I need to install a headlight relay in my T-Bucket (the original builder didn't install one). The only thing i know about electricity is if i touch the wrong thing it can really hurt and if it ain't done right it can make a really pretty fire. Do i need two relays (one for low beam, one for high beam)? Should it be wired in before or after the light switch? Does anyone have a simple wiring diagram?
Why? I've built about a dozen rods over the years and not a one had a relay. Now if you are running something that pulls a 100 Watts a lamp that is a different story.
Try this. Might need to load latest version of adobe reader to get it to open. http://www.antechlabs.com/K0GFM/LandingLites.pdf Or this one if you have a four light setup. http://www.antechlabs.com/K0GFM/RelayHeadlampWiring.pdf
Because headlights pull a lot of juice. When i turn the lights on my volt gauge drops from about 14 volts down to about 10.
On our '50 Burb, I relayed the low and hi seperately. (two relays). Keeps the heat out of the switch, and doesn't pull so hard on the delayed park light module. Sounds as though you have other issues - weak battery or alternator.
A bit small but should work. If you want you can relay high and lows seperatly. Just put a relay in line from each of the dimmer switch outs instead. Dim lights, high draw, check connections and grounds. At 12V 2x 35 watt low beams should only be pulling 6 or 7 amps, if my ohms law math is correct.
relays kick ass. I use them for anything and everything that takes a lot of juice. It takes the load off the switch (headlight) and you'll probably get brighter headlights to boot. I run them for headlights, elec fans, a/c, amp, horn
I think you have some other electrical issues to be losing so much voltage by turning on your headlights. In the mean time...for me, relays are there to serve a purpose...not just to "have a relay" in the circuit. The vehicles I've converted, I used the relays to get as much voltage to the load (lights in this case) as possible. The relays go as close to the load (lights) as possible and use the original wiring as a switch wire. A new large gauge wire (10g or even 8g) is tapped right off the batt positive or from the main junction stud at the firewall (if it itself has the required voltage and low resistance current source available). This wire provides full voltage to the lights once the relays are tripped. Result...in this case brighter headlights, especially if you upgrade to Halogens or some other type that can make good use of the extra voltage. Simply having a relay between the stock headlight switch and the fuse panel will do nothing to improve your lighting performance as the voltage will still be passing thru the original wiring and switch for distribution to the headlights. Zero gain. I did a 57 Chevy for a friend who had put in halogens to SEE where he was going, but they were only a minor improvement. He was really bummed out and pretty much limited his driving to daylight due to his lack of confidence in the lighting. Relays had him raving about the Halogen upgrade. I was shocked at how small those Chevy headlight wires really were! I can't imagine someone doing their own wiring would use such light gauge wire, so in that case the difference might not be as dramatic.
"Simply having a relay between the stock headlight switch and the fuse panel will do nothing to improve your lighting performance as the voltage will still be passing thru the original wiring and switch for distribution to the headlights. Zero gain." True, However, You need to mount the relays near the lights and run a large gauge wire directly to the relay and lights with circuit protection. The stock wiring can be used to activate the relay. This will give an almost negligible voltage drop at your headlights. On my O/T Mustang you lose almost 2 volts going to the dash and back leading to nice brown lights plus the old switch's circuit breaker is weak and cannot carry the load of newer halogens. A lot of people just change to a new switch but adding relays will save the hassle and money as the relay won't load the circuit breaker like the bulbs. I used circuit breakers scavenged from a newer car ( 88 Mustang A/C C/B) They plug in like a mini fuse and I just plugged them into an inline fuse holder before the relay load side.
Probably for the same reason I need a pair on my 71 GMC Bright Halogen lights that draw more juice than the light switch and dimmer switch want to handle and hold up. The dimmer switches in my truck don't last long with my 55/100 watt lights that I run. But I can see the drunks wandering up the road at 0400 am on foot in plenty of time on my way to work.
Yep with large draw lights ya need a relay, had aircraft landing lights in my Vette in the 60s . Dang headlight switch made like a turnsignal flasher. But the OP has some other prob if his voltage is dropping from 14 to 10 with the lights on. Millions of car were made without relays with no problems .But they did not have the high draw lights available that we have today either. Still in most cases a relay isn't really needed.
True...however??? Ahhh...Virgil...what you said is exactly what I SAID (other than using protection!) in the previous paragraph to your quote! LoL
a short (Yikes!) note-not all relays are made the same-make sure you get the right one for the right appilication
It's good to use protection! Your right, I reread your post, it was not my intention to impune your fine post Suh!
Well thats quite alright sir...think nothing of it! I wonder is the OP using a single wire Alt? Seems really weird to be dropping that much voltage. THATS the issue should be addressed...not relays first. I'm really puzzled about what he has going on... I doubt the Alt is dead if he's getting 14+ volts with the headlights off. I like to pull relays and plugs from OE applications...like 80's/90's Dodge Caravans that have them high on the drivers side of the engine compartment for easy snipping. The OEM stuff seems to be of excellent quality compared to the small Bosch style relay. They ARE good...but I just like the OEM stuff myself.
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