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South Korea begins work on second sub with lithium-ion batteries

Illustration: ROK Navy file photo

South Korea’s defense procurement agency (DAPA) announced on December 31 that work is underway on the second KSS III Batch II submarine for the Republic of Korea Navy.

The steel-cutting ceremony took place at the Daewoo Shipbuilding & Marine Engineering (DSME) shipyard in Geoje, on December 30. The same company is also building the first unit in the class, which is scheduled to be handed over in 2026.

The second boat that started construction last week is scheduled for delivery in 2028, after it completes trials.

Batch II subs are an upgraded variant of the Dosan Ahn Changho-class, which has already started entering service. Three of the 3,000-ton boats have already been launched.

Batch II units are slightly larger than the boats of the first batch, with a displacement of 3,600 tons. They are also expected to have ten vertical launch tubes for submarine-launched ballistic missiles (SLBM), compared to the six found on Batch-I submarines.

The most distinctive feature of the next-generation submarines is arguably their propulsion system, which will rely on lithium-ion batteries instead of conventional lead-acid ones. Coupled with an air-independent propulsion system, the new batteries will allow the Batch II subs to stay submerged for longer periods of time.

South Korea is the second country to introduce lithium-ion technology on its submarines, with the first being Japan. It is worth noting that the US Special Operations Command operates dry combat submersibles (DCS) equipped with lithium-ion fault tolerant (LiFT) battery systems.

Another advantage of the Batch II boats is their high degree of localization, as they feature 80 percent of indigenous work and technologies. While benefitting local industry, this will also streamline the maintenance of the assets.