2S, 3S, 4S, 6S: what the S-number means
The S-number counts cells in series, and it sets the pack voltage. This guide explains the common counts and why the charger must match the count.
Dimension-callout pouch outline — the site's recurring diagram motif. It is a schematic, not a photograph of a product, factory or customer project.
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S stands for series. 2S means two cells in series, nominally 7.4 V; 3S means three cells, 11.1 V; 4S means four cells, 14.8 V; 6S means six cells, 22.2 V. The number is a property of the pack, not of the cell: the same cell can appear in a 2S pack and a 3S pack, and the two packs are different products with different voltages, chargers and protection.
The most common buyer error with series counts is mismatching the charger. A charger built for 2S will not correctly charge a 3S pack, and a charger built for a higher count must never be used on a lower-count pack without a design that explicitly supports it. This site does not sell a charger range, and the charging guide here covers cell-charging basics only; for a pack purchase, confirm the matched charger and the balance-charging arrangement with the supplier as part of the same inquiry.
Higher series counts suit devices that need higher voltage — larger drones, bigger RC cars, equipment with motors — while lower counts suit small electronics and handheld devices. When you inquire, state the series count your device expects rather than asking for a generic recommendation: the count, the capacity and the peak current together describe the pack, and any one of them alone does not.