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I would like to see that picture. Upon further review it seems like it might just make sense to leave the 48 volt modules intact and use an inverter that accepts 48 volts. Considering all the 48 volt modules have posts and would have intact BMS leads it might just be the way to go. As I learn more about these batteries and the lithium world I feel more comfortable breaking away from what is normal for the lead acid 12 volt world.
I would also recommend staying at 48V. There are for example hot water heaters at this voltage and this standard is gathering momentum. Propulsion for both EVs and EBs (electric boats) are now invariably 48V and are going up by a multiple of that to 96V, 144V, etc. I believe home DC standard fed by solar panels includes 48V. Most likely you will be able to find appliances at this voltage.

Note that 12s is a bit anemic for 48V and ideally you want to be 13s or 14s. For my projects, I am going 14s. http://www.diyelectriccar.com/forums/showthread.php/18650-13s10p-project-48v-x-34ah-188618.html
 

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Buy you def want good BMS protection on a boat using a chemistry at risk of thermal runaway.

LFP would lots safer
In addition to the mandatory BMS, how about flooding the pack enclosure with seawater if a thermistor is triggered? Let's say two thermistors for every 1 kWh. If the pack is below waterline, no pump is needed. Of course pack must be in its own compartment, and an independent power source needed for the pump/valve.
 

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Actually I'm pretty sure shorting out all the cells with highly conductive seawater would have unintended consequences even if they weren't in the middle of a thermal runaway catastrophe.

Not to mention most boat owners are doing their best to keep that salty wet stuff on the **out** side of the hull.

:cool:
Seawater's resistance is in the hundreds of ohms. You need milliohm shorts to generate any kind of power with any consequence. One would lose the electronics and cells maybe, but the fire will be contained. In fact the shorting at hundreds of ohms is exactly what you need to deplete the cells adjacent to the runaway cell. Note that the battery pack should be distributed in two or more locations throughout the boat anyways, and should not be all localized to one tight spot. I would be happy to have a compartment wet with seawater than to have a fire raging out of control.
 
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