Hi Folks,

I would like to preface this post by saying that I have done a few hours of research on the forum but I still have some questions regarding the use of relays with lighting applications. Pictures are great for answering "what" but don't quite answer questions regarding "why" and to some extend "how". I have a '00 Super Cab 4x4 and I plan on installing 2 or 4 Led Lamps behind my grill.

What are the pros and cons along with the practical applications for both...... using relays and not using them?

Thanks,

Dave

 

No con's with relay's besides a couple extra wires to run. They're very simple to use and they allow you to control all the current (power) in the relay instead of having to snake a power wire all the way threw the truck, run it through a switch (which has to be big enough to handle the amp load of the lights) and then back to the lights. But relay's are almost a must for high current applications such as many lights because most switches can't handle the load of the lights and can pose safety hazard's such as fires.

Basically the relay has 4 pins on it. One takes a hot wire in (from the battery). Another passes the power to the lights. Another pin for grounding the relay. And the last is a switch pin. Basically you run a single wire off the relay to a switch, whether it be a switch in the cab that you can control or hook it up to something else such as your high beams so the lights will only come on with your high's. The lights will stay off until current is passed through the switch wire which then closes the relay and your lights come on.

This probably isn't the best description ever but there's plenty more people on here who will be able to elaborate on this.

EDIT:
Just found this on google
http://www.lunghd.com/Tech_Articles/...elayBasics.htm

Could be pretty helpful for you.

 

Thanks PizzaMan. I actually started to send you a PM about this based on the level of knowledge and help you provided me in my other thread. Also tried to rep you, but didn't find an option for that. Just know that if I could I would.

 

Hi OP;

All y'all ever need to know: http://www.the12volt.com/relays/relays.asp


And from our own Tech Articles section:

https://www.f150online.com/tech/electrical1.html

https://www.f150online.com/tech/control1.html


Additionally, if'n yall run into trouble, look these fellers up - they can hep yall...

 

For your application of 2 or 4 LED light specific

Con = additional work and cost for no gain.

4 LED lights are going to draw < 1A, even the crappiest switch you can find will not have an issue with the contacts in this install.

A relay ( in automotive use cases ) is a low amp control of high amp load. It can drive 70A + of load ( with the correct sized relay ) with a < 1A switch contact rating. The coil amp draw is very small to keep the normally open contact pulled in. The device load is only across the normally open contacts.
some of the solid state relays for winches are 300A relays with < 1A of switch load.

I guess it really comes down to what is the AMP draw for each light head that you are installing, to know if it is required.

The pro for installing the relay day one for this, is when you get around to adding lights to the circuit, everything is already there for the expansion. If you know you are never going to add lights to this circuit, then there is no real gain to be made by using a relay.

The 52 LED Truke-lite back up lamps draw ~ 1A each light head.


This is what I would say is the pro & con to the information in your post.