relay

Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=131801
Printed Date: May 16, 2025 at 6:47 PM

Topic: relay

Posted By: cloves
Subject: relay
Date Posted: July 11, 2012 at 2:55 PM

Hi everyone,

New to the site, but I have been reading this site for awhile. Figured I would ask on here to see if someone could help be figure something out.

I have a ground switching circuit controller relay that I needed to change to a positive. So I went with another relay to convert the negative output to a positive output.

So I wired in the relay and its working. BUT I noticed that on Terminal 85 which is my negative trigger coming from the the controller relay, that it shows 12volts all the time until the negative trigger is activated. So my relay is feeding power back to the controller.

The relay has 12v coming into it via 30 and 86, now is it also normal for that 12v to travel out of pin 85 as well? I know once the controller relay give it a negative trigger, power exits out of pin 87, but I don't know if its suppose to show power exiting 85 all the time. So if you look at my diagram below, power is coming from the relay back up the (-) trigger number 85.

posted_image

Replies:

Posted By: KPierson
Date Posted: July 11, 2012 at 3:05 PM

The coil of a relay is a resistive device. Therefore, if you place 12vdc on one side of the coil and leave the other side "floating" you will see 12vdc on the other side of the relay. A relay coil has a resistance around 160 ohms which will effectively limit the current available through the relay.

Once your output activates and sends a ground signal to the relay and complete the circuit the relay coil will instantly become the load of the circuit and the 12vdc will no longer be on the other side of the coil.

Everything you posted is normal and shouldn't cause any issues.

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Kevin Pierson

Posted By: howie ll
Date Posted: July 11, 2012 at 5:08 PM

Or of course a diode across the coil, 86 to 85, 1N4004, band to 86.
That should stop the leakage.

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Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: KPierson
Date Posted: July 11, 2012 at 10:45 PM

Howie with the diode parallel to the coil it won't block the leakage. It will, however, stop any voltage spikes from the magnetic field collapsing.

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Kevin Pierson

Posted By: howie ll
Date Posted: July 12, 2012 at 1:29 AM

Ta Kevin, I live and learn, diode on the green? Band towards controller?
P.S. On a side issue, were the F/book paint colours Verizon?

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: howie ll
Date Posted: July 12, 2012 at 1:30 AM

Forget my comment, it won't stop the pos back feed either.
I'm great on the practical, terrible on theory.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: KPierson
Date Posted: July 12, 2012 at 6:15 AM

howie ll wrote:

Ta Kevin, I live and learn, diode on the green? Band towards controller?
P.S. On a side issue, were the F/book paint colors Verizon?

Yes, Verizon colors. We have another store set to open in early August!

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Kevin Pierson

Posted By: howie ll
Date Posted: July 12, 2012 at 6:18 AM

Mazeltov! I'm glad someone's bucking the recession trend.

-------------
Amateurs assume, don't test and have problems; pros test first. I am not a free install service.
Read the installation manual, do a search here or online for your vehicle wiring before posting.

Posted By: KPierson
Date Posted: July 12, 2012 at 3:59 PM

Thank's Howie.

Things in our area are doing fairly well considering. We were lucky to get a location in a brand new "high end" strip mall in a very nice area of town.

I'll post lots of pictures of the build out - it will feature quite a bit of interactive display technology - much of it created by my brother and me.

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Kevin Pierson

Posted By: cloves
Date Posted: July 12, 2012 at 5:39 PM

Guys thanks for the reply.

Do you guys think that the power coming out of the other side of the coil (pin 85) and going back up to my controller relay, will damage my controller? I am trying to make sure the derale controller doesn't get damaged.

Posted By: KPierson
Date Posted: July 12, 2012 at 5:51 PM

It's extremely unlikely that this voltage will even be noticed by the controller, assuming the controller is designed to operate a 12vdc inductive load. If you have any doubts I would contact the manufacturer. Most 12vdc outputs are designed to drive a relay so there shouldn't be any issues.

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Kevin Pierson