The Hard Switch By Owen D. Pomery

Ada, Haika, and Mallic are on a mission... one last mission, before everything, everywhere shuts down. They're raiding old, abandoned spaceships and wrecks for the (sometimes-expensive) parts - and they make just enough money to get by. But living their nomadic, exploring life isn't sustainable when they can t afford fuel anymore. The time is coming when the mineral that makes inter-system jumps possible runs out.

When it does, the scattered inhabitants of the vast galaxy will be stuck where they are. Everything will be different... unless the discovery in the latest wreck Ada, Haika, and Mallic are scavenging can unlock a whole new kind of interstellar transit.