The fuse will literally warm up, all the time. This is a power loss. Using the properly sized fuse, and wire will be the safest and most efficient solution.

A 12 volt, 200 amp hour battery can produce 100 amps of electricity for 2 hours

Volts: Energy Potential,

Fuses are rated in amps, and if you know how many amps a wire can carry, you will know what type of fuse it needs. If you follow a few simple rules, you will be good to go.

Have the voltage monitor mounted in an easy to see location.

Water Hose Analogy: Current is similar to the rate of flow.

Also, if you do not use your battery or only discharge a little bit, such as 98% of the total capacity, other problems can occur. You need to discharge to at least 90%, once a week, to keep the batteries happy.

Water Hose Analogy: Volts are similar to the pressure of water in a garden hose.

Big Appliance = Big Wire = Big Fuse