Japanese Submarine LIB distributions & other calculations.

Inspired by Anonymous's hard work are very simplified diagrams of Japanese subs -

with the estimated number of Lithium-ion Battery (LIB) modules in yellow. 

All this highlights the advantages of Japanese all LIB Taigei subs over the 50 tonne lighter

all LIB Soryu Mk IIs (namely JS Oryu and JS Toryu). The LIB distribution

diagrams are: 

			Fin/Sail--------
			Command Rm
Propuls-n	Diesel	Databases-----	Command Rm	Torpedo Rm	Bow Sonar
Motor	Engines	Crew sleeping	& eating areas	Torpedo Rm	Bow Sonar
Fuel/watr	Fuel/Water	80 LIBs a…..	Stores-----	Stores-----	Fuel/Water
Fuel/watr	Fuel/Water	80 LIBs b…..	240 LIBs c…..	240 LIBs d..	Fuel/Water

 Figure 1. - Schematic structure of Oryu/Toryu (Soryu Mark IIs) - noting:

-  5 Bulkheads: Propulsion Motor/Diesel/LIBs(ab)/LIBs(c)/LIBs(d)/Torpedo Room (Rm)

-  Number LIBs = 640 = 80 (a) + 80 (b) + 240 (c) + 240 (d)

-  Higher center of gravity due to 80 LIBs in higher LIBs "a" section

-  LIBs in "a" section increases vertical stray magnetic field problems. Stray fields can be more easily electro-magnetically detected by ASW enemies. Strays fields can also upset delicate electronic equipment in the submarine.

-  Regarding "Fuel/Water" once the Diesel Fuel is consumed the fuel tank is filled with seawater to maintain constant weight distribution (important for buoyancy and trim).

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			Fin/Sail-----------
			Command Rm
Propuls-n	Diesel	Databases-----	Command Rm	Torpedo Rm	Bow Sonar
Motor	Engines	Crew sleeping	& eating areas	Torpedo Rm	Bow Sonar
Fuel/watr	Fuel/Water	FreshWater	Stores-----	Stores-----	Fuel/Water
Fuel/watr	Fuel/Water	LIBs A, LIBs B	LIBs C, LIBs D	LIBsE, LIBsF	Fuel/Water

Figure 2. - Schematic structure of Taigeis - much improved from Toryu/Oryu (Soryu Mark IIs) noting:

-  Greater number of LIBs for longer full submergence / more discrete = 720 LIB modules = 120 x 6 in each of (A, B, C, D, E & F) sections
-  Less vertical stray magnetic fields
-  Lower center of gravity, better for calculating and maintaining buoyancy and trim.
-  Less potential leakage of dangerous gases caused by fire from battery sections to upper sections. 

-  Easier to deploy downward traveling fire suppressant gases as all batteries are contained in bottom deck of a Taigei.

-  Fewer Bulkheads: maybe as low as 4 ie. Propulsion Motor/Diesel / LIBs (ABC) /LIBs (DEF) / Torpedo rooms.

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Anonymous on November 8, 2022 provided extra calculations, which are reproduced below:

Energy of total Japanese submarine LIBs (codenamed “SLHs”) is estimated to be 62-74MWh and 70-83MWh for Oryu/Toryu (ie. The Soryu Mk IIs) and the Taigeis, respectively. This suggests maximum fully submerged endurance of 9-11 days and 10-12 days respectively [3].

Calculations:

[1] https://www.gs-yuasa.com/gyt/jp/products/space/ [Japanese doc . Just right-click mouse to Translate to English.]

High performance lithium-ion battery for spacecraft (eg. satellites and “space probes”): energy density 168Wh/kg, 130(Width) x 50(Depth) x 271(Height) all in mm
Energy density of this battery is ca.20% higher than [2] suggesting energy density of [2] is 140Wh/kg.

[2] https://www.gs-yuasa.com/gyt/jp/products/lithium_l.php [Japanese doc . Just right-click mouse to Translate to English.]
Large lithium-ion battery for space: energy density 140Wh/kg

[3] Estimated energy of submarine (Oryu/Toryu, Taigeis) with SLH (weight 770kg) based on [1] and [2]

If 10% of SLH is used for "frame" [does this mean for internal battery function, eg. keeping battery warm enough to be efficient?] and so on, then energy of SLH is 0.097-0.116MWh
(770kg x 140Wh/kg x 0.000001 MW/W or 770kg x 168Wh/kg x 0.000001 MW/W)

Energy: 62-74MWh [Oryu/Toryu, 640SLHs], 70-83MWh [Taigeis, 720SLHs]
(0.097MWh x 640 or 0.116MWh x 720 for Oryu/Toryu)

If daily energy consumption at surveillance speed [<4knots] is 6MWh [4] and depth of discharge is 90% for SLH, then maximum endurance is 9-11days [for Oryu/Toryu] and 10-12days [ for the Taigeis].
(62MWh / 6MWh x 0.9 or 74MMWh//6MWh x 0.9)

[4] Considering the significant electrical needs of submarine sonar systems and other non-propulsion electrical “hotel load”, then requirement may be 200kW. Energy requirements for propulsion at surveillance speed may be 50kW. Then daily energy consumption is 6MWh (=(200kW+50kW) x 24hours).

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For more launch date and other details of all these Japanese submarines see Submarine Matters Oyashio-Soryu-Taigei Table here.