Electrolysis of water and brine
For the launch of the book, we created a series of five short films to showcase different techniques that would be vital for surviving the immediate aftermath and rebuilding the capability of your post-apoclyptic society. This one shows how to use a scavenged deep-cycle battery (perhaps from a golf buggy, mobility scooter or caravan) and the alternator from a car to keep your community electrified, and to perform electrolysis for creating crucial substances for yourself. Also see the linked series: (1/3) How to open a can without a can opener, (2/3) How to start a fire with everyday items and (3/3) How to make a gasifier stove.