I'm not sure what gauge the OEM wire harness is so I'm not much help. Hopefully one of the other members that has more electrical sense than me can chime in.

 

Consider this at 35 watts on a 12 volt system you are drawing 2.9 amps per bulb. at 100 watts on the same 12 volt system you are drawing 8.3 amps per bulb. So you would be almost tripling the current draw through the wires.

 

Wire size (Gauge) is determined by the Amperes the wire will be asked to carry and the distance/length of the wire. To determine the expected Amperes use the formula: Watts (P) = Voltage (E) X Amperes (I). Simplified this is P=E*I, or in terms of the Amperes it is I = P/E. Do NOT use 12 Volts as the voltage. The normal charging system voltage range is 12 to 16 volts. Since Amperes increase with increasing voltage, you must use 16 as the voltage in your calculations. Use this formula along with the attached chart to determine the proper wire gauge/size. I would consider lighting to be a "critical" circuit for the purposes of this chart.
:nerd:
For example: To run two 100 Watt lights (200 Watts total) on a circuit that can see 16 volts; the amperage I would use for my calculations would be: I = 200/16 or I = 12.5 Amperes. Looking at this chart, to be on the safe side I'd use the 15 Amperes column. If the total wire length is 0-6 feet use a 14 Gauge wire, 6 to 10 feet go up to a 12 gauge wire, etc. While under-sizing the wire (higher gauge number) by a little bit, emphasis on "little," is not likely cause a safety problem, it will cause a voltage drop in the circuit that will lower the performance (light output) of the lamp.

 

Since Amperes increase with increasing voltage, you must use 16 as the voltage in your calculations.
For example: To run two 100 Watt lights (200 Watts total) on a circuit that can see 16 volts; the amperage I would use for my calculations would be: I = 200/16 or I = 12.5 Amperes.

Minor correction. Amperes DECREASE with increasing voltage. Using a lower voltage will be more appropriate. 200w/12v=16.7 amps. Your wires and connectors must be able to carry that load. Good luck with your mod, and hopefully Bluehighways can recommend the proper size wire. :nerd:too

 

Resistance is futile.

 

Resistance is constant.:wink2:

 

I can resist everything except temptation.

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The wiring can handle 55W bulbs, but the switch on it’s own will not and the circuit will require a relay to carry this load. I would not use 100W bulbs that close to the roadway, half of the light will be wasted on the roadway directly in front of the bike and not projected very far down the road.

Resistance is constant and the power and current will vary with the voltage applied. Goodluck, don’t burn it down...

 

I want to thank everyone for the help. Ron Robertson, Bluehighways.. thanks a lot for the chart and the writeup. I saved the chart and I'll be using it in the future too.

Nremtp - Techdude 2000 - Budoka - Chopin - thanks guys!

Looks like I'm not going to burn things up now! I'm going to measure the wire's gauge and go from there. My feelings without looking at the wires but at the chart I'll go no higher than the 55w.

 

And the increased heat generated by the 100w bulbs. Remember, you are mounting these is a plastic cowl. About 95% of the energy is in the form of heat.