4.3LXJ
10-19-2012, 11:19 PM
This section can be used alone or with XJ TALK SHOW! Episode 51
This is intended as a visual aid to go with the Pod Cast
So what is a relay? To most it is a black box, a mystery. Never mind they are usually just little black boxes with some prongs that cannot be understood. Wrong! All they really are is a switch that can be run with another switch. They are just like the light switches in our houses, except that you don't operate them manually. We use an electrical switch to operate them. The most common ones look like this:
http://i649.photobucket.com/albums/uu215/warriorsuspension/images.jpg
These come in many configurations and I won't go into that here, but I prefer the ones with the mounting tab on them. Some don't have them and you generally have to specify that if you want one.
Here is a waterproof version that Painless Performance Wiring markets:
http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0488.jpg
So what is inside these little black boxes anyway? There are two parts, the contact points that are similar to the points we used for years in distributors and a coil that turns into an electric magnet when the power is applied and moves the contact points together.
http://i649.photobucket.com/albums/uu215/warriorsuspension/images-1.jpg
http://i649.photobucket.com/albums/uu215/warriorsuspension/images-2.jpg
So when do we use a relay? Anytime we need to provide a large amount of current to something that the factory wiring cannot handle. For instance, auxiliary driving lights, electric air compressors and electric cooling fans. For instance a pair of 55W driving lights pull about ten amps, the limit for most good switches. A pair of 100W lights pulls just under 20 amps. A Ford Taurus radiator fan, a popular upgrade pulls 37 amps running and up to 90 amps on start up. Our factory wiring was not designed to handle this kind of load. So we run extra wiring that will handle the load and use a relay for a switch.
So how do you wire these little boxes up anyway? It looks complicated. Not really. Here is a diagram you can go by.
http://i649.photobucket.com/albums/uu215/warriorsuspension/12527647e9129233622.jpg
You will notice these spades are numbered. You might need a magnifying glass to see them, but the numbers are there. This diagram shows a four prong relay. Normally we don't use the center one because it is connected until the relay is activated. It also typically is only rated at half the amperage the upper #87 prong. So if you have the type of relay with a mounting foot, and the foot is on the bottom, the power you want to go to your new accessory goes in the bottom and will come out the top. Not too bad. Then the power to switch will go to either side terminal and the other one will go to ground. Fairly simple really and once you have done it, it will seem simple. So what do we use for connecting to them? One of the common ways is to use crimp connectors that fit the spades on the relay. If you use these, there is two things you should remember. One is to get the kind that has the foot so you can anchor them down. You don' want any shorts. The second is make good crimps. Use quality crimpers. If you use cheap ones, they will not be tight enough and eventually cook themselves and ruin the relay too from heat generated at the connection. But there is a better way. Plugs are made to fit them. They look like this:
http://i649.photobucket.com/albums/uu215/warriorsuspension/images-4.jpg
These are nice because you get color coded wiring and it protects the prongs on the relay from contacting any metal and making shorts. The kind I use are commonly found at NAPA and can be hooked together with a dovetail joint so you can make a bank of them if you want. Here is my bank of relays for all my extra stuff
http://i649.photobucket.com/albums/uu215/warriorsuspension/2012-06-05_19-01-39_945.jpg
This image brings up a couple of points. One is the normal relay you get is rated at 57 amps. The plugs on the left are only for 40 amps. The plugs on the right that have the ten gauge wires are rated at 50 amps. You need to use plugs and relays that are rated for what you are using. And just because the plugs are rated for 40 amps, doesn't mean you can run 39 amps continuously on them. That rating is only momentary. I use a 75% rule, just as in residential and commercial wiring. A 40 amp part should not have any more than 30 amps continuous load. For instance, My Taurus radiator fan pulls 37 amps. In theory, the 40 amps should handle it right. Wrong. They will melt with about 30 minutes continuous use. But the 50 amp plugs allow me to run it continuously because 37 is right about 75% of the rating.
The second thing is, how do you fuse these things, especially for high amp use. I use circuit breakers. They are little two pole boxes at the left of the image. Here are the ones I used to replace my fusible links.
http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0694.jpg
Again get the ones with feet on them so you can attach them to something. The advantage of these is that you can get them in almost any amperage. The other is that if you have a problem, they reset themselves as soon as they cool off and can really be a big help finding problems instead of going through a box of fuses. Very handy in the middle of nowhere.
So what is another use for a relay? One we all take for granted is our starter relay.
http://i649.photobucket.com/albums/uu215/warriorsuspension/starter_motor_relay1_199c.gif
This is a relay that runs another relay. It takes power directly from the battery to run the starter solenoid, another type of specialized relay so that we don't have to have huge amounts of power coming through the ignition switch.
Hope you enjoyed the Pod Cast
This is intended as a visual aid to go with the Pod Cast
So what is a relay? To most it is a black box, a mystery. Never mind they are usually just little black boxes with some prongs that cannot be understood. Wrong! All they really are is a switch that can be run with another switch. They are just like the light switches in our houses, except that you don't operate them manually. We use an electrical switch to operate them. The most common ones look like this:
http://i649.photobucket.com/albums/uu215/warriorsuspension/images.jpg
These come in many configurations and I won't go into that here, but I prefer the ones with the mounting tab on them. Some don't have them and you generally have to specify that if you want one.
Here is a waterproof version that Painless Performance Wiring markets:
http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0488.jpg
So what is inside these little black boxes anyway? There are two parts, the contact points that are similar to the points we used for years in distributors and a coil that turns into an electric magnet when the power is applied and moves the contact points together.
http://i649.photobucket.com/albums/uu215/warriorsuspension/images-1.jpg
http://i649.photobucket.com/albums/uu215/warriorsuspension/images-2.jpg
So when do we use a relay? Anytime we need to provide a large amount of current to something that the factory wiring cannot handle. For instance, auxiliary driving lights, electric air compressors and electric cooling fans. For instance a pair of 55W driving lights pull about ten amps, the limit for most good switches. A pair of 100W lights pulls just under 20 amps. A Ford Taurus radiator fan, a popular upgrade pulls 37 amps running and up to 90 amps on start up. Our factory wiring was not designed to handle this kind of load. So we run extra wiring that will handle the load and use a relay for a switch.
So how do you wire these little boxes up anyway? It looks complicated. Not really. Here is a diagram you can go by.
http://i649.photobucket.com/albums/uu215/warriorsuspension/12527647e9129233622.jpg
You will notice these spades are numbered. You might need a magnifying glass to see them, but the numbers are there. This diagram shows a four prong relay. Normally we don't use the center one because it is connected until the relay is activated. It also typically is only rated at half the amperage the upper #87 prong. So if you have the type of relay with a mounting foot, and the foot is on the bottom, the power you want to go to your new accessory goes in the bottom and will come out the top. Not too bad. Then the power to switch will go to either side terminal and the other one will go to ground. Fairly simple really and once you have done it, it will seem simple. So what do we use for connecting to them? One of the common ways is to use crimp connectors that fit the spades on the relay. If you use these, there is two things you should remember. One is to get the kind that has the foot so you can anchor them down. You don' want any shorts. The second is make good crimps. Use quality crimpers. If you use cheap ones, they will not be tight enough and eventually cook themselves and ruin the relay too from heat generated at the connection. But there is a better way. Plugs are made to fit them. They look like this:
http://i649.photobucket.com/albums/uu215/warriorsuspension/images-4.jpg
These are nice because you get color coded wiring and it protects the prongs on the relay from contacting any metal and making shorts. The kind I use are commonly found at NAPA and can be hooked together with a dovetail joint so you can make a bank of them if you want. Here is my bank of relays for all my extra stuff
http://i649.photobucket.com/albums/uu215/warriorsuspension/2012-06-05_19-01-39_945.jpg
This image brings up a couple of points. One is the normal relay you get is rated at 57 amps. The plugs on the left are only for 40 amps. The plugs on the right that have the ten gauge wires are rated at 50 amps. You need to use plugs and relays that are rated for what you are using. And just because the plugs are rated for 40 amps, doesn't mean you can run 39 amps continuously on them. That rating is only momentary. I use a 75% rule, just as in residential and commercial wiring. A 40 amp part should not have any more than 30 amps continuous load. For instance, My Taurus radiator fan pulls 37 amps. In theory, the 40 amps should handle it right. Wrong. They will melt with about 30 minutes continuous use. But the 50 amp plugs allow me to run it continuously because 37 is right about 75% of the rating.
The second thing is, how do you fuse these things, especially for high amp use. I use circuit breakers. They are little two pole boxes at the left of the image. Here are the ones I used to replace my fusible links.
http://i649.photobucket.com/albums/uu215/warriorsuspension/IMG_0694.jpg
Again get the ones with feet on them so you can attach them to something. The advantage of these is that you can get them in almost any amperage. The other is that if you have a problem, they reset themselves as soon as they cool off and can really be a big help finding problems instead of going through a box of fuses. Very handy in the middle of nowhere.
So what is another use for a relay? One we all take for granted is our starter relay.
http://i649.photobucket.com/albums/uu215/warriorsuspension/starter_motor_relay1_199c.gif
This is a relay that runs another relay. It takes power directly from the battery to run the starter solenoid, another type of specialized relay so that we don't have to have huge amounts of power coming through the ignition switch.
Hope you enjoyed the Pod Cast