Auto Electrician advice needed

[panheadpete]

Originally Posted by Limey_Dave

I thought that using a change-over relay switched by the dip switch meant that only the (low) switching current went through the original loom and that would be less than with the original settup.

Using two separate relays, the current can all bypass the entire loom but with just one switchover relay it has to pass through the ignition switch, otherwise one or the other light would be permanently on. The one-relay system takes the load off the dipswitch and headlight wiring in the loom, which is good. I should add that I mean the heavy current as opposed the tiny current needed to activate the relay(s).
Cheers,
Pete

[Ukkid76]

Originally Posted by panheadpete

Using two separate relays, the current can all bypass the entire loom but with just one switchover relay it has to pass through the ignition switch, otherwise one or the other light would be permanently on. The one-relay system takes the load off the dipswitch and headlight wiring in the loom, which is good. I should add that I mean the heavy current as opposed the tiny current needed to activate the relay(s).
Cheers,
Pete

No Panheadpeat the relay operates the dip beam continuously without having to use any switching at all, so the dip switch is in affect dead,

When the rider flips the switch from dip beam to main beam it operates the relay which then switches the main beam on and the dip beam off,

I have two relays fitted to my bike only so I could use a 100 watt bulb not to put two bulbs on at once, I would have used just one relay had I known then what I know now!!

I don't run a 100 watt bulb now because the new headlamp I now have is plastic and won't take the heat from a 100 watt bulb, but I must admit the new plastic head lamp unit is really good and bright, and made even better when it is angled correctly.

[panheadpete]

OK Kid, go for yer guns!
The point I was trying to make, probably not very well, is that yes, the single relay operates that way but where does it get its main (not switching) power from?
Can't be straight from the battery 'cos, as I said, you would then have one of its outputs permanently live, regardless of the dipswitch - it has to be supplied from the ignition switch.
Another advantage of using two separate relays, even if for one filament each, is that you have two totally independant, fused, lighting supplies so that even if you get a short or break in one, you've still got the other (provided the fault isn't in the main loom).
That sound you just heard was me ducking behind the watering trough to reload.
Cheers,
Pete

[banquo]

Yes, that's entirely right.

To avoid taking the power for both lamps through the ignition switch, you need a feed wire from the battery, fused accordingly, to a relay that is off when ignition is off, and on only when ignition is switched on. The coil in the 1st relay is energised by the ignition 'on' output. The power output from this 1st relay is the feed wire for the second, changeover relay. Another alternative is to forget relay No. 1, and fit a waterproof switch, that way you can have ignition on and lights off, something that you haven't been able to do an a Harley for many years, but which can come in very useful when you're starting your bike with a low battery.

Another (and better?) way of doing it is to use the existing headlamp wiring to feed one side of the twin headlamp circuit. You already have all the wires and switchgear for that, and you won't overload anything. Then you operate only the second lamp from the separate feedwire and relay. This halves the size of cable and relay required, and is the preferred way for adding equipment to an existing circuit.

It's worth checking the wiring diagram to see if there are already spare, fused feedwires in place (e.g. for passing lamps) to avoid the mess of chaining up additional feedwires directly to the battery positive.

Some looms do have pre-wired sections for add-ons I think, but I don't have the book here right now.

[panheadpete]

Good ideas banquo and well put; wish I could explain things like that.
Just would like to add that any spare, fused feedwires should be permanently live or else you're back to going through the ignition switch to supply them.
Oh, and you might find that using the original loom for one light and a relay for the other gives you one light that's brighter; a sure sign that there's voltage drop across the ignition and dipswitches - a big advantage of relays.
Cheers,
Pete

[Ukkid76]

Originally Posted by panheadpete

OK Kid, go for yer guns!
That sound you just heard was me ducking behind the watering trough to reload.
Cheers,
Pete

No problem pete you don'thave to reload your shooter!!

This thread is getting soooooooo booring now I think I'm gonna go and shoot my self



I enjoyed crossing paths with you and have learnt and a thing or two................. From Rodger that is!!!!!

[Roger]

Originally Posted by softail898

By the way Roger, your Setup will not work...you have an Earth on both sides of the Relay Coil, the Relay won't operate!

You're quite right, one pole of the dipswitch should of course go to live terminal not negative .