Adding Driving Lights - Relay or Not?
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Road Warrior
Joined: Feb 2008
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From: Sarasota, Florida
Adding Driving Lights - Relay or Not?
I am adding some "driving lights" to my Ultra. I already have the lights and harness but was wondering if I should wire in a relay and if so which one and where should I get it. I think I need one and I should be able to get one at Pep Boys or Autozone.
Thanks in advance!
Thanks in advance!
Extreme HDF Member
Joined: Apr 2006
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From: Roswell, GA
Hope you get a more educated response, but I agree you should use a relay--the relay allows use of a low amp rated on/off switch to control the relay. It's the way the HD fog lamps I used to have and the Motolights I recently installed are wired.
Don't know the amp draw of the driving lights you are using, but a 10 amp single pole/single throw relay should be adequate with an inline fuse of comparable amperage if you are wiring it to the battery.
Don't know the amp draw of the driving lights you are using, but a 10 amp single pole/single throw relay should be adequate with an inline fuse of comparable amperage if you are wiring it to the battery.
Former Sponsor
Joined: Apr 2007
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From: Davie, FL
Driving lights?
What exactly are you talking about and what is the application specifications? Much more information is needed. Are you talking about the cheap auto type, 250 watt/each landing lights, car fog lights, or one amp LED bulbs? I have been working in this area for a while there is much to be considered. You have provided no useful information for us to correctly give advice. Please think about the power draw than think about the lens (lamp) and where you want the light. Where you put the light is also important but as far as your original question to be answered, what is your power draw?
Last edited by FastHarley; Sep 9, 2008 at 10:51 AM.
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Road Warrior
Joined: Feb 2008
Posts: 1,484
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From: Sarasota, Florida
The lights are 2 1/2" diameter chrome bullet stlye with 50 watt halogen bulbs, so 100 watts total. I will mount them on the crash bars near the bottom, (low as possible) using the Kuryakyn Magnum clamps. This should give me the distinctive triangle light attention from the front. I have thought about the current draw and these lights would not be used all the time. I already have changed all other bulbs to LED's, so I'm saving draw there.
Howard, I will get your H.I.D. in the future, when the moolah is flowing better. That will save me draw also.
Howard, I will get your H.I.D. in the future, when the moolah is flowing better. That will save me draw also.
Former Sponsor
Joined: Apr 2007
Posts: 5,360
Likes: 453
From: Davie, FL
Yes you should
The lights are 2 1/2" diameter chrome bullet stlye with 50 watt halogen bulbs, so 100 watts total. I will mount them on the crash bars near the bottom, (low as possible) using the Kuryakyn Magnum clamps. This should give me the distinctive triangle light attention from the front. I have thought about the current draw and these lights would not be used all the time. I already have changed all other bulbs to LED's, so I'm saving draw there.
Howard, I will get your H.I.D. in the future, when the moolah is flowing better. That will save me draw also.
Howard, I will get your H.I.D. in the future, when the moolah is flowing better. That will save me draw also.
Former Sponsor
Joined: Apr 2007
Posts: 5,360
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From: Davie, FL
sorry
Continue.....Read the following pages and get the information that is revelent to your project. Go here How To: HID Open….Than read this What Others Will Not Tell You about modifying your Motorcycle Lighting LINK
To view a relay. If your relay is only 4 prong than the 87a pin is missing which is a straight through always on one. Now run your red fused wire to pin 30. Run your new blue wire from pin 87 to each one of the running lights. Remember that when the lights are in series (light 1 hot through filament to light 2 through filament to ground) doubles the resistance whereas blue wire to each bulb (think Y) than both bulbs to ground (each) is just the resistance of the filament of one bulb and wire. Less resistance = less voltage drop = brighter the bulbs…
2nd circuit is to excite the relay. Your key switch on position of your choosing than you can put on a small low power interrupter switch (HERE) Perko fig. 0701 - push button switch that is found at almost on the bottom of the page in series to pin 85. Pin 86 goes to ground. 85/86 is low power whereas 30/87a/87 are high power circuits. You can also put a pair of relays to control how to turn on the driving lights ie: Lo/On ~ Hi/Off or visa versa. If there is any interest, write. I hope this helps..H
To view a relay. If your relay is only 4 prong than the 87a pin is missing which is a straight through always on one. Now run your red fused wire to pin 30. Run your new blue wire from pin 87 to each one of the running lights. Remember that when the lights are in series (light 1 hot through filament to light 2 through filament to ground) doubles the resistance whereas blue wire to each bulb (think Y) than both bulbs to ground (each) is just the resistance of the filament of one bulb and wire. Less resistance = less voltage drop = brighter the bulbs…
2nd circuit is to excite the relay. Your key switch on position of your choosing than you can put on a small low power interrupter switch (HERE) Perko fig. 0701 - push button switch that is found at almost on the bottom of the page in series to pin 85. Pin 86 goes to ground. 85/86 is low power whereas 30/87a/87 are high power circuits. You can also put a pair of relays to control how to turn on the driving lights ie: Lo/On ~ Hi/Off or visa versa. If there is any interest, write. I hope this helps..H
Last edited by FastHarley; Sep 9, 2008 at 01:59 PM.
Former Sponsor
Joined: Apr 2007
Posts: 5,360
Likes: 453
From: Davie, FL
PS
I am not too thrilled with that triangle thing as it confuses drivers. Put it straight across as people will relate and not take time to think. My opinion only and what I thought when seeing fork mount or crash bar mount. It is your bike so do what you like.
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Road Master
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Simple answer - yes, install a relay (exactly what sort of switch would you use to switch 100Watts of power). Couple dollars at Auto Zone. The more pressing question is where to tie into +12V switched power - look into the B+ connection under the seat - Harley sells cable adapters for it.
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I buy heavy duty 30 and 40 amp relays. Even when using them in a lower amprage ckt. The contacts are what the heavy duty rating is for not the coil. The coil connects to the low amp switch that feeds the relay or is feed from the stock bike wiring such as horn power lead or stock pwr to what used to go to "Passing Lamps". This isolates your new or re-powered lighting or device of choice that you want steady power and volts direct from battery, with fuse inline of course.
Yes most "Highly" recommend using relays in any additions, or mod's to existing wiring to shead loads.
And if you keep a relay set of contacts in your bag. You can jumper a defective relay in a heart beat and keep rolling until you get to a repair site. My jumper is a lugged out fuse holder with an assortment of fuses to plug into it. So depending upon if or when I get a relay that wants to take a dump, I just plug in the fuse holder. Sure its hot (not temp, but turned on with power) until I pull the fuse but thats saving me time if I can't get another relay right away.
Yes most "Highly" recommend using relays in any additions, or mod's to existing wiring to shead loads.
And if you keep a relay set of contacts in your bag. You can jumper a defective relay in a heart beat and keep rolling until you get to a repair site. My jumper is a lugged out fuse holder with an assortment of fuses to plug into it. So depending upon if or when I get a relay that wants to take a dump, I just plug in the fuse holder. Sure its hot (not temp, but turned on with power) until I pull the fuse but thats saving me time if I can't get another relay right away.