because those fuses that you see there is the LOAD that each element of the car has, for example the sound equipment consumes 10 amps and in the car in the rifle there is one of 15 amps, the maximum capacity of the accumulator has NOTHING to do with the individual consumption of each device, that is the problem that you want to see that the battery is 80 amps / HOUR and should burn all devices and thus does not work, it is the other way around the battery provides the amperage that EVERY ELEMENT REQUESTS and if it burns A fuse is because the element that has a fault is going to SHORT CIRCUIT, so that in all areas whether alternating current or direct current works under this system