Running headlights through relays

rumrumm · May 17, 2018, 11:43:56 AM

My headlights are not as bright as they should be. I am running King Bee headlights with halogen lamps. A street rodder acquaintance of mine suggested running my headlight wiring through relays. Will that make that much of a difference in terms of brightness?

kb426 · May 17, 2018, 12:50:25 PM

Possibly. I ran all of mine with relays to lessen the load through the ignition switch. I had read that halogens could draw as much as 30 amps.

WZ JUNK · May 17, 2018, 01:02:28 PM

Easy test would be to add a relay in the main power to the dimmer switch. I have done this a couple of times on friends hot rods. It helps, but the real problem was the night vision of the driver.

John

348tripower · May 17, 2018, 01:18:20 PM

I had to do put relays in both the high and low beams of the COE. Seems the LED headlights would not work properly with out them. Truck Light where they came from said they should work with out them.

Charlie Chops 1940 · May 17, 2018, 04:07:41 PM

I've done my last 3 cars with full 12v directly from the alternator to relays for each beam. Fused the 12V lines to the bulbs. Mount the relays as close as possible to the lights themselves. In my case they went in the engine compartment just behind the core support I used Halogen bulbs and was really pleased. The best was the change to my old convert which used Cibie Halogens with better optics. Paired with LED taillights the car became visible and I could drive it comfortably at night. Has brights from hell.

When I did the Convert I got most of the stuff from a guy out on the web who has wiring diagrams and a ton of info on his web site. I'll see if I can find him and add the site.

https://www.danielsternlighting.com/tech/relays/relays.html

PeterR · May 19, 2018, 01:02:51 AM

Quote from: "rumrumm"My headlights are not as bright as they should be. I am running King Bee headlights with halogen lamps. A street rodder acquaintance of mine suggested running my headlight wiring through relays. Will that make that much of a difference in terms of brightness?

Before embarking on any wiring modifications, check the condition of the lamp ground wire and its connection to the vehicle body. Lighting problems are often caused by poor grounding.

https://www.danielsternlighting.com/tech/relays/relays.html

A couple of comments regarding the lighting circuit shown in the link.

If there is a fault condition anywhere along the relay feed or the wiring between the relay and the lights, the fuse will blow and leave the driver without any lights. This could be disastrous while driving at night on a poorly lit road.

Rather than a fuse, it is better to use a self-resetting circuit breaker. In the event of a fault, the breaker will quickly cycle on-off preventing major meltdown while still providing intermittent bursts of light while the vehicle is brought to a stop.

Power for lighting relays should be taken from the positive battery post rather than the alternator terminal. The battery will provide a more consistent voltage leading to longer bulb life.

While it is preferable to replace the wiring between the relays and the lamps with a heavier gauge, just eliminating the long run of skinny wire from the battery to the light switch then to the hi-lo switch and along to the front of the car will make a huge difference; and also increase the life of the switches.

38HAULR · May 26, 2018, 05:17:14 AM

Pretty much agree with your comments Peter . With fusing though I query the cct breaker vs fuse benefit . If there is a short the reset time will be very short . I would fuse each side both hi/lo separately .In this case one is better than nothing . I had an FE Holden with the a cct breaker inbuilt to the light switch ,these were factory ,and the contacts or the bi metallic strip was so weak ,the lights would be intermittent on a bumpy road . I am familiar with another cct breaker problem that I struck in my old 46 Mercury . The vehicle would simply shut down from time to time ,and flicking to neutral and coasting I could restart ,pretty scary rolling along in traffic on a freeway . This went on for months as I replaced an ignition switch[Toyota steering column] along the way. I could not find any loose connections . One summer day ,sitting at traffic lights she stopped running . Luckily behind me were fellow rodders who helped push the vehicle off the road . I ended up hot wiring the coil to the battery and drove home ,determined to fix it . I "stressed " the ignition system by disconnecting the +ve coil terminal wire that comes from the ign switch and loaded it with a headlamp and switched the ignition on . The lamp burnt for a while ,so I switched the wire to high beam to load it more ,very quickly it shut down . I turned the ignition off . Sat behind the wheel ,uncovered the wiring panel in the console that had no fuses ,all circuit breakers . Flicked on the ignition switch on ,the light worked and shut down ,and a faint "click" . It was a circuit breaker . Whoever wired the vehicle had wired the ignition system through the heater/aircon circuit breaker :evil: I replaced the breaker and rewired the ignition to "unfused" status .

With regard to the feed wire for lighting I usually connect to the starter solenoid battery terminal . I have seen enough corroded wires at battery terminal add ons to form my practice of steering clear . I also relay start circuits on automatic vehicles . It is a long run of wiring from the neutral safety switch loop from ignition sw to starter solenoid . I had a hot start issue with one of my 66 Mustangs fitted with the non clapper starter motor ,the starter solenoid was inefficient with heat,not helped by old light gauge wiring. Used a relay to apply the "start" 12v and for 10 years it has not missed a beat.

PeterR · May 26, 2018, 07:49:42 AM

Quote from: "38HAULR"
I also relay start circuits on automatic vehicles . It is a long run of wiring from the neutral safety switch loop from ignition sw to starter solenoid . I had a hot start issue with one of my 66 Mustangs fitted with the non clapper starter motor ,the starter solenoid was inefficient with heat,not helped by old light gauge wiring. Used a relay to apply the "start" 12v and for 10 years it has not missed a beat.

Even a vehicle with manual trans benefits from a relay on the start circuit. The current drawn by the solenoid is quite significant. It punishes the contacts in the ignition/starter switch and on vehicles with a harness connector in the firewall the large current flowing through the connector (simultaneously in both directions) contributes to the deterioration of the connector body.

38HAULR · May 26, 2018, 03:52:13 PM

Makes good sense Peter . I never considered the connector part . Many would notice though that unplugging a firewall connector will show some pins with visible oxidization . With the switch . Easier and cheaper to simply plug in a relay than have to replace a switch that could have lasted longer than it did .

wayne petty · May 31, 2018, 11:04:39 PM

FYI...

when diagnosing electrical issues..

print and learn this test sequence.. https://i.imgur.com/kviX0VQ.jpg

i use it every day..

it is the first step.. not the last step.

you should continue if you are having headlight issues.. checking the positive voltage at the headlights with the other test lead on the positive battery terminal so you check the voltage drop.. if you have significant voltage drop.. check at the dimmer switch using a jumper cable hooked to the positive battery next to the car..

this is how to find resistance in the circuit.. resistance in a circuit is like somebody kinking your garden hose..

38HAULR · May 31, 2018, 11:39:57 PM

Quote from: "wayne petty"FYI...

when diagnosing electrical issues..

print and learn this test sequence.. https://i.imgur.com/kviX0VQ.jpg

i use it every day..

it is the first step.. not the last step.

you should continue if you are having headlight issues.. checking the positive voltage at the headlights with the other test lead on the positive battery terminal so you check the voltage drop.. if you have significant voltage drop.. check at the dimmer switch using a jumper cable hooked to the positive battery next to the car..

this is how to find resistance in the circuit.. resistance in a circuit is like somebody kinking your garden hose..

All handy Wayne . I find a common cause with deficient lighting is as already explained ,a poor earth . Another problem can be caused with older vehicles when lights get upgraded to Halogen for example, current draw is increased ,this then introduces loss in wiring of too thin a gauge that suited the older system ,or still a "lossy" earth connection now breaking down . The latter is more familiar to those who have experienced for example the loss of tail /brake lights when brakes activated ,even though the tail lights worked on their own and your switch is ok . The increased current is not handled by a poor earth of the socket to body ,or oxidization where the bulb metal body contacts the holder . .