Swapping out cobra headlamps for headlights

[Curmudgeon]

I'm removing the old cobra front headlamps for full sized headlights (55 w each). Who ever set up the old 35 w lamps was an %^&**(&. He ran it through the lighting circuit for the gauges. I'm amazed that it worked and that I never had trouble with it. Nun of the connections were soldered.
The question I have is about relays. May years ago I did the headlight mod bumping my headlight wattage up to 100W. It works perfectly with a dual relay which I can't seem to find anymore. Now with the new lights I'm running a single 12 gauge wire to the battery. I'm guessing I'll have to use a relay. I have 2 questions. Do I need a relay? If I do will I need 2 relays, one for each light or will one do?  What make and rating and where can I get them? I was not going to use the brights but if I do I'll hook an independent switch to the handlebars for them.
Any comments will be appreciated. 

[Michvalk]

I wouldn't add any lights without a relay. You can use the old circuit to trip the relay, or there is an accessory line under the right sidecover. I am not an expert at electrics, but at least that is some basic knowledge for you

[t-man403]

This is the relay you need.

http://www.autozone.com/autozone/accessories/Santech-5-pin-12-Volts-dual-output-relay-with-bracket/_/N-2659?itemIdentifier=946045&_requestid=904998

[Curmudgeon]

Here are the schematics, and pic of of the dual relay that I have on the front headlight. Its the basic setup I'm looking for.


and

[Gryphon Rider]

I have two H4 headlights as auxiliary lights on my Valkyrie. I run them with fused and switched power from the battery to two relays. One relay feeds the high beams and the other the low beams of the aux lights. The relays are controlled by the factory high and low beam headlight wires respectively. The relays and wiring barely cram into the headlight shell. I usually have the lights on whenever the headlight is on, but can switch them using the switch in the dedicated power wire from the fuse. What I would do differently next time is look for a physically smaller relay that has a minimum 10A (higher is better) rating on both the NO and the NC contacts and only use the factory low beam wire for switching the relay.

[salty1]

Take a look at Chet's circuits shown below. Go to the fourth schematic. I used that approach and installed a fuse block to protect the bike's circuits from all the other wired add-ons.

http://www.rattlebars.com/valkfaq/circuits.html

[9Ball]

Based on your combined bulb wattage (55W x 2) and your system voltage (12V), you will be drawing 9.2 Amps (rounded up from 9.166666) through a single relay.  Use formula W = A x V.  Solve for A, therefore A = W/V

I would recommend at least a 30A relay, but it wouldn't hurt if you can only find a 40A relay.  Check the truck fog light aisle in your favorite auto parts store....they usually have them stocked there.

Yes, you definitely need a relay and only one is needed to provide power to both auxiliary lights.

[Curmudgeon]

Thanks for the help. I'll let you know how it works out. With pictures of course.

[Attic Rat]

Pilot makes a wiring kit with relay and switch. Pep boys carries it and I think auto zone under 30.00 I have used this kit several times and have had it on my number 1 since 98 no problems. Also  GE makes a air craft landing light that really works well with this kit O'Reilly carries it
http://www.amazon.com/Pilot-PLHARN3-Pre-assembled-Harness-Switch/dp/B001VGO800

http://www.ebay.com/itm/Pilot-12-Volts-Pre-Wired-Harness-Kit-w-Micro-Switch-pl-harn3-/111127326685