WHY USE RELAYS?
Those are long lengths of thin wire between the battery and the headlamps! Most such circuits produce unacceptable voltage drop. To bring full power from the electricity producer–the battery or alternator Positive (+) terminal–to the electricity consumer–the headlamps–we must minimize the length of the power path between the producer and the consumer, and we must maximize the electrical current carrying capacity, or wire gauge, of that power path. But we still want to be able to control the headlamps remotely (from the driving seat), so how do we do that? Install relays! A switch is a device that completes or breaks a circuit, sending or interrupting current to whatever device we wish to control. A relay is simply an electrically-operated switch. When we send power to the relay with the headlamp switch, the relay completes a circuit between the the battery or alternator Positive (+) terminal and the headlamps. Unlike headlamps, relays require only a tiny amount of power to operate,
