Hello

How fuse work 80A 20A work does battery give differrnt current

Could you rephrase the question and supply more information?

On 1/30/2022 at 12:19 PM, Johnn said:

Hello

How fuse work 80A 20A work does battery give differrnt current

Yes, a car battery voltage is standardised at 12v, but the current depends on the resistance. ( I = v/r )

If the resistance r becomes too low, for example if there is a short circuit, the current will rise very high, and could potentially cause a fire. So a fuse is put in the circuit that is designed to melt at the nominal amperage, as in 80A or 20A. That breaks the circuit and avoids the fire risk. 

The same principle applies in house wiring, but with a different voltage.