Taiwan's "Indigenous" Subs a Japanese-US Hybrid: Lithium Batteries

 Page 6 of Warships International Fleet Review (Paysite) January 2022 describes:

Taiwan's Indigenous Defence Submarines (IDS) design, first one laid down November 2021 "is reported to be equipped with locally developed Lithium-ion batteries [LIBs] instead of an ...AIP system." NavalNews indicates the same.

In the context of externsive Japanese design and worker assistance, this suggests Taiwan is going the most modern Japanese Taigei-class route of using LIBs rather than the older Soryu's mix of lead-acid batteries and AIP.

Wiki (which has compiled many IDS details) reports:

"In May 2019, Taiwan revealed a scale model of its chosen design for an indigenous built diesel-electric attack submarine. The external design appears to resemble Japan's Sōryū-class SSKs by having an X-form rudder.^[9] 

The boats will be assembled using Japanese construction techniques in Taiwan. A Japanese team consisting of retired engineers from Mitsubishi and Kawasaki Heavy Industries is believed to have provided technical support." 

Taiwan supplied model. Some interpret it as looking like a a Japanese Soryu sub. But it could also look like a Japanese Taigei - with its longer sail/fin.
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Warships further reports the US including Lockheed Martin and Raytheon is supplying the Combat System (which includes sensors, databases and weapons (including the Mark 48 torpedo and Harpoon ASMs)). Wiki describes this as a "version of the AN/BYG-1 submarine combat management system" used in US Navy nuclear submarines." 

A major difference will be:

-  Taiwan's sub displacing "2,500 tonnes" (presumably surfaced) and around 70m long (see right sidebar)

- while, with more certainty, Japan's Taigeis are 3,000 tonnes (surfaced) and 84m long (see right sidebar).

Taiwan's subs might be smaller in size as a budgetary measure and also a more defensive mission (to help deter a Chinese attack on Taiwan).

Extensive Japanese and US parts and assistance will likely help Taiwan achieve very short timelines: ie. launching the first sub in 2023 and (Warships expects) commissioning in 2025.  

Pressing needs to achieve these goals, of course, includes the obsolete reality of Taiwan's existing subs and dire threat of China attacking Taiwan (possible any time after the February 2022 Beijing Winter Olympics).    

The IDS's Diesels?

Ordinarily the IDS would use the world's most common submarine diesel, the MTU 396 (which may steadily be replaced by the MTU 4000). However, Japan may possibly be supplying a Kawasaki diesels of the Types used on Japan's Oyashios (12V25/25S), Soryus (12V25/25SB) and, less likely the Taigei's more powerful 12V25/31S diesels ) - see Japanese Submarine TABLE here. 

If Taiwan does not mention its the IDS's diesel propulsion at all this may indicate its using 2 Kawasaki diesels, which may, in turn, be operating with Japanese designed LIBs.

Just Export Specification US and Japanese Equipment to Taiwan?

Many Chinese/PRC firms have invested in sensitive Taiwanese economic sectors, like ports. Also many Taiwanese have lived for many years in China and transit between Taiwan and China often.

So the US and Japan are probably mindful that Taiwan may be heavily penetrated by Chinese intelligence. Accordingly the submarine components that the US and Japan may have sent to Taiwan might be less sensitive export specification/grade equipment. 

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