

## Sources

- Official vendor product documentation — At One Place (/about/)