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Relay, Fan, 40 Amp, Single Pole, 48 in. Wire, Each. Relay and Harness, 40 Amp, Single Pole, 12 in. Wire, Gauge, Each. Relay, 40 Amp, Single Pole, Kit. Low Price Guarantee. We're so confident in our low prices, we offer a Beat-a-Price Guarantee: We'll beat our competitors' advertised prices on any identical, in-stock product proof of advertised price required!
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Promoting, selling, recruiting, coursework and thesis posting is forbidden. Students Click Here. Related Projects. Everywhere else in the electrical world, electrical components come with amperage ratings on them. And the electrical specifications of the component is printed on the product packaging or there is an insert with specifications on it.
And this information is on the manufacturer's web site. But NOT with automotive parts! Nothing but a part number on the packaging for switches and relays. No part specifications on the internet anywhere! Automobiles are becoming quite complex electrically and technicians need to know this basic information. Anyone know where to find electrical specifications for automotive switches and relays? Or is there a particular automotive parts manufacturer who has "joined the internet age" and has this information on their web site for their parts?
Here is an example of typical relay specifications from parts suppliers "in the rest of the electrical world" Are you just talking about walking into an auto parts store or something? There's typically 2 levels of parts available. Junk unrated ones and good rated ones.Display Options.
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Relay, 70 Amp, 12 V, Stock, Each. Relay, Ford, Kit. Standard Relay.
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International Customer Options. Delivery Options If you are an international customer who ships to a US address choose "United States delivery" and we will estimate your ship dates accordingly. International delivery. United States delivery. Recent Vehicles. Refine results by: Current Vehicle Recent Vehicles.Wire uses the measurement of gauge to determine the size of the wire. The larger the wire, the smaller the gauge number. To find the required wire gauge for a specific application, you must know the current draw of the accessory on the circuit and the total wire length between the accessory and the power source.
More current draw higher amperage requires a larger wire gauge to safely power the accessory. Automotive wiring is not exactly 12 volt. The actual resting voltage of a fully charged, 6-cell automotive lead acid battery is about Older batteries will probably show a lower voltage. When the vehicle is running, the alternator will increase the automotive voltage up to about With cable length comes resistance.
All wire has inherent resistance and the longer the wire, the greater the resistance and the greater the voltage drop over the length of wire. For that reason, it is important to factor in the length of wire when determining the wire gauge.
A 3-foot wire length will have less resistance than a foot wire and therefore a longer length of wire may require an increase in the wire gauge to provide adequate voltage to the accessory. Installing too small a wire gauge decreases performance and may create a potential safety hazard. Alternately using an oversized wire gauge does not have a downside and may provide better performance of the accessory, however, overkill in itself has the downside of wasted money and valuable space. To choose an adequate wire gauge, determine the amp draw amperage that the wire circuit will carry.
Then measure the distance that the wire will travel length including the length of the return to ground the ground wire running to the chassis or back to a ground block or battery.
Using these two numbers, Amps and length, locate the nearest gauge value in the chart below. For 6 volt automotive systems typically a wire gauge 2 sizes larger than what is shown should be used. Using LED lights in your Vehicle. What are HID Lights? There are good reasons for this. LED lights consume about 10th […]. Thank you for your efforts. The sizes recommend seem conservative and safe. Scott P. I was struggling to find info on very short runs of cable.Connect with us.
Electronics Forums. Reply to Thread. Search Forums Recent Posts. Scroll to continue with content. Mar 2, 1. How do you find the amp rating on a 12v relay? I have several. Mar 2, 2. Usually you just Google the query and get the data sheet for the relay or the range of relays where all those details are listed.
Mar 2, 3. This PDF generally applies to all Automotive simple cube relays and gives an idea of filament resistive or motor inductive load. Mar 2, 4. What I have learned over the yerars having similar issue is simple: Just write down the unit name, brand, etc. That is of course - if it was used in some device when you found it. Pokey likes this. Mar 3, 5. Hello, this is my first post.
12 Volt Automotive Relays
Please be kind. Relay switches. I believe it is written on the SPDT relay switch. Usually 12 volts on car radios. One pole, or input, two outputs to an input connection. Mar 4, 6. Mar 8, 7. If you know it is a 12v automotive relay, then why would you need to know the amperage?
Then your relay might only require a few amps to fire. But there are very few auto manufacturers who would put a small relay in because it is possible for power surges, or mechanical errors that could allow high amps through You must log in or sign up to reply here. Show Ignored Content.
Ask a Question Want to reply to this thread or ask your own question? You'll need to choose a username for the site, which only take a couple of moments here. After that, you can post your question and our members will help you out.A relay is an electrically operated switch. Many relays use an electromagnet to mechanically operate a switch, but other operating principles are also used, such as solid-state relays.
Relays are used where it is necessary to control a circuit by a low-power signal with complete electrical isolation between control and controlled circuitsor where several circuits must be controlled by one signal.
Relay Module - AliExpress. Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. Start by removing the Plastic or PVC case of the relay by using a screwdriver. You can see the design and various parts of the relay. A simple electromagnetic relay consists of a coil of wire wrapped around a soft iron core, an iron yoke which provides a low reluctance path for magnetic flux, a movable iron armature, and one or more sets of contacts there are two in the relay pictured.
The armature is hinged to the yoke and mechanically linked to one or more sets of moving contacts. It is held in place by a spring so that when the relay is de-energized there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts in the relay pictured is closed, and the other set is open.
Other relays may have more or fewer sets of contacts depending on their function. The relay in the picture also has a wire connecting the armature to the yoke. This ensures continuity of the circuit between the moving contacts on the armature, and the circuit track on the printed circuit board PCB via the yoke, which is soldered to the PCB.
When an electric current is passed through the coil it generates a magnetic field that activates the armature, and the consequent movement of the movable contact s either makes or breaks depending upon construction a connection with a fixed contact. If the set of contacts was closed when the relay was de-energized, then the movement opens the contacts and breaks the connection, and vice versa if the contacts were open. When the current to the coil is switched off, the armature is returned by a force, approximately half as strong as the magnetic force, to its relaxed position.
Usually this force is provided by a spring, but gravity is also used commonly in industrial motor starters. Most relays are manufactured to operate quickly.
In a low-voltage application this reduces noise; in a high voltage or current application it reduces arcing. When the coil is energized with direct current, a diode is often placed across the coil to dissipate the energy from the collapsing magnetic field at deactivation, which would otherwise generate a voltage spike dangerous to semiconductor circuit components.
Some automotive relays include a diode inside the relay case.One Big Relay, 120 Amp Relay / Battery Isolator
For instance when a relay switches in your car the voltage spike can cause interference on the radio, and if you have a faulty battery or are silly enough to disconnect it with the engine running it can damage the ECU etc. IMAGE: 1.
Circuit symbols of relays. Since relays are switches, the terminology applied to switches is also applied to relays; a relay switches one or more poles, each of whose contacts can bethrown by energizing the coil in one of three ways:.
Normally-open NO contacts connect the circuit when the relay is activated; the circuit is disconnected when the relay is inactive. It is also called Form A contact or "make" contact.A car relay is a electro-magnetic switch that uses a small amount of current to control a larger amount of current.
How they work is by a wire wound magnetic coil that when excited by a electric current, moves a mechanical spring contact inside the relay, completing a circuit. Relays are located all over a car, truck, van, suv or hybrid. They are placed in the engine compartment, fuse box or fuse panel, under the dash board or behind door panels and kick panels.
Check your owners manual or service manual for exact placement. The most common relays used to control electrical accessory devices in the automotive industry are ISO Mini and Micro relays. Normally open or normally closed types. Look for relay diagrams or a relay schematic that is printed on the side of the relay to determine it's function. Below are some examples of basic 12 volt DC car relays. Note: In a basic or resistor protection relay, pins 1 and 2 of the micro relays and pins 85 and 86 of the mini relays can be interchanged positive or negative.
Look for a relay diagram or a relay schematic that is printed on the side of the relay to determine. Diode Protection For A Relay 4 pin mini shown Resistor Protection For A Relay 4 pin mini shown Current flowing through a relay coil creates a magnetic field which collapses suddenly when the current is turned off. The sudden collapse of the magnetic field induces a brief high voltage across the relay coil that wants to flow in the opposite direction which can cause damage to a ECMPCM or ICs.
A quenching protection diode or suppression resistor allows the induced voltage a path to block and dissipate. This prevents spiked voltage becoming high enough to cause damage to a electronic control module or a IC.
Automotive Accessories Connection. Your car, truck, van, crossover, suv and auto accessories dealer on the web since Anything on our web site is quoted in US government dollars.
Currency Converter. Quantity discounts available. Copyright:,, Case size: 1 inch x 1 inch x 1 inch Pin Power into the relay for the accessory device Pin Relay switched power out to the accessory device Pin Positive hot line to activate the relay coil Pin Ground line to the relay. Case size: 1 inch x 1 inch x 1 inch Pin Power into the relay for the accessory device Pin Relay switched power out to the accessory device Pin 87a: Powered hot when relay is at rest.
Open when relay is activated Pin Positive hot line to activate the relay coil Pin Ground line to the relay. Open when relay is activated Pin 2: Positive hot line to activate the relay coil Pin 1: Ground line to the relay.