July 17, 2026

Japanese LIB, Diesel & Post Taigei Program - TABLE

On July 18, 2028 wispywood2344 kindly provided the following:

Hi Pete
To maximize the performance of [Lithium-ion Batteries] LIBs in a  conventionally powered submarine, simply replacing conventional [Lead-acid Batteries] LABs with LIBs is not sufficient.
The JMSDF [Japanese Navy] is refining its design in stages, as described below.

The [Japanese Navy] adopted the 1st-generation submarine LIB [submarine Lithium H? = ] “SLH
[Pete comment - this may be a cover name for LCO = 
Lithium Cobalt Oxide (LiCoO2). The "Battery University" comments on LCOs for small consumer devices, are probably unrepresentative of much larger (100s of tonnes) scale, more advanced Japanese submarine battery developments]
on the 11th Soryu-class (Soryu Mk.2 [named by Pete] ), and eliminated both AIP and LABs.

However, since the [submarine Lithium H?] “SLH” had the same dimensions as conventional LAB, it created significant dead space within the battery compartment.[1]

Furthermore, because the diesel generators were not modified, the improvement in the indiscretion ratio was limited.

The same situation applied to the first 3 Taigei-class submarines in the Table below (they are the Taigei Mk.1s). Into each of those Taigeis 2 x Kawasaki 12V25/25SB diesel generators were fitted (see redded diesels in the Table below).

But in the 4th Taigei (the first Taigei Mk.2) two newly developed diesel generators were fitted. These were 2 x Kawasaki 12V25/31S. Each generator had increased output (up to +50%) leading to a substantial improvement in the indiscretion ratio.[2]

Going forward, the 11th Taigei (Taigei Mk.3) is expected to adopt the 2nd-generation submarine LIB known as “SLI” formula unknown? [3]

This will improve not only the energy density of individual battery modules but also the packing density of battery modules within the battery compartment, leading to a significant improvement in total energy storage capacity.[1]

In the post-Taigei-class submarines [Pete comment. Might the new class name be "Raijin" God of lightning/storms or "
Wani" sea monster/shark?] expected to enter service around 2034, the total ship design will be optimized, including the dimensions and shapes of the internal compartments and the propulsion motor.[4][5]

[Pete comment - Wiki reports - KHI received a research and development contract from the Japanese Ministry of Defense on December 29, 2023 to design a post-Taigei class diesel electric submarine possibly with VLS to deploy stand-off missiles? Was KHI also asked to do an initial nuclear reactor study?]

I find it fascinating to see what requirements countries that do not need large conventionally powered submarines to the same extent as Japan place on their own submarines, and in what direction they are evolving them."

[1]  https://warp.ndl.go.jp/20250801/20250801001909/https://www.mod.go.jp/atla/research/ats2024/pdf_exhi_pos/p-13.pdf
[2]  TRDI specification "New Snorkel Generator System (Part.2)" p.4
[3]  https://www.mod.go.jp/atla/souhon/choutatsuyotei/r08_choutatsuyotei.xlsx#
See row2459   
[4]  https://www.mod.go.jp/atla/research/ats2025/pdf_oral_matl/1112_1100_s13.pdf
[5]  https://warp.ndl.go.jp/20250901/20250901000226/https://www.mod.go.jp/atla/research/ats2024/pdf_exhi_pos/p-18.pdf  

Regards wispywood2344

-------------------

This Table is unique to Submarine Matters mainly created by "S"/Anonymous wispywood2344 and Pete.

Japan's Diesel-Electric Classes of Submarine (SSKs)

The 2nd Oyashio class, Soryus & Taigeis as at March 13, 2026. 

SS
No.
Diesel Type
Motor
Build No
Name
Pennant
No.
Ministry of Finance (MoF) approved
Ministry of
Defense Budget
in Billions of
Yen (¥B)
LABs +
AIP:
or LIBs
Laid Down
Laun
-ched
Comm
i
ssion
ed
Built
By
5SS + 6SS
now training

Oyashios
8105 +
8106 Oya
shio
¥52.2B FY1993
2 x 12V25/25S 
diesels for all
Oyashio class
(each diesel
2,000kW)
LABs only
1994 & 1995
1996 &
1997
Built
at
KHI
7SS-15SS
8 active Oyashios 
10 subs
SMC-7?
8107
-8115
various
SS-591-600
¥52.2B per sub
FY1994-FY2003
LABs only
 15SS Feb
2004
15SS
Nov
2006
15SS
Mar 2008
MHI
&
KHI
16SS
12
Active

Soryus/
Dragon
class  Mk I
8116
Sōryū
means
dragon
2,900 tonnes
surf-
aced
SS-501
¥60B FY2004 
Mk.1 LAB+AIP Soryus have 2 x Kawasaki 
+ a SMC-8 motor
LABs + AIP
Mar 2005
Dec 2007
Mar
2009
Built
at
MHI

Home
Port
Kure
17SS
8117
Unryū
SS-502
¥58.7B FY2005
LABs + AIP
Mar 2006
Oct 2008
Mar
2010
KHI
Kure
18SS
8118
Hakuryū
SS-503
¥56.2 FY2006
LABs + AIP
Feb 2007
Oct 2009
Mar
2011
MHI
Kure
19SS
8119
Kenryū
SS-504
¥53B FY2007
LABs + AIP
Mar 2008
Nov 2010
Mar
2012
KHI
Kure
20SS
8120
Zuiryū
SS-505
¥51B FY2008
LABs + AIP
Mar 2009
Oct 2011
Mar
2013
MHI
Yokosuka
21SS LIBs Concept
Research
Project
No 21SS built. It was an 8 year research project on LIBs. 1st LIBs sub launched was 27SS in 2018.
   


22SS
8121
Kokuryū
SS-506
¥52.8B FY2010
LABs + AIP
Jan 2011
Oct 2013
Mar
2015
KHI
Yokosuka
23SS
8122
Jinryu
SS-507
¥54.6B FY2011
LABs + AIP
Feb 2012
Oct 2014
7 Mar 2016
MHI
Kure
24SS
8123
Sekiryū
SS-508
¥54.7B FY2012
LABs + AIP
KHI
Kure
25SS
8124
SS-509
¥53.1B FY2013
LABs + AIP
22 Oct 2013
12 Oct   2016
MHI
Yokosuka
26SS
8125
SS-510
¥51.7B FY2014
last SMC-8 motor
LABs + AIP
2014
6 Nov 2017
KHI
Kure
27SS a Soryu
"Mk II" as it
has LIBs. 1st
Soryu
Mk II 
8126
Oryū
11th
Soryu
SS-511
¥64.4B FY2015 
with 2 12V25/25SB diesels (totaling 4,240kW) 
SMC-8B motor [Wispy+Anon
agree it has 640 LIB/SLH modules], other improvements
LIBs only
(SLH type)
Nov
2015
4 Oct
2018
2020
MHI
Kure
28SS Soryu
Mk II, 12th &
final Soryu
8127
SS-512
¥63.6B FY2016
"2,950t" surfaced
2 12V25/25SB 
diesels.
LIBs
Jan 2017
KHI
Yokosuka
29SS
1st
Taigei
Class

means
Whale
3,000 tonne
(surfaced)
8128
Taigei
"Big 
whale
"
Used as
test
sub. Not
opera-
tional
SS-513
¥76B FY2017 (Heisei 29)
Higher ¥76B budget 
may be due to 1st of class many changes.
Kawasaki
12V25/25SB
2 x 12V25/25SB
says 640 LIB/SLH modules, Anon says 720.]
SLH
LIBs
maybe
960

14 Oct
2020
 
9 Mar 2022
MHI

Home
Port
Yokosuka
30SS 
2nd Taigei Class 
8129
Hakugei
"White
whale
"
First
opera-
tional
Taigei

SS-514
¥71.5B FY2018 
(Heisei 30)
12V25/25SB
says 640 LIB/SLH modules, Anon says 720.]
SLH
LIBs
KHI

Home
Port
Kure
Reiwa Era 01SS 
3rd
Taigei Class
8130
Jingei
"Swift
whale
"
SLH
LIBs
maybe
960+
8 Mar
2024
MHI
02SS 
4th
Taigei Class 
8131
Raigei
Thunder
whale
SS-516
¥B70.2B FY2020 (Reiwa 02)
Improved SLH LIBS.
12V25/31S 
New
2 x 12V25/31S
diesels (totaling
Improved
 SLH
LIBs
26 Mar
2021
KHI
03SS
5th Taigei Class
SS-517
LIBs 
19 Apr
2022
10 Mar
2026
MHI
04SS
6th Taigei Class
SS-518
LIBs
28 Mar
2023
March? 
2027
KHI
05SS 
7th Taigei Class
8134
SS-519
LIBs
17 Apr 2024
2026
March? 2028
MHI
06SS
8th Taigei Class
8135
SS-520
LIBs 
19 Dec
2024
2027
March?2029
KHI
07SS 
9th Taigei Class
8136
SS-521
¥B116.1 FY2024  for 9th Taigei page 23 [1]
LIBs
2026
2028
2030
MHI
08SS 
10th Taigei Class
8137
SS-522
¥B120.8 "for 10th Taigei... for enhanced detection capabilities & manpower saving systems for effective intelligence & surveillance activities" page 27 [2]
LIBs
2027
2029March?
2031
KHI
Key to Table: Table information provided by S & wispywood2344 to Submarine Matters. LABs = lead-acid batteries, AIP = air independent propulsion, LIBs = Lithium-ion Batteries. 
¥***B
= Billion Yen. MHI = Mitsubishi Heavy Industries, KHI = Kawasaki Shipbuilding Corporation of Kawasaki Heavy Industries. 
---

[1] Japanese “Ministry of Defense: Progress and Budget in Fundamental Reinforcement of Defense Capabilities: Overview of the FY2025 Budget” page 23 
[2] Japanese “Ministry of Defense: Progress and Budget in Fundamental Reinforcement of Defense Capabilities: Overview of the FY2026 Budget” page 27

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