Re: Extinguishers...
Build separate (empty) pools, one per pack. Remotely closeable drainage to stop them filling with rain water (yeah even in Aus). Once a fire starts, flood the pool.
Does increase construction and deployment costs though, and all the concrete needed to make the pools somewhat dents the eco credentials of these battery schemes.
Question though. If the lithium and electrolyte therefore aren't consumed, will they later spontaneously combust if the pool is drained?