Isolating All the lighting systems

[sjkrebs]

Hi all,
I'm starting to build a new wiring harness for my chopper.
I'm running with only a capacitor in place of the battery, a custom permanent magnet alternator and therefore kick-start only. To aid in being able to kick the bike over with the most power available for spark I'd like to isolate all the lighting systems and be able to turn them on after the engine is running smoothly.

I understand wiring schematics and I am confident on how to wire the different options I'm looking it. What I need help with is what is the better option.

It seems that the "modern" way to isolate this is to use a relay controlled by a switch.

Easy/Old School way is to just use a switch.

Which is the better choice? Why?

[grinder]

I am using a couple of relays for things on my bike. I guess the downside would be if the coil on the relay fails so does what the relay is powering. Very low current draw on the relay's coil though, I'm hoping they last a long time but will carry a spare.

[xsleo]

Pamcopete has used a relay in his ignition circuit to power the ignition straight from the battery. The kill switch just turns the relay off and on. He has used it for years.
I have done this on my bike. The kill switch can be a source of ignition problems.
Having the headlight on it's own switch is a good idea. Thats how the older bikes were set up. The tail light lit with the key on. This was a safety thing.
I have my 75 wiring set up so with the light switch off none of the lights are lit. this leaves all the power for starting the bike. I also ride around with out the lights because I forget to turn them on.
I'm thinking of wiring in a safety relay from a later bike and have it turn on the lights when the bikes running. I will run it through a resister as well, this will light the headlight at about 3/4 power. This will save a bit of amps. When I turn the headlight switch on it will bypass the resister and come on full bright.
I have also converted all but the headlight and gauge lights to LED's. This save a bunch of amps. Charges the battery much faster.

[ShakerNorm]

The usual reason for using a switch and relay rather than just a switch to control a large power draw (such as the entire lighting system on your bike) is that the power draw will spark every time the switch is turned either on or off. Of course this burns out the (usually small) contacts on the switch, which will eventually fail. Relays are made to take the larger current draw and handle the spark - so over the long term, it makes them more reliable, and your switch (which usually has pretty small contacts) isn't as apt to fail, either.

[kopcicle]

I will run it through a resister as well, this will light the headlight at about 3/4 power. This will save a bit of amps.

wana try that again ?

~kop

[tonyc2me]

If you keep your switch,good quality,close and the proper gage wire you will not need a relay. Of course having one will make things better. I am not using one on my self-made harness. I separated all of my lighting, charging, and ignition circuits. Each one has their own fuse. Good Luck Tony C.

[pamcopete]

Well, one of the problems with using a switch for the headlight is that you will probably forget to turn it on and that can lead to a ticket, or an accident, so you can use a relay operated by the neutral switch to turn the headlight off when in neutral for starting, but the relay will turn the headlight on when you put the bike in gear in case you forget to turn on the switch.

[sjkrebs]

Thanks, Pamcopete. But can you elaborate for me? I know how to do that using the neutral switch if the setup is battery powered, but that wouldn't work with a batteryless setup. So can you explain to me how to do it? Perhaps my knowledge of the neutral switch is confused so you might want to include that. Thanks.
(Also to be specific, I'm using the banshee permanent mag setup on this bike, the reg/rec has 4 blades, 3 for the white wires from the stator and one for the red wire which is wired to a capacitor)