Originally Posted by davek181
I prefer simplicity myself, the less there is, the less there is to go wrong. i also like the idea of splitting the lights, one AC, one DC for the fact that you are drawing on two different sources available without overloading either. The DC side is relatively unused except for signals, brake and tail and instrument lights.
I would leave one headlight as stock, through the switch and wiring you already have, the AC light would function as normal. The DC light I would run through a relay from the fused and switched battery source available. I would use a 5 prong relay with the 87a and 87 connectors on them. The relay connects 87a while at rest and 87 when activated. Connect the low beam to the 87 and when you turn on the key low beam will come on automatically if you have it wired from 30 to 87a. (alternately you could mount a separate switch to be able to turn off that light independently)
For high beam I would trigger the relay from the existing high beam switch wire through terminals 86 and 85. Both lights will come on automatically, though the AC light will have to wait for the engine, and switch to high beam with the one stock switch.
If you were to change your signals and tail and instrument lights to LED as I have it would also free up more amperage for other options, such as heated grips, while not overloading anything.
Sounds good in theory in my muddled brain, the only grey area I can think of is whether the relay will trip on an AC source, haven't experimented with that yet. I suppose you could add a diode in the switching circuit to straighten out the waveform if needed.
Just my $.02
Thanks for the advice and details. I'll mock up a 'wiring diagram' and post it here for feedback. I think there are AC relays as well as DC relays, but I think the DC relays are the ones that you can easily get at an auto parts store. I also think that I could get a small reg/rec to go inline from there to convert it DC, but that's just conjecture at this point.
The main thing I was worried about was the blue wire from the switch to the highbeams, as I'm not sure if it supplies current or acts as a ground, though I don't think it does...
I think I'm going to do the AC/DC light route though, as it'll allow the bike to return to stock like I want, and might allow for a brighter light on the DC side from the lack of draw from the DC side of the system (basically only the taillight and signals).