VintAGE-Vans

Would you like to react to this message? Create an account in a few clicks or log in to continue.

BRINGING IT ALL TOGETHER.... A's, G's & E's


+7
Axlejack
StuNami
kiwimopar
jrinaman
Big W
EconoCarl
DanTheVanMan
11 posters

    How to: Use Relays in Your Wiring Projects.

    DanTheVanMan
    DanTheVanMan
    Commissioner
    Commissioner


    Number of posts : 7900
    Location : Escanaba, Michigan
    Age : 62
    Registration date : 2008-10-08

    How to: Use Relays in Your Wiring Projects. Empty How to: Use Relays in Your Wiring Projects.

    Post by DanTheVanMan Mon Oct 10, 2011 12:44 pm

    How to: Use Relays in Your Wiring Projects.

    I used components available at “Summit” for this “How to:”


    An electrical system is only as reliable as its components. One easy way to increase system reliability and performance is by using relays to switch devices (lights, fuel pumps, fans, etc.) on and off. A relay is an electrode-mechanical switch. An electrode-magnet (also called a coil) is used to pull a set of contacts, or pins, together.

    Why not just use an ordinary on/off switch, you ask? Here are some reasons why relays are better than switches:
    1. A correctly wired relay will provide the shortest electrical path (i.e. shortest wire length) between the battery and the device(s) controlled by the relay. Combined with the proper gauge wire, this will minimize the voltage drop between the battery and the device, allowing it to function at peak performance levels.
    3. Relays allow you to use the proper size fuse for each device, and to place the fuses closer to the battery.
    4. If you use a vehicle’s stock wiring and switches to control aftermarket devices like high output lighting, relays will not overload or stress the OEM components. The average automotive relay can also handle a much higher current load than a switch (about 30 amps vs. 3-20 amps).

    Relay Types
    It’s important to know a relay’s pin configuration and function before connecting devices to it. Many automotive relays are similar in appearance and pin configuration and will plug into the same relay socket, but are completely different in the switching duties they perform.
    The most common type of relay used in automotive applications is the single pole/ double throw (SPDT). Also known as the Bosch relay, the SPDT has a common, movable contact that moves between two fixed contacts, termed Normally Open and Normally Closed. When the relay is off, the common and Normally Closed contacts are connected. When the relay is energized the common is switched over the Normally Open contact.
    Another type of relay is the single pole/single throw (SPST). The SPST is often found in the wiring harnesses for aftermarket lighting; it has a common contact and two Normally Open contacts that are internally connect. When the switch is activated, the contacts are connected.
    When power is removed from a relay’s electrode-magnet, a high voltage spike occurs. This spike can hurt on-board computers or other sensitive electronics. If your system has such devices, it’s a good idea to use replays with an internal shorting diode. The diode forces the voltage spike back into the electrode-magnet, where it dissipates as heat.
    Relays can help you make an electrical system perform better and run reliably. That’s why you’ll find them in most quality aftermarket lighting systems and wiring harnesses. Once you use them, you’ll wonder why you ever did without ‘em!

    How to: Use Relays in Your Wiring Projects. Fig_1c10

    This is the bottom view of a typical single pole/double throw (SPDT) Bosch-type relay, showing the pin configuration. Pin #30 is the common switch; it moves between pins #87 (Normally Open) and #87A (Normally Closed). Pin #86 is for the 12-volt positive lead, and pin #85 is for ground.

    How to: Use Relays in Your Wiring Projects. Fig_1a10

    This circuit diagram of an inactive SPDT relay with no power applied to pins 85 and 86 (ground and 12 volt positive). Pin #30 (common) and Pin #87A (Normally Closed) are connected.


    How to: Use Relays in Your Wiring Projects. Fig_1b10

    This diagram shows an active SPDT relay with power applied to pins 85 and 86. Pin #30 and pin #87 (Normally Open) are connected.

    How to: Use Relays in Your Wiring Projects. Fig_2a10

    This diagram shows how another type of relay, the single pin/single throw (SPST) operates. It has a #30 pin (common) with two #87 pins (Normally Open) that are connected internally. This type of relay allows you to wire two systems (such as a pair of lights) to activate at the same time.

    How to: Use Relays in Your Wiring Projects. Fig3ac10

    Here is a circuit diagram of a SPDT relay with a shorting diode. The diode prevents the voltage spike of relay deactivation from harming computers and other sensitive electronics.

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    Here’s some examples of proper relay use and uses.
    Electric Fan:

    How to: Use Relays in Your Wiring Projects. Fancon10

    When wiring an electric fan, make sure the positive ignition lead is one that turns off when the starter is engaged. You can use a thermostat housing that allows the thermo switch to be mounted after the thermostat. If you are installing an engine oil or trans fluid-cooling fan, you can mount the thermo switch in the engine oil or transmission pan.

    Fuel Pump:

    How to: Use Relays in Your Wiring Projects. Techec10

    When wiring an electric fuel pump, we strongly recommend using an oil pressure cutoff switch for safety. The switch cuts off power to the pump when oil pressure goes below 5 psi, protecting you from a potential fire. If you are using the pump to feed a nitrous oxide system, you don't need to use the pressure switch's N.C. terminal. Instead, wire a 12-volt positive lead from the nitrous arming switch to the switch's N.O. terminal. The pump is activated only when the nitrous system is armed.

    Auxiliary Lights:

    How to: Use Relays in Your Wiring Projects. Techec11

    This is a typical auxiliary lighting circuit. The second 12-volt positive lead from the on-off switch can connect to an ignition-activated system to give you manual control. For fog lights: connect the 12-volt positive lead to the positive wire on the parking lights. Connect the ground wire from the relay to the high beam positive wire so the fog lights will turn off when the highs are on. For driving or roof lights: connect the positive lead to the high beam positive wire, and the relay ground to the chassis. For auxiliary low beams: connect the positive lead to the headlight positive wire before it feeds into the high/low beam selector switch. This allows the auxiliary beams to be on when either high or low beams are on. If local laws require the auxiliary lows to turn off when the high beams are on, connect the positive lead to the low beam positive wire. The relay ground in both cases goes to the chassis.

    Upgrading Headlights:

    How to: Use Relays in Your Wiring Projects. Techec12

    This diagram is for using high-wattage bulbs with stock headlights. Upgrading to 80-100 watt bulbs definitely requires the use of relays. The relay system bypasses the stock headlight wiring, which isn't heavy duty enough to handle the increased wattage of the new bulbs. Make sure the ground wires for the new bulbs is at least 14-gauge. This system retains all stock light controls.

    Electric Water Pump:

    How to: Use Relays in Your Wiring Projects. Techec13

    A cool-down timer allows the water pump to continue circulating after the engine has been shut off to dissipate damaging engine heat. A timer setting of 5 minutes should be plenty for most engines. Make sure the band on the diode on the ignition wire (which prevents power from going back through the system when the ignition switch is turned off) is facing the relay. The timer is available pre-made, or can be made from a "555 Chip" available at your local Radio Shack.

    DanTheVanMan (2011)


    _________________
    DanTheVanMan    
    1965 Chevy G10 Sportvan Custom
    1984 Jeep CJ-7 Laredo, Restored
    2004 Kawasaki KLR650
    1997 Jeep TJ Sport

    My Mini Gallery

    How to: Use Relays in Your Wiring Projects. Qr_cod10

    <-<-<- Cruising is not a "Point A to Point B" thing, but an "Everything in between thing!  <-<-<-
    EconoCarl
    EconoCarl


    Number of posts : 1109
    Location : Beaumont, TX
    Registration date : 2008-05-19

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by EconoCarl Mon Oct 10, 2011 6:36 pm

    Dan, thanks for taking the time to do this write up. A lot of guys out there say "you need a relay" for this, that and the other and haven't got a clue as to how one works! I'd think this thread deserves a 'sticky'.
    Big W
    Big W


    Number of posts : 3282
    Location : Saskatoon,Sask,Canada
    Age : 60
    Registration date : 2011-01-13

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by Big W Mon Oct 10, 2011 10:08 pm

    cheers cheers Nice...thanks for that info. Wiring is not my strong suit, and that will help immensely
    jrinaman
    jrinaman


    Number of posts : 890
    Location : zelienople,pa.
    Age : 60
    Registration date : 2011-03-10

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by jrinaman Mon Oct 10, 2011 11:48 pm

    good info, thanks. busted one open last week to see what wires went where, next time i hook one up, i will just use your schematic
    kiwimopar
    kiwimopar


    Number of posts : 749
    Location : New Zealand
    Registration date : 2010-01-23

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by kiwimopar Tue Oct 11, 2011 12:08 am

    I am an electrician and I think this is a great write-up. Thanks Dan. Cool
    StuNami
    StuNami


    Number of posts : 437
    Location : Buckeye Nation
    Registration date : 2010-12-14

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by StuNami Tue Oct 11, 2011 4:43 am

    Thanks Dan. I'll be needing this info this week.

    ~Nami
    avatar
    Guest
    Guest


    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by Guest Tue Oct 11, 2011 10:35 am

    Great info. Thanks for taking the time to post it.
    DanTheVanMan
    DanTheVanMan
    Commissioner
    Commissioner


    Number of posts : 7900
    Location : Escanaba, Michigan
    Age : 62
    Registration date : 2008-10-08

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by DanTheVanMan Tue Oct 11, 2011 8:17 pm

    Received a PM from M1D and a pic of his pen drawing of the two relay setup he is using for his "Two Speed" fan asking if I could draw a schematic to share with all of you. This is a great basic schematic for anyone thinking about installing a two speed fan setup. This is a great addition to this thread... Thanks M1D!

    Dan

    How to: Use Relays in Your Wiring Projects. Dual_r11


    _________________
    DanTheVanMan    
    1965 Chevy G10 Sportvan Custom
    1984 Jeep CJ-7 Laredo, Restored
    2004 Kawasaki KLR650
    1997 Jeep TJ Sport

    My Mini Gallery

    How to: Use Relays in Your Wiring Projects. Qr_cod10

    <-<-<- Cruising is not a "Point A to Point B" thing, but an "Everything in between thing!  <-<-<-
    Axlejack
    Axlejack


    Number of posts : 49
    Location : Midland,Michigan
    Registration date : 2012-11-22

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by Axlejack Fri Dec 21, 2012 10:51 pm

    How nice to have this topic available on here. I have a much better understanding of relays and will be using them in my build. I was one of those guys to use manual switches but I can see the benifits from using relays. Thanks Axlejack


    Last edited by Axlejack on Fri Dec 21, 2012 10:52 pm; edited 1 time in total (Reason for editing : changed a word)
    wylee
    wylee


    Number of posts : 918
    Location : middletown,ny
    Registration date : 2009-04-03

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by wylee Sat Dec 22, 2012 3:05 am

    thank you dan.... you are one of many that keeps this site going.......
    RodStRace
    RodStRace


    Number of posts : 3046
    Location : Chino Valley
    Registration date : 2010-01-21

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by RodStRace Sat Dec 22, 2012 9:49 am

    Great writeup! cheers
    This should provide the info necessary to wire most relays properly.

    A couple things to keep in mind on your installation:
    Hide them in plain sight. This means that while they are much more reliable than straight wiring, there will come a time when someone will have to check/troubleshoot them. Try not to place them where it requires 20 minutes of component removal or working upside-down to access them!
    Also, even weather resistant ones should be placed to minimize water and dirt getting to them. VW famously placed a relay bank directly under a windshield drain in some cars. Yes, they had problems!
    If at all possible, use the same type and capacity relays for all your circuits. This way, you can remove the headlight relay and install it in place of the fuel pump relay and make it to the off-ramp or home. This should not mean you use an undersize relay, but plan ahead and have them all handle the same load.
    One final installation note - instead of wiring one like this so that is is difficult to replace,
    How to: Use Relays in Your Wiring Projects. Relays_med
    try to use the molded connectors at least,
    How to: Use Relays in Your Wiring Projects. Relays
    or even better, grab a relay bank from a modern car or aftermarket wiring company and modify it for your use.
    How to: Use Relays in Your Wiring Projects. 30107
    Buzzard
    Buzzard


    Number of posts : 90
    Location : arlington heights Ill
    Registration date : 2012-07-01

    How to: Use Relays in Your Wiring Projects. Empty Thank you

    Post by Buzzard Sun Oct 27, 2013 4:12 pm

    Finished rewireing my headlamps this weekend useing your post and a big difference in the amount of light my headlamps are now putting out. Running mustang high amp alt, low beams were were 12.05 and high beams were 11.89 volts with old wireing system. Now low beams and high beams have 13.89 volts running to them. Econoline owners Bumper to Bumper carrires Hopkins trailer extension (part #47965) which plugs into org headlamp assembly like it was from the factory. I cut the new harness in half and spliced it into the new relay system so now if i want to change it back no factory wires were cut and spliced. Now if a relay goes bad all i have to do is just replug back into the old system and i still have headlamps but not just as bright. Cannot belive the difference the way my Cebies are lighting up the road now, going to have to aim them a little lower now due to increase in light output.....Again a big thank you

    Buzzard

    i
    Space Truckin
    Space Truckin


    Number of posts : 1279
    Location : Upland,Ca
    Age : 68
    Registration date : 2009-10-17

    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by Space Truckin Sun Oct 27, 2013 7:11 pm

    Very Excellent Gentlemen,

    Thank you Shocked 

    Sponsored content


    How to: Use Relays in Your Wiring Projects. Empty Re: How to: Use Relays in Your Wiring Projects.

    Post by Sponsored content


      Current date/time is Tue Jun 25, 2024 9:28 am