Renata 377 SR626SW Watch Battery Review – Are These the Right Replacement Cells?

Quick Verdict

The Renata 377 SR626SW silver oxide watch battery is the real deal — a genuine Swiss-made button cell that watchmakers actually trust. I picked up a 3-pack to replace the failing cell in my wife's two-year-old Fossil and ended up using the spare on a bathroom scale that had been running slow. At the time of writing the Renata 377 is available on Amazon in a 3-cell strip, and it earns a solid 4.4 out of 5 — not because it is flashy, but because it does exactly what a watch battery should do: delivers clean, stable voltage until it dies. If you need a 377 or SR626SW replacement, keep reading.

What Is the Renata 377 Watch Battery?

The Renata 377 is a small-format silver oxide button cell, 6.8 mm in diameter and roughly 2.6 mm tall — you have almost certainly held one without realising it. It operates at 1.55 V nominal and is cross-referenced under the industry-standard designation SR626SW (you will also see it listed as AG4, SG66, or simply 377 depending on the brand). Renata, a Swiss company with decades of experience producing precision cells for the watch and medical-device industries, supplies these directly to OEM manufacturers, which means the version you buy in a retail 3-pack is the same cell a technician would install at a service centre.

Key Features

• Voltage: 1.55V nominal — the correct specification for the vast majority of 377/SR626SW-powered devices
• Chemistry: Silver oxide — steadier discharge curve than alkaline equivalents, which matters enormously in timepieces
• Cross-reference compatibility: SR626SW, 377, SR66, AG4, SG66 — covers most naming conventions used by manufacturers
• Renata OEM pedigree — the same brand many watchmakers specify for authorised replacements
• Low self-discharge — cells can sit in storage for 12 months or more without significant capacity loss
• 3-pack format — practical for anyone maintaining more than one small device
• Leak-resistant construction when stored within normal temperature and humidity ranges

Hands-On Review

The morning I opened the envelope from Amazon, I set the Renata 377 cells next to the old Fossil on my kitchen counter. The packaging is straightforward — a heat-sealed plastic strip holding all three cells — and the cells themselves have a reassuring weight to them. Not heavy, exactly, but you can feel the solidity compared to the generic alkalines you sometimes find bundled with cheap novelty watches.

Installing the Renata 377 took about ninety seconds with a basic case-back tool. The moment the new cell dropped into the compartment, the second hand jumped to life — clean, immediate, no hesitation. I set the time, fastened the case back, and that was it. By day three I had stopped thinking about it entirely, which honestly is the best sign a watch battery can give you.

What surprised me was how confidently the Renata cell sat in the compartment. Some budget cells I have used in the past have a slight rattle even when the retainer clip is in place — not the case here. The tolerances feel tight and deliberate. After three weeks of daily wear the watch has not drifted by more than a few seconds, which is completely normal for a quartz movement.

Will I keep using Renata 377 cells in every watch I own? Probably — with one caveat. If a device draws more than the typical watch movement (say, a backlit digital gadget running continuously), you may find the capacity a little thin. For standard timepieces and low-drain electronics, though, it is extremely hard to beat.

Who Should Buy It?

• Watch collectors and repair enthusiasts who need reliable replacement cells for multiple timepieces and want a name they can trust
• Anyone whose Fossil, Skagen, Casio, or similar brand watch has stopped — the Renata 377 is almost certainly the right cell if the manual specifies SR626SW or 377
• Households with multiple small electronic devices — bathroom scales, calculators, small LED torches, and some fitness trackers all run on 377 or equivalent cells
• DIY gift-repairers who like fixing a beloved watch rather than paying a jeweller's labour charge for a five-dollar battery

Skip this if you are after a high-capacity cell for a high-drain wearable or a device that runs constantly with backlighting. There are lithium alternatives better suited to those use cases, and the Renata 377 is not designed for them.

Alternatives Worth Considering

• Sony SR626SW — Sony makes a solid silver oxide cell that competes directly with Renata. If Sony is what is in stock when you need a replacement, it is a perfectly valid choice. Renata edges it out slightly in OEM adoption and shelf life.
• Energizer 377/ SR66 — Energizer is a household name and their silver oxide 377 performs reliably. The trade-off is that Renata typically offers the 3-pack at a marginally better per-cell price, and Renata's OEM reputation carries a bit more weight in watch-circles.
• Maxell SR626SW — Another credible Japanese manufacturer. Maxell cells are generally fine, but they are harder to find in the Renata price range and occasionally show up with shorter stated shelf life on retail listings.

FAQ

Final Verdict

The Renata 377 SR626SW watch battery is exactly what you want from a button cell: clean voltage, solid build quality, and a chemistry that plays nicely with precision quartz movements. It is not the cheapest option on Amazon, but the price premium over generics is justified by Renata's OEM pedigree and consistent quality control. For watch owners, collectors, and anyone maintaining small household electronics, this 3-pack belongs in a drawer — right next to the case-back tool and the watch you keep meaning to fix.