Relays

Hey guys I planned on running relays in my headlight circuit but the fellow who runs the hotrod shop says that i dont need to run them. My fathers an electrical engineer and explained to me about relays and it makes sense to use them. the likes are 60watts each

 

Not absolutely necessary but it is much better to use them.

 

Technically, relays are to switch heavy current near whatever is consuming the power. This allows the use of lighter wiring to and from switches, etc. It can also prolong the life of switches by having them control only the very low current needed to trigger the relay. Might be useful if you had a rare, hard to find a replacement switch, but for what you are doing, sounds like overkill.

So, your dad is right, but I wouldn't bother for the loads you mentioned.

 

Pay attention to Dad! check this out: www.watsons-streetworks.com/current_topic.html this is a great explanation of relays with diagrams,I bought mine from them(not Chinese junk) also the 70 amp relay for the ignition switch is a good security investment.

 

I get genuine Ford relays made in Canada 10 for 20 bucks from here:-

http://www.allelectronics.com/make-a-store/item/RLY-455/12VDC-AUTOMOTIVE-RELAY/1.html

 

2 big thumbs up for the relay. Lets you run itty bitty wire and switches inside the car. Keep the heavy gauge to a minimum and only from Batt to lights...

 

No relays, on anything; Buss power through an inline fuse direct to the resistance, return line to switch, switch direct to ground; Cost of supplies is less without, fewer components, fewer connectins, just make sure the control switchs and wiring are rated to carry the load. Big-***ed high capacity switches look good to me. Troubleshooting is a no-brainer.

 

Yep. K.I.S.S.

 

MY TWO CENTS---

Relays can be great but they are one more failure point. K.I.S.S.
Keep.It.Simple.

If you can run a decent size wire and decent size switch, stay away from relays.

If you have to run something heavy, and your switches and wires are NOT heavy, then you have no choice but to run a relay (fans etc).

ANY TIME you have to use a relay, you are adding one more weak link trouble spot in your chain.

If all you have are those flimsy aftermarket toggle switches sold at parts stores, Ace, Radio Shack, and usual places, you NEED a relay or they won't hold up to much. If you can get the tougher switches with a decent amp rating, like they sell at implement stores, tractor supply, etc., then you are better off without a relay waiting to fail.

I have had relays fail before. Electric fans stay on until the twin batteries run completely down.... High beam stays on..... etc. Fans refuse to come on... Lights won't come back on... Trailer turn signals die due to relay failure...

I have never had that happen with simple switches. I understand a small temp sensor needs a relay to run the heavy fan current, but for lights and most other things, you are MUCH better off running sufficient size wires and sufficient size switches.

 

I have elect fan on one of my 'rods. I don't even need a relay to tell my fan when to come on. The day I can't keep up with turning that on, I'll quit drivin'. He, he. ....................