Headlight Voltage Drops

Things may be different for the guys who live in the sunshine but here in the UK we have rain sometimes so green wires are an issue.
Also aging and corrosion of the terminals of the fuse box create significant drops; so one solution to beefing up the feeds is the installation of modular blade fuse holders with the spade connectors covered in petroleum jelly to slow down the corrosion.
I did this to my recent purchase to minimise the chance of dodgy connections when I was recommissioning the electrics.
As it happens they all worked after this treatment and I only had to replace two bulbs in the tacho
Using modular single fuse clips allow you to put two double fuse holders in the available space.
Benefits include lower losses, the wider availability and lower cost of replacement fuses.
Generally carefully packing the exposed external parts of multi connectors with jelly slows down degradation of exposed metal, for single wire joins just packing the insulation sleeves is effective and looks tidy.
Packing should be done carefully and with the minimum of material as petroleum jelly is conductive so should be confined within each separated compartment of the connector rather than applied as a handful on the "more is better" principle.
My Ford Cortina has been protected from new in this way and still has functioning electrics, including bright lights, on the original wiring, I updated the fuse box to blade fuses ten years ago.
Oh yes,this does not work on HT leads at the spark plug end as the jelly runs and coats the ceramic with conductive liquid. I only did that once.
Everybody has the right to be stupid now and again and there is no amount of smart that will prevent stupid in my experience.
 
Attached is one idea I have to improve voltage to the headlight. I may even do this if the LED works out (find out tomorrow) because it removes the heavy load from the key switch and isolates the headlight from the ignition so the ignition voltage won't get pulled down by the headlight. The relays I bought are SPDT rated at 30 amps and are small enough to put one right behind the fuse block under the seat.

BTW, have been working through the connectors one at a time and continue to incrementally reduce the voltage drop but it will never be close to zero like it should be. Would really like to know how much was lost when it was new, I bet it was more that I would have liked.
 

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Attached is one idea I have to improve voltage to the headlight. I may even do this if the LED works out (find out tomorrow) because it removes the heavy load from the key switch and isolates the headlight from the ignition so the ignition voltage won't get pulled down by the headlight. The relays I bought are SPDT rated at 30 amps and are small enough to put one right behind the fuse block under the seat.

BTW, have been working through the connectors one at a time and continue to incrementally reduce the voltage drop but it will never be close to zero like it should be. Would really like to know how much was lost when it was new, I bet it was more that I would have liked.
I am not sure what that relay would accomplish. I still strongly believe in the shortest, simplest wiring from battery to light bulb. And a very good ground.
So the power flow like this, one relay for hi beam, one for low beam:
Battery- fuse (modern flat type, waterproof holder)- relay- light bulb connector. I would use 1.5 sq.mm cable as a minimum. 2.5 sq.mm if it does not cause packaging issues.
Losing that "safety relay" is hardly a big deal. Newer bikes don't have it.
 
Probably should have a means to turn the headlight off when parked;)
 
Probably should have a means to turn the headlight off when parked;)
Turning the key would turn off power, in his schematics.
As for my suggested setup, I would use the original hi/ lo to the bulb for controlling the relays. So would function like stock, except for that unneccessary safety gizmo.
 
Headlight operation remains identical to stock with the safety relay or the handlebar switch turning it on and it will not come on with the key switch turned off. BTW, that resistor connected to the safety relay reduces the brightness of the headlight, extends headlight life and reduces power consumption during the daytime much like a lot of cars do. So in the daytime I run the high beam at reduced power.

I don't want to eliminate the reserve lighting unit, it is a good idea because in the daytime you will never know if the headlight quits. Yes you can bypass all of the extra stuff and get the lowest drop possible but that is not what I want. And, if I do not like the LED I plan on adding a new ground connection from the headlight to the frame under the tank where I am losing almost 1/2 volt.
 
Perhaps I see it wrong
But the safety relay is it not closed ..conducting power ..at key on
If so the headlamp gets power no matter the position of the top left Handlebar Switch.
If so a 3 way switch at the other Handlebar Switch can be an option one with an OFF position also.

And if the safety relay should open and the top left is closed the safety relay is jumped and not operating
Its cutoff purpose
Maybe I am wrong here ?

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The coil of the safety relay is powered by the alternator as per stock. When the engine starts the contacts close. Stock the safety relay contacts are in parallel with the handlebar switch, I added the resistor to dim the light in daytime.

The only change in the headlight circuit compared to stock is the source of the power. In the stock setup the left sides of the ignition, signal and headlight fuses are all connected together and power comes from the key switch. In this drawing the ignition and signal fuse connections are unchanged, but the power for the headlight fuse now comes directly from a new connection to the battery and the output side of the fuse goes through the relay to power the otherwise stock headlight circuit. The relay coil is energized by power coming from the key switch.

This eliminates the high current through the key switch and the wiring to it and consequently the voltage drop.
 
Got it done today, and everything works. Was able to tuck the relay under the battery strap. I'm still not quite satisfied with the wire routing but its OK for now.

I also received the LED bulb from Amazon. Too cold to go for a ride but seems to be quite a bit brighter than the halogen. One down side is I had to bypass the reserve lighting unit, I was hoping the LED would draw enough current to make it work properly but such is not the case.

Looking forward to trying it out after dark but probably won't be able to do that for quite some time. :-(
 

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Looking forward to trying it out after dark but probably won't be able to do that for quite some time. :-(
I hate to rub it in, but I’ve been out and about on mine today.

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Not really. I do like to rub it in. :poke:

This bike is all LED, except the headlight.
 
Well that h4 led crapped out already. Looks like a mechanical failure, it has 2 leds for low and 2 for high beam. One of each works intermittently when the terminals are moved. Put a halogen back in.
 
Well that h4 led crapped out already. Looks like a mechanical failure, it has 2 leds for low and 2 for high beam. One of each works intermittently when the terminals are moved. Put a halogen back in.
Over 4,000 miles on the LED headlight in Madness.
 
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