TIANQIUSeiko Watch Battery
Seiko Watch Battery Codes
Seiko prints its own battery code (SB-… ) on the cell and in its service documentation, and that code maps onto a standard silver-oxide cell. We supply the correct watch battery factory direct, with custom label & bulk for watch brands.
Seiko prints its own battery code (SB-… ) on the cell and in its service documentation, and that code maps onto a standard silver-oxide cell. The seiko's own battery codes listed below — 19 of them — are each mapped to the standard silver-oxide cell of the same size, with the manufacturer source shown for every row.
Battery Type
The cell we supply as standard: 377
Dimensional drawing — cell photo on request
377 Specifications
| Model | 377 |
|---|---|
| Chemistry | Silver Oxide |
| Voltage | 1.55V |
| Diameter | 6.8mm |
| Thickness | 2.6mm |
| Capacity | 24mAh |
| Equivalent to | 377 = SR626SW = SR626 = 376 |
Equivalent to 377 = SR626SW = SR626 = 376. See the full cross-reference table. A steady 1.55V silver-oxide cell is the correct choice for a watch movement.
Capacity: 24mAh · Thickness: 2.6mm.
Cross Reference
Seiko's own battery codes — what standard cell does each one map to?
Seiko does not publish a public movement-to-battery lookup, so we are not going to guess which cell your particular watch takes. What is documented — and what you can act on — is Seiko's own code system: the SB-… code printed on the old cell maps onto a standard silver-oxide cell. Read the code off your old cell or the caseback, find it below, and you have the cell.
| Seiko code | Standard cell | Size | Source |
|---|---|---|---|
| SB-AU | 390 / SR1130SW | 11.6 × 3.05 mm | Maxell · Renata |
| SB-BU | 389 / SR1130W | 11.6 × 3.05 mm | Maxell — single source, treat as unconfirmed |
| SB-B9 | 357 / SR44W | 11.6 × 5.4 mm | Maxell · Renata |
| SB-A9 | 303 / SR44SW | 11.6 × 5.4 mm | Maxell — single source, treat as unconfirmed |
| SB-B8 | 386 / SR43W | 11.6 × 4.2 mm | Maxell — single source, treat as unconfirmed |
| SB-A8 | 301 / SR43SW | 11.6 × 4.2 mm | Maxell — single source, treat as unconfirmed |
| SB-AW | 377 / SR626SW | 6.8 × 2.6 mm | Maxell · Duracell (SB-AW) — cross-confirmed |
| SB-BW | 376 / SR626W | 6.8 × 2.6 mm | Maxell — single source, treat as unconfirmed |
| SB-AG | 364 / SR621SW | 6.8 × 2.15 mm | Maxell — single source, treat as unconfirmed |
| SB-AN | 371 / SR920SW | 9.5 × 2.05 mm | Maxell — single source, treat as unconfirmed |
| SB-BN | 370 / SR920W | 9.5 × 2.05 mm | Maxell — single source, treat as unconfirmed |
| SB-AP | 395 / SR927SW | 9.5 × 2.73 mm | Maxell — single source, treat as unconfirmed |
| SB-A4 | 394 / SR936SW | 9.5 × 3.6 mm | Maxell — single source, treat as unconfirmed |
| SB-A1 | 384 / SR41SW | 7.9 × 3.6 mm | Maxell — single source, treat as unconfirmed |
| SB-B1 | 392 / SR41W | 7.9 × 3.6 mm | Maxell — single source, treat as unconfirmed |
| SB-AK | 362 / SR721SW | 7.9 × 2.1 mm | Maxell — single source, treat as unconfirmed |
| SB-AL | 397 / SR726SW | 7.9 × 2.6 mm | Maxell — single source, treat as unconfirmed |
| SB-AC | 379 / SR521SW | 5.8 × 2.15 mm | Maxell · Renata |
| SB-AR | 317 / SR516SW | 5.8 × 1.65 mm | Maxell — single source, treat as unconfirmed |
Source: Maxell Micro Battery Cross Reference and Replacement Guide (SEIKO column) · Renata product pages. Every row above comes from a manufacturer-authored cross-reference table. Where a Seiko code appears in only one manufacturer's material it is marked single source — we have not filled those gaps by inference. If your code is not listed, send us the code and the movement number and we will confirm the cell against the datasheet.
How-To
How to Replace a Seiko Watch Battery
- Open the watch case back with a watch-back tool or flat screwdriver
- Note the battery size and which side faces up
- Remove the old 377 cell with non-metallic tweezers
- Insert a fresh 377 battery with the correct polarity
- Re-seal the case and set the time
Match the exact size and voltage. A wrong-thickness cell can jam the case back or power the watch incorrectly.
Watch Batteries
Which other watch battery models are there?
Size Guide
How do I find the right watch battery size?
A watch cell is identified by diameter and thickness together — the IEC type number encodes both. Read the marking on your old cell and match it below; if the marking has worn away, measure the cell and pick the row that matches. These are the silver-oxide watch cells we manufacture.
| Model | Voltage | Diameter | Thickness | Capacity | Also marked |
|---|---|---|---|---|---|
| SR626 | 1.55V | 6.8mm | 2.6mm | 27mAh | SR626SW · 377 · 376 |
| 377 | 1.55V | 6.8mm | 2.6mm | 24mAh | SR626SW · SR626 · 376 |
| 364 | 1.55V | 6.8mm | 2.1mm | 18mAh | SR621SW · AG1 |
| 371 | 1.55V | 9.5mm | 2.1mm | 38mAh | SR920SW · 370 |
| SR44 | 1.55V | 11.6mm | 5.4mm | 175mAh | SR44W · 357 · 303 |
Fit is decided by size and voltage, not by brand — that is why the same cell carries several trade numbers (377 = SR626SW = AG4 = SG4). Match on diameter and thickness and the cell will seat correctly.
Guide
How to Replace a Watch Battery (Tools, Sizes and Steps)A watch battery change needs the right cell, a case-back tool and a clean bench. Step-by-step, plus the watch cell sizes we make.
FAQ
What do buyers ask about Seiko watch batteries?
What battery does a Seiko watch use?
Seiko does not publish a public movement-to-battery lookup that we could verify, so we will not state which cell a particular Seiko model takes. What is documented is Seiko's own code for the cell: read that code off the old cell or the caseback and match it in the table on this page — the code maps onto a standard silver-oxide cell.
How do I replace a Seiko watch battery?
Pry the case back open with a watch-back tool, note the battery polarity, remove the old cell with non-metallic tweezers, insert the new battery (correct side up) and re-seal the case.
Is the 377 battery rechargeable?
No — the standard 377 is a primary (non-rechargeable) Silver Oxide cell. Replace it rather than recharge.
How do I check which watch battery size I need?
Read the code on the old cell first — Seiko prints its own code on the cell (SB-AU, SB-BU, SB-B9, SB-A9, …) and that code maps onto a standard cell in the table on this page. If the print has worn off, measure the old cell: diameter and thickness together identify the model.
What do the numbers on a watch battery mean?
The IEC type number encodes the size, not the brand. In SR626SW the code gives a 6.8mm diameter and 2.6mm thickness at 1.55V. Trade numbers point at the same cell — 377 = SR626SW = SR626 = 376 — so any of those markings is a direct replacement for the other.
Does it matter which watch battery brand I buy?
Fit is set by the model number, not the brand: any cell matching the size and voltage fits the holder. What does vary is the capacity and the consistency of the discharge curve, which is why we publish 24mAh for the cell we supply and can send the discharge data with a quote.
How do I buy 377 watch batteries in bulk?
Factory-direct 377 cells with OEM custom label. Get a quote today.