There's a specification sheet for a Winston Battery WB-LYP10000AHA battery pack, which markets itself as used in the Yuan.
It's listed as 31MWh with a weight of 335tonnes. That works out as 92Wh/kg, which is slightly more than the GS-Yuasa industrial batteries.
If the Soryu is somewhat heavier than the Yuan, then 350-400kg of battery in the Soryu sounds like a reasonable working assumption.
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I'm also looking at the differences between the Mk1 and the Mk2 Soryu.
The Liquid Oxygen tanks and the Stirlings have been replaced by an "unknown" space plus a third battery compartment which looks larger than the other 2 compartments.
If the original Soryu has 400kg of battery and I assume a normal deck height of 2.4m, I get a figure of 229kg for this third compartment.
But if they start using those "unknown" spaces as a 4th battery compartment, I get another 257kg of battery
So theoretically, the Soryu could have up to 900kg of battery at a stretch. If we use your estimate of 110Wh/kg, that's almost 100MWh of battery.
But there's so many assumptions built into this model.
And there are some comments on the Taigei having additional diesel generators using up some of the free space.
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