Anonymouses "Japanese Submarine LIB distributions & other calculations" of Nov 11, 2022 generated many comments.
Those are the comments not incorporated into "REVISED Japanese Sub LIB distributions, Othercalculations" of Nov 17, 2022.
Those comments are below and were made between November 12 & 16, 2022:
"I'm a different Anonymous commented Nov 12, 2022:
A power load for propulsion of 50 kW is far too low for a 3,000 tonne submarine [like a Japanese Taigei or Soryu MK. II]. 50 kW being more like the power of an Outboard engine for a small amateur fishing boat or probably the power needed for a submarine to barely stay idle in a current.
This is noting the Kuroshio current in the Tsushima Strait is above 5 knots. 300 kW is probably the minimum for a sub, necessary to reach 5 knots.
A simple back of the envelope calculation considering the public data (eg. French Jeumont engines):
- on the 2,000 tonne S-Br (Brazilian Navy Scorpene) where 2,900 kW is needed to sprint at 20 knots submerged
- on the Barracuda/Suffren class SSN (5,000 tonnes) where 15,000 kW is needed to reach 28 knots
On the lower length/diameter L/DTaigei at 3,000 tonne, (the power need evolves as the square of the speed) this rule of thumb will lead to 300+ kW at 5 knots. This would mean a week in a real tactical situation which is remarkable
More important is the power density, the shape of the discharge /charge curve and the charging speed (under snorkel) to decrese the indiscretion ratio.
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wispywood2344 commentedNov 13, 2022:
There is a serious clue about the energy capacity of Japanese submarine LIB "SLH" hidden in a document published on the Web by the Japanese MoD.
This is it. [1]
It should look familiar to you.
Display the graph on the page 2 of this document and enter "Ctrl+A," you can reveal the HIDDEN (or FAILED TO BE DELETED) LETTERS on the vertical axis. [2]
Therefore, we can assert that the capacity of a lithium-ion cell used in "SLH" is 1000-2500 Ah.
Since "SLH" uses LCO as the positive electrode material and carbon as the negative electrode [3],the nominal voltage of a "SLH" module is around 37V.
Taken together, the energy capacity of "SLH" can be estimated to be around 36-93 kWh per module.
[1] FY2006 Post project evaluation "Development of new submarine main battery"
[2] http://blog.livedoor.jp/wispywood2344/others/SLH_Capacity_Leakage.gif
[3]"Realization of the world's first submarine equipped with a lithium-ion battery system", at Defense structure improvement foundation at https://ssl.bsk-z.or.jp/kenkyucenter/pdf/gyt20201210.pdf#page=2
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An Anonymous commentedNov 14, 2022:
Once, an influential politician on Japanese MoD revealed there was an improved version (SLH2?) of the current lithium-ion battery (=SLH) for submarine, but due to budget constraints, the improved version could not be obtained.
So, SLH2 might be based on is based on high performance lithium-ion battery for space (energy density 168Wh/kg), while SLH might be based on is based on large lithium-ion battery for space (energy density 140Wh/kg).
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SONARS are High Hotel Load Users
C commented Nov 14, 2022:
I think rather a lot hinges on the hotel load. I read all sorts of numbers from 50 to 200Kwh, but its all very iffy and vague.
My point is that is in all my reading the composition of hotel-load is glossed over, but maybe its worth some drilling down into this? eg: The Thales VELOX-M8 Broadband Sonar Interceptor [Control-F for "sonar" within this Barracuda SSN link] uses up to 400W when running (which I suspect is a max number). One could put some fair estimates on air circulation systems based on industrial HVAC. Ditto for refrigeration. Etc.
I confess I cant really contribute very much to this, I have snippets only, but I think its critical in understanding practical endurance for modern boats - if designers were able to halve the hotel load, they'd double endurance!
eg. There is also the issue that any computational system that generates waste heat, will also need that heat removed, essentially doubling the energy cost (this is the classic cost issue with massive datacenters), ergo a BIG incentive to use highly efficient [digital signal processors] DSPs, [central processing units] CPUs, etc. I suspect most of the big sonar rigs designed by nuclear sub club countries are not overly concerned with power consumption (obviously), but other vendors may (or may not) be far more judicious.
Something to chew on.
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Another Anonymous commented Nov 16, 2022:
The French SSN, Barracuda-class submarine is equipped with the Thales VELOX-M8 intercept sonar[1]. But, a conventional submarine with limited power supply cannot be equipped with this kind of high power consumption sonar [2] and is equipped with low power consumption and less sensitive sonar instead.
[1] Barracuda SSN Specs: at Very long link:
[2] SHIPS OF THE WORLD, Special issue 159, page 21, by Ex-Fleet Commander of JMSDF [Japanese Navy] Masao Kobayashi. [scroll down herefor his photo and biodata.]
“In order to maintain long-term diving, it is essential to reduce the hotel load, and it is necessary to reduce the power consumption of the onboard equipment. This makes a great impact on the onboard equipment. For example, the [Virginia sub's BQQ-10 spherical bow sonar array] generates a uniform sonar beam toward not only in a right and left direction but also in an up and down direction and is very effective. But there is no conventional submarine equipped with the spherical array because the beam generation of this array needs a huge amount of calculations, i.e., huge power consumption.”