|
An easy way to appreciate the value of relays is to think of them as switches that handle a lot of current while being controlled by switches that will pass only a small amount of current.
For headlights, as an example, you can ensure high voltage (reduced voltage drop) to your lamps if you power them with shorter (and higher gauge) wires directly from the battery (or as some prefer, from the alternator). But they must be controlled, so you use a relay to switch the lamps on and off. Most relays in cars can handle up to 30 amps or more. And you control these relays with your car's original wiring, which is lower gauge and longer paths (again, more voltage drop or resistance), but it doesn't matter because the current through the car's wiring is nominal (only a fraction of an amp).
In fact, if your car is a later model 240, it is notorious for having a headlight relay behind the front vents that is liable to burn out its socket, leaving you without low beam headlights. The use of relays to power your headlights eliminates this risk, because only minimal current will pass through the car's OEM wiring. See www.danielsternlighting.com for more details.
And on to the matter of foglights, similar to the headlights: If you don't use a relay, the wiring for the foglights, which as to be heavy gauge to carry enough amperage to the foglights, has to run from the battery to the passenger compartment where the switch will be located, and then back to the foglights. That's a long run (higher resistance) for wires! But if you use a relay, you can have short run of heavy wire from battery to fog lights, and run only light gauge wire to and from the switch in the passenger compartment, because that switch will only need to pass a fraction of an amp.
Hope this helped.
Happy Holidays.
|
