Choosing the wrong coin cell battery can ruin your favourite timepiece. If you are shopping for a replacement SR621SW (364) battery, you have likely encountered three dominant brands online: LiCB, Renata, and Maxell.
While they all look identical on the outside, they are built very differently on the inside. This comprehensive review breaks down the pros, cons, and performance metrics of all three options to help you choose the right one for your device.
1. LiCB SR621 SW: The Budget Bulk Champ
LiCB is a high-volume manufacturer based out of Guangzhou, China. They specialise in budget-friendly multi-packs sold directly to consumers online.
- Chemistry Type: Primarily Alkaline or low-cost Lithium variations.
- Manufacturing Origin: China.
- Best For: Toys, low-cost key fobs, backup LED decorations, and low-drain household goods.
The Pros
- Unbeatable Value: You can often buy a 10-pack or 20-pack of LiCB batteries for the price of a single premium cell.
- Decent Initial Power: Fresh out of the pack, they provide stable energy for basic electronic circuits.
The Cons
- Sloping Discharge Curve: Unlike premium options, the voltage drops steadily as the battery drains, which can cause watches to lose accurate time keeping.
- Higher Leak Risk: Under high humidity or prolonged stagnation, the basic seals are more prone to failure than their premium counterparts.
2. Renata SR621 SW: The Luxury Swiss Standard
Owned by the Swatch Group, Renata is the undisputed leader in European horology. If you buy a luxury Swiss watch (like an Omega, Tissot, or Longines), it likely came from the factory with a Renata battery inside.
- Chemistry Type: Premium Silver Oxide (Zn/Ag₂O) — 0% Mercury (Hg).
- Manufacturing Origin: Switzerland.
- Best For: High-end Swiss quartz movements, luxury chronographs, and precision medical devices.
The Pros
- Flat Voltage Discharge: Silver oxide chemistry guarantees a perfectly flat 1.55V current until the cell is entirely depleted. Your watch will not lose seconds as the battery ages.
- Eco-Friendly Certification: The modern SR621SW range features a guaranteed 0% Mercury and 0% Lead construction.
- Prestige Quality Control: Manufactured under tight aerospace-grade Swiss specifications.
The Cons
- The “Dead Battery” Risk: If left dead inside a watch for many months, the seal can degrade, meaning you must replace a dead Renata cell promptly.
3. Maxell SR621 SW: The Flawless Japanese Icon
Maxell pioneered Japan’s first silver oxide cells in the 1970s. Today, they are the go-to power source for Japanese movements like Seiko, Citizen, Casio, and Miyota.
- Chemistry Type: Premium Silver Oxide (Zn/Ag₂O) — 0% Mercury (Hg).
- Manufacturing Origin: Japan.
- Best For: Everyday commuter watches, high-humidity environments, and long-term shelf storage.
The Pros
- Advanced Leak Protection: Maxell utilizes a proprietary liquid-alkali electrolyte gel paired with a robust negative-seal structure. It rarely leaks, even if left dead for months.
- Superior Shelf Life: Rated for a reliable 5+ year shelf life, making them ideal for buying in small multi-packs.
- Extreme Climate Stability: Known to handle hot, humid, and tropical weather changes without swelling.
The Cons
- Counterfeit Risk: Because they are so popular globally, buyers must ensure they are purchasing from authorized, reputable dealers to avoid fakes.
Head-to-Head Comparison
| Feature | LiCB SR621SW | Renata 364 / SR621SW | Maxell 364 / SR621SW |
|---|---|---|---|
| Country of Origin | China | Switzerland | Japan |
| Chemistry | Alkaline Matrix | Silver Oxide | Silver Oxide |
| Capacity (mAh) | Variable / Lower | ~16–18 mAh | ~16–18 mAh |
| Leak Resistance | Basic | Advanced Dual-Seal | Elite Anti-Blowout |
| Best Device Match | Children’s toys / Fobs | High-end Swiss Luxury | Japanese Quartz / Daily Wear |
The Verdict: Which One Should You Buy?
Buy LiCB if…
You have a fleet of inexpensive children’s toys, cheap digital clocks, or simple garage door clickers where losing time doesn’t matter and you just want the maximum number of batteries for your money.
Buy Renata if…
You are servicing a high-value Swiss timepiece or precision device. The factory-grade companion fit ensures your luxury gear operates exactly as the engineers intended.
Buy Maxell if…
You want the safest, most reliable daily-wear battery. With its superior leak resistance and stable 5-year shelf life, Maxell represents the best overall performance and safety balance for the average watch owner.
