Rapala Lithium Ion Cordless Fillet Knife Ready to match up with any filleting task, the new Lithium Ion Cordless Fillet Knife produces 80 continuous minutes of runtime without any loss of power. Lithium Ion batteries provide a consistent speed and torque from fillet to fillet, without reduced power or slow down as battery power wains. Fast change time, a full 80 minute runtime charge takes less than 2 hours. Low "memory" effect increases the number of charge/discharge cycles for longer battery life.