Rusty, thanks for this. I didn't know of Daniel Stern's website before, lots of good info there, and a source for quality parts.
Well... There are problems and there are PROBLEMS. Systems without relays have worked for ages, and as long as they work as they should they can work well - they just (generally) cause a bit more resistance due to the longer wires, more connections and so on along the way. This reduces the voltage that reaches the lamps, and reduce the light output (as well as it makes the lamps last longer). If you see good enough despite the voltage drop you are likely to have in such a system you don't ha ve a problem. You have less light than you could have, but if you don't miss the extra light it doesn't qualify as a problem. Perhaps you only drive in daylight? On the other hand, if you drive at night and would like to see better, any voltage drop between generator/battery and headlights IS a problem, as it reduces the light output. It takes a few minutes to start the car, measure the voltage at the battery after a moment (when it has stabilized after the load of starting the engine), and then measuring the voltage at one of the headlight lamps - straight ON the lamp connectors, with it still installed. Any voltage difference tells you you are loosing light. Then, the PROBLEMS... They often come with a burnt smell. They're kind of obvious, when something has gone wrong.
Headlights are super sensitive to any voltage drop in terms of lumens or bulb output. It falls off a cliff with even just a few tenths drop in the wiring, connections, or grounds. So if you restore the grounds and connections you'll see much better. The same is also true for ignition and accessories, though not as noticeable as lighting. The first thing most people do is install a set of halogen bulbs, which aren't any better without the juice they need. If the grounds and cables and frame connections (and generator output) are within spec the lighting will be acceptable. Adding relays will take the load off the switch and improve lighting. I didn't notice a dramatic difference adding relays in terms of distance, probably because everything was already squared away, what I did find was there most definitely increased lighting to the sides. Road signs and markings are lit up better. It also seems to improve the tendency for generator equipped vehicles to dim somewhat at idle or just off idle. Generator systems are different from alternators in that the battery is the sole provider for juice at idle.
Greetings guys and gals, as indicated in my profile I’m new to older cars wish I knew more about mechanics and how to work on them, i’ll learn, I’ve had like 20 Harley Davidson‘s 40 cars so I’ve worked on small things maintenance but when it gets into electrical and installing gauges and motor parts That’s where I don’t trust myself at all. I know this is an old thread but my question is, this car that I bought although it’s a 1940 street rod business coupe, the build is only about 9000 miles old originally were not originally but the motor that was put in at 9000 miles ago was a new 350 crate V-8 has a three speed Automatic transmission, all the lights seem to work on it it has a CD AM/FM 4 speaker stereo in it, end up front it has the 7 inch sealed beam headlights, the only thing that seems to work a little slow or the windshield wipers and that’s an easy enough fix from what my son told me. My question is I wanted to do something very simple that I can do it looks like I could just take a aftermarket 7 inch halo light for instance that has just one plug on it that would plug directly into where the current sealed beam is and everything would work. that said with this being a modern build would you think there’s any reason to add anything different to the car if I added those lights it’s a 12 V system of course alternator air conditioning fuel cell electric fuel pump.
I have a related question about relays if I may. The question concerns positioning of the relay(s). Does this matter at all? Logically I'd say no, the electrical current won't know where the relay is, but would welcome advise. Looking at say a '32, I'd prefer the headlite relay(s) to be hidden somewhere, ideally under the dash, such that the wiring looks as normal as possible plus the problem of trying to hide the relay(s) somewhere in the grille shell area is eliminated. Similar concerns with fan relay (non trad) and even fuel pump. In the headlite example I realise there would need to be 2 heavy feed wires (hi/lo) instead of just one (to relay) if the relay was in the grille shell or thereabouts. Thought? Chris
A protected location is always good, water and dirt isn't good for anything electrical. Other than that it shouldn't be anything but the basic common sense: the longer wires you need to use, the more resistance there will be in them and the bigger the voltage loss will be.
When I changed my lights from standard seal beam to halogen I had to add relays to power the lights. Otherwise the GM type switch could not handle the load and the lights would switch on and off while driving. On my 32 I put the headlight relays up under the dash, not far from the headlight switch. I have one feed wire from fuse panel to feed both hi and lo relays. My fan relay is on my electric panel behind the seat. My carter electric pump only draws four amps, so it has no relay. Just a 30 amp toggle switch that I use to prime the carb. Hope this helps. Phil
Just a note, I am using a mid 1960's Volkswagen locking relay for a dimmer switch. It looks like a Bosch relay, but each time it is grounded it switches between low beam relay and high beam relay. I can provide part number and wiring details to anyone who messages me.
Thank you I think I’m gonna leave the sealed beam headlights and place the bumper on the front of my car was removed so the local stereo shop that has been around for 30 years and I’ve done all my lights and window tinting and stereo stuff I got a put 25 inch LED headlights were those holes for the bumper was so I’m sure they’re just gonna wire that separately that she looked pretty cool I got a hole in the dash right for a switch thanks Sent from my iPhone using H.A.M.B.
I I don't understand the function of the first relay. Wouldn't the circuit work with just the second relay?
I used old Standard Ignition LR 34 on my cars. Just don't tighten the cover screw too much, it will pull up on the point block.
Since the use of a relay is to restore the voltage lost with wiring and switches , wouldn't it be advantageous to locate the relay as close as possible to the load ? Seems to me that they used to be mounted to the radiator support ??
The purpose of the relay in this case is lighten the load on the switch, hanging them o the radiator support you would want to switch to sealed or water proof relays.
I have an o/t '60's car, it didn't even have halogen lights and the lights would sometimes flicker at night due to the headlight switch overloading. I put two relays on the radiator support but behind the headlight out of the weather, and upgraded to halogens at the same time. Best thing I ever did to that car.
If you use 12 Gauge wire for ALL the replacement wiring, the wiring voltage drop is minimized and the relay location is not important (see above comments about weatherproofing). EDIT: See the post below this post - The wiring diagram summarizes the above discussions - One criticism - The 50 Amp fuse is to big for 20 Gauge wire - A 20 Amp fuse (25 Amp maximum) for this wire gauge.
For relays to be effect, the power source must come right off battery and be a heavy wire. The longer the wires, the heavier they need to be. The dimmer switch turns relays on and off suppling the head lights with direct from battery power. Headlamps should also have a dedicated ground wire to battery or frame, not sheet metal.
A 6014 bulb draws 3.5 amp why would you possibley use a 50 amp fuse or 12ga wire? Factory setups use 10 amp fuses for headlights Why use 2 relays when the 5 prong relay was designed to be a hi/low beam relay in the first place? There is not a lot of draw on these circuits the most common issues are poor connections and old headlight switches with poor internal connections. I believe the original op just wants to move the dimmer switch up to the dash and use the blue internally illuminated switch, unfortunately the switch does not have the amp capacity for the the circuit without using a relay as a buffer.
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