multiple led strips, relays, and switches

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=120840
Printed Date: July 22, 2025 at 6:05 AM

Topic: multiple led strips, relays, and switches

Posted By: scooter99
Subject: multiple led strips, relays, and switches
Date Posted: March 21, 2010 at 1:07 AM

Ok so here's the deal. I'm running numerous led strips in my car for my audio system. I have two zones, so to speak, the trunk and the cabin. They are both run by switches which are powered by the ignition of the car. Those switches then send the power to my relays. Then from there to the leds. I have the relays hooked up as follows.

87 - Power from the swtich

85 - Out to the terminals where the leds are connected to

86 - Ground

30 - 12v in from battery

Where am I going wrong here, and is this the best way to do this? Or should I be running the relay in front of the switches and then the leds?

Any help would be appreciated. Thanks!

Replies:

Posted By: the12volt
Date Posted: March 21, 2010 at 1:14 AM

Swap 87 and 85. Terminals 85 and 86 are the coil. Terminals 87 and 30 are closed when the coil is energized. https://www.the12volt.com/relays/relays.asp

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Posted By: scooter99
Date Posted: March 21, 2010 at 10:43 AM

I figued I had something wired wrong. There just seem to be sooo many ways to install a relay and I just got confused I think. Thanks I'll give that a go!

Posted By: howie ll
Date Posted: March 21, 2010 at 11:28 AM

Do we really even need relays here? Have you added the current draw on these strips? I bet they don't total more than 2-3 amps.

Posted By: scooter99
Date Posted: March 22, 2010 at 12:44 AM

I don't know if I do or not but I'm running about 8 12" strips and 5 20" strips and I think a couple smaller ones as well. Also will be adding more in the near future for other "show" features. I just wanted to make sure i didn't have any power issues.

I appreciate the help in fixing this. I swapped the wires and we're good to go. Everything is working. THanks!

Posted By: howie ll
Date Posted: March 22, 2010 at 3:05 AM

If you have time, take a DMM, set it to the 10 amps DC current (or 20 if it does that) setting, remove the output lead going to the LEDs from your rely, place the red meter lead to that terminal and the black meter lead to the wire you just removed.
Turn on the switch. The reading will give us the draw. I'd like to know whether you could have saved the cost and wiring up time of that relay!

Posted By: oldspark
Date Posted: March 22, 2010 at 6:37 AM

Onya Howie!

With each string usually 20mA, even 100 strings is only 2A.

But a strip - probably 6-8 2V (1.7V) LEDs in series or 3-4 3.4V LEDs in series, but multiple parallel strings....

So relays? Nah... maybe.... not for current anyhow.
But for independence of source (signal) voltage and current - as always - yes! (Compares to opto-coupler and driver circuitry...)
Oh - but relays are so "old tech"... (So are internal combustion engines and lead batteries. And electricity!)