Why and how to use a relay! They are Very Important

All right guys welcome back to Charlie's Garage. I just wanted to show you guys something. So we got most of the wiring under the hood and the pass through is complete and we got a couple things that we're going to clean up up here at the top which is going to be part of the larger rewire video. But what I'm getting ready to do is you'll see I got these wires right here that come off of things such as the electric water pump, the fans, and what these things need to do is need to run off of relays. And I'm getting ready to hook these relays up and I thought well maybe I should make a quick video about how relays work and why we need to use them. So we got these relays I got a whole package of them you can see the whole setup right here a whole bunch of them and then I got fuses for them too. So ultimately why do we need to use a relay? So a relay is a way of supplying a large amount of voltage or amperage I'm sorry to a load in order to get that load to work. So in this case our load would be that electric water pump right there these fans and if you try to power one of those items through just a regular ignition switch or a toggle switch or something like that you would overload that switch and potentially burn it up. So what you use the relay for is that the switch just tells the relay to close and the relay is what supplies the much more powerful current to the load in order to get it to function without burning it up. So the relay is basically taking the brunt of that instead of a weaker switch. And most of our relays work like this so if you take a look right here at this guy you can see it's got pins 85, 87A, 87, 30, and 86. So that means that it's a five position switch right here it's got five connections on it. Some of these will have only four and that's okay. So if we roll it back over and take a look what we're going to have is we're going to have power coming in from a switch and then you're going to have a ground and whenever that power comes in from the switch that is going to allow the connection between say the battery and then the other wire coming out going to the load. So that way your electrical functions like your fans and electric water pumps and stuff like that can get powered directly through this guy instead of through the switch itself. The reason why this is a five position switch instead of a four is because in a four you would have switch power in, ground, and then battery power in and then out to the load. On the five position switch the reason why we have that fifth one is so that you could have an alternate method of switching on and off this relay. So for example let's say I was operating my fans with this and I wanted my fans to be operated by a thermostatic switch. That switch would sense engine coolant temp and when the engine coolant temp reached a certain point it would send the power to this relay or provide a ground for the relay causing it to send power to the fans. But let's also say that I wanted access in the cab or in the case of my car inside on the dash a switch where I could turn those fans on and off anytime I wanted to. So that's why I would have a fifth one is if I wanted to have two different ways of activating this relay instead of just one way. I like to have the switch so that's why I got the five position. So my electric water pump and my fans are going to be both powered by a thermostatic switch and a switch in the cab. So for example I want my water pump circulating usually as soon as I start the car. I don't want to wait so I usually turn that switch on in the dash. The fans can wait until we reach to a certain temperature and then come on. But if I know I'm going to be in instant stop and go traffic I may turn the fans on in the dash right away so that the way they're operating already and I get a head start on the cooling. So that's kind of what's going on right here. All these wires over here that go I'm going to have to run through these and I'm going to mount them over there on that firewall. And then I'm going to have to braid them cable them zip tie them try to make them look pretty in the engine compartment. But like I said the actual wiring them and installing them is all going to be part of the larger wiring video that I'm working on. That video has been a long time in the making so when it finally gets done I'm going to be very happy because it's going to mean that this old girl is finally going to be back out on the road again. So if you have any questions about relays how to use them how they're wired please let me know in the comments and I'll be more than happy to explain and if needed make a video that goes more in detail on them. But around YouTube and Google there's hundreds of explanations about what each of these terminals do and how to wire them up so I would just be recreating everything and I wanted this to be more of a why you should use them rather than a how you use them. So again thanks for watching please subscribe let me know if you have any questions and have a good one bye.