Just load it with 8 “D”cell batteries and store it until it’s needed. The EZ PowerPak can be used to power a multitude of accessories under 3 amps without depending on the boats main power system - fans, portable lights, kid’s video games or a fishfinder. In an emergency you can use it to power up a GPS, VHF or charge a cell phone. The comfortable shoulder strap makes it truly portable. Product Features: 1 Waterproof Built in battery tester shows when voltage is above 10 Volt, between 8 and