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Put headlites on relays.

I don't mean to insult anyone's intelligence here but the thought occurred to me that some may not understand what a relay is and why it's a good idea to run relays for headlights on our older cars.

If you've ever seen a 50's or early 60's car at night you may have noticed their headlights seem to dim a little when the engine is idling, for instance at a red light. But when the light turns green they brighten up again when once the engine rpm is increases. Running relays solves this problem.

Now I'm not an electrical engineer, but here is my understanding of what a relay is. Just think of a relay as a high voltage switch. That's all it really is. It's an electrically operated switch that uses a low voltage input to turn itself on and off while at the same time it provides a higher voltage or high current circuit with power. It's basically a safety feature. It allows you to use higher voltage to power the lights without passing that power through 60+ year old switches that may or may not be capable of handling a high voltage input.

In the case of our older cars we use relays to provide power directly from a high amp source such as the starter power circuit or alternator output and run that power directly (through the relay) to the headlights. This gives us brighter headlights that won't dim when the engine is at idle. The light switch is simply used to switch the relay on and off for the low beams and the bright light switch on the floor (which receives its voltage from the light switch) is used to switch the relay on and off for the high beams. At least that's the way I use them.

Using a relay allows you to run higher amperage wire as well. The headlights on our old Mopars usually use a 15 amp circuit and 16 gauge wire. The power for this circuit comes through the dreaded bulkhead connector through the headlight switch then through the dimmer switch, back through the dreaded bulkhead connector and eventually to the headlights. Each connector in the circuit robs it of a little voltage and by the time the power gets to the bulbs it is somewhat less than what it started out to be. This is especially true with 60 year old connections and wires.

When you use a relay in the circuit you can take that lower power provided by the stock headlight circuit and use it to switch on a relay which gets its power directly from a high amp source through a higher rated wire and higher amp breaker. The result is more reliable and brighter lights. It's pretty much that simple.

On my '64 Polara I run dual relays that draw their power directly from an insulated terminal block on the firewall. This terminal block gets its power from the positive connector on the starter and also provides power to the fuse panel thus eliminating the dreaded bulkhead connector. The two wires heading off at 3 o'clock from the terminal block go to the two relays.

IMG_5961a.jpg


From this terminal block I run 10 gauge wires (overkill) through twin remote 30 amp circuit breakers (also overkill) to the relays and from there on to the lights. I could have used 12 gauge wires and 20 amp breakers and it would work just as well. (The circuit breakers are those double barreled looking things just below the yellow wires and gray clamp in this pic below.) They're switched using power from the stock headlight switch and dimmer switch. I've used this system on several cars and it works flawlessly.

IMG_5942a.jpg
 
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For those that don't know, I had a pretty serious medical condition almost take me out on 12/27. 2020 sucked for a lot of reasons and it tried to get me at the end. Heres to 2021 being a better year!

I will be producing relay kits when I can which I hope is a week or two when I get more strength/stamina.

Thanks for the inquiries and I look forward to building kits again.
 
For those that don't know, I had a pretty serious medical condition almost take me out on 12/27. 2020 sucked for a lot of reasons and it tried to get me at the end. Heres to 2021 being a better year!

I will be producing relay kits when I can which I hope is a week or two when I get more strength/stamina.

Thanks for the inquiries and I look forward to building kits again.
Sorry to hear but good you are getting back on your feet.
 
Funny thing, I could probably do them now, but medical procedures through wrist/forearm has messed up my strength in right hand. Can't grip anything to use crimpers. If not for that I'm sure I could do one a day and not get gassed.
 
Funny thing, I could probably do them now, but medical procedures through wrist/forearm has messed up my strength in right hand. Can't grip anything to use crimpers. If not for that I'm sure I could do one a day and not get gassed.
Here's to a speedy recovery!!!!
 
I don't mean to insult anyone's intelligence here but the thought occurred to me that some may not understand what a relay is and why it's a good idea to run relays for headlights on our older cars.

If you've ever seen a 50's or early 60's car at night you may have noticed their headlights seem to dim a little when the engine is idling, for instance at a red light. But when the light turns green they brighten up again when once the engine rpm is increases. Running relays solves this problem.

Now I'm not an electrical engineer, but here is my understanding of what a relay is. Just think of a relay as a high voltage switch. That's all it really is. It's an electrically operated switch that uses a low voltage input to turn itself on and off while at the same time it provides a higher voltage or high current circuit with power. It's basically a safety feature. It allows you to use higher voltage to power the lights without passing that power through 60+ year old switches that may or may not be capable of handling a high voltage input.

In the case of our older cars we use relays to provide power directly from a high amp source such as the starter power circuit or alternator output and run that power directly (through the relay) to the headlights. This gives us brighter headlights that won't dim when the engine is at idle. The light switch is simply used to switch the relay on and off for the low beams and the bright light switch on the floor (which receives its voltage from the light switch) is used to switch the relay on and off for the high beams. At least that's the way I use them.

Using a relay allows you to run higher amperage wire as well. The headlights on our old Mopars usually use a 15 amp circuit and 16 gauge wire. The power for this circuit comes through the dreaded bulkhead connector through the headlight switch then through the dimmer switch, back through the dreaded bulkhead connector and eventually to the headlights. Each connector in the circuit robs it of a little voltage and by the time the power gets to the bulbs it is somewhat less than what it started out to be. This is especially true with 60 year old connections and wires.

When you use a relay in the circuit you can take that lower power provided by the stock headlight circuit and use it to switch on a relay which gets its power directly from a high amp source through a higher rated wire and higher amp breaker. The result is more reliable and brighter lights. It's pretty much that simple.

On my '64 Polara I run dual relays that draw their power directly from an insulated terminal block on the firewall. This terminal block gets its power from the positive connector on the starter and also provides power to the fuse panel thus eliminating the dreaded bulkhead connector. The two wires heading off at 3 o'clock from the terminal block go to the two relays.

View attachment 1052055

From this terminal block I run 10 gauge wires (overkill) through twin remote 30 amp circuit breakers (also overkill) to the relays and from there on to the lights. I could have used 12 gauge wires and 20 amp breakers and it would work just as well. (The circuit breakers are those double barreled looking things just below the yellow wires and gray clamp in this pic below.) They're switched using power from the stock headlight switch and dimmer switch. I've used this system on several cars and it works flawlessly.

View attachment 1052056
Amperage not voltage. "Now I'm not an electrical engineer, but here is my understanding of what a relay is. Just think of a relay as a high voltage switch. That's all it really is. It's an electrically operated switch that uses a low voltage input to turn itself on and off while at the same time it provides a higher voltage or high current circuit with power. It's basically a safety feature. It allows you to use higher voltage to power the lights without passing that power through 60+ year old switches that may or may not be capable of handling a high voltage input." Amperage not voltage.
 
You need a source of ample 12v power (starter solenoid, etc.) and the wires from the dimmer switch have to connect to the relay input power connections. OK?
Mike

Go right to the battery for 12v. My relays are mounted on the radiator support by the battery. It's a short run from battery to relay.
 
For those that don't know, I had a pretty serious medical condition almost take me out on 12/27. 2020 sucked for a lot of reasons and it tried to get me at the end. Heres to 2021 being a better year!

I will be producing relay kits when I can which I hope is a week or two when I get more strength/stamina.

Thanks for the inquiries and I look forward to building kits again.

Rob, sending prayers out for a fast recovery. Take care.
 
Thanks Mike

I did not use a kit as I have some relays around that I saved from my years as a tech at the Dodge dealer so I used my own relays and wiring. But its actually very easy to wire relays into the headlite system. Basically you can do what I did which is cut the wire harness open just before it gets to the headlites as I opened my harness right on the drivers fenderwell near the rad just before it goes through the core support. It helps to have the cars wiring schematic so you know what color wires go to the high and low beams. You can cut the wires right where you open the harness as I cut the wire that feeds both low beams and the wire that feeds both high beams. Then you take the low beam feed wire which is coming from the dimmer switch and wire it to one of the relay coils and then ground the other side of that relay coil. That uses two relay terminals and then you run 12 volts which you need to fuse to one side to the relay contacts and then the other side of the relay contacts goes to the low beam wire you cut going to the low beams. Thats the other two terminals on the relay. Now on the relays pin 86 should be the relay coil feed which is the wire from the dimmer switch in the harness you cut. Pin 85 will be a ground on both relays. Terminal 30 on the relay you connect to battery volts which will be a fused 12 volt source like from the 12 volt hot all the time stud on the starter relay. And last terminal 87 on the relay goes out to the headlites which you connect to the headlite side of the wire you cut in the wire harness so it will send the 12 volts from the 12 volt source you use at the starter relay or right off the battery that you fuse and that 12 volts will go through the relay contacts when you turn on the headlites right out to the headlites low or high beam depending on which you have on. So all you are doing is taking the feed to the headlites off of the headlite switch and now the headlite switch will just turn on the relay which is very litttle amps. And then the relay will send 12 volts right to the lites eliminating all the wiring through the firewall and bulkhead connections and also eliminating the load through the headlite switch. Its a piece of cake. And if you do buy a kit it just makes the job even easier. Ron
 
Just read about your health issues. Glad thing's are getting better for you.
For others wanting to do this. I recommend doing it. I ordered and installed crackedback's kit tonight, worked great. Hard to tell in pictures but they are much brighter. Best part is my headlights no longer flicker with the high beams on after awhile and my switch is no longer hot to the touch.

20210128_180029.jpg 20210128_191611.jpg 20210128_191817.jpg
 
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