https://youtu.be/wpyVrm5WXgU?si=zwsVHiC1oMgMYn21
per comment
Sweden cools runaway battery packs by driving a hollow spike through
the housing with a sledge hammer while pumping water through it. You
can quench a thermal runaway in ~10min using less than 100L of water
that way, then you only need a trickle to manage self-discharge heat
and flush corrosion byproducts.
also per comment - elsewhere in europe they dunk the whole car in a
skiff full of water