Wall mounted, rechargeable lithium ion battery
with liquid thermal control."
That is a from the Tesla Powerwall Site.
AFAIK up to this point all of Tesla's batteries use multiple strings of 18650 Lithium ion cells (same as your laptop
computer). These things have a long track record
of making fire if mishandled.
UR right about life away from the power and water
utilities requires us boaters to do a lot of things inconceivable to dirt dwellers.
Try Navy SEALS
and ASDS for info on the total destruction of a special ops submarine by lithium batteries. Almost a billion dollars in US money
(not sure if it was tax money
or just some printed by the Fed) up in smoke. I worked on that one.
Going to sea has enough hazardous with out dragging any lithium along. Same would probably be said by Boeing and the Dreamliner folks.