LED Headlight Bulb

[graeme]

I had the enjoyable experience of riding home the other night in the dark without lights. (and in the rain)
I went out and came home after dark with the lights on for about 15kms then the engine cut out.
Turn the lights off and forward progress was resumed, turn the lights on and the noise stopped again.
I know the Scrambler alternator (fitted to the RT) is very marginal running a headlight bulb, tail light, electronic ignition, electronic dash and idiot lights. Plus the brake light now and again.

This is an RT running 12 volt and a small battery.

I first thought about chasing up a 40watt H4 bulb, then a friend suggested trying a LED which draws about 5 watts.

Has anyone used one of these LED H4 bulbs?

Graeme

[JimF]

Hi Graeme,

Do you have a link you can post to the LED headlight you are considering?

In some areas LEDs are sanctioned for daytime running lights only.

Some LEDs may not have high and low beam emulation, so if you need that to pass an MOT or inspection the LED may not get you passed.

A 5-watt LED product will only put out about the same amount of light as a 25 watt bulb, so you may need more than a 5 watt product.

LEDs are polarized and need current flow in one direction only (DC voltage) but I glean that you are running a DC bike.

LEDs don't emit the full additive color spectrum, so streets, signs, and other objects at night may take on a strange hue when lit by the LED light.

Jim

[graeme]

Hello Jim,

I don't have any specific brand or supplier in mind.
I see that they are advertised on eBay as suitable for fog lights and such, so I figured they may not pass regitsration or MOT.
I'm not looking for a headlight that will cook a chook at 30m, and I understand they aren't as bright as incandescent bulbs at a distance. But I'm looking more for a light that would allow other traffic to see me at night if I get caught out in the dark again.
Although a good LED H4 would be nice if there is such a thing.
One I saw did have high/low beam, and yes my existing light is dc battery fed.

Graeme

[DewCatTea-Bob]

" I went out and came home after dark with the lights on for about 15kms then the engine cut out.
Turn the lights off and forward progress was resumed, turn the lights on and the noise stopped again. "
I know the Scrambler alternator
is very marginal running a headlight bulb,
running 12 volt and a small battery. "

____ Such as this has already been gone-over at least a half-dozen times.
__ The stock w-c.alternator has no trouble at all powering a STOCK electrical-system's normal power-requirements (with power to spare) !
However insufficient power issues begin when the chosen headlight-bulb consumes over 50-watts and the engine's average-RPM is too low to keep the battery's power-storage balanced.
So in such case, (as you've experienced), the running headlight draws-down the system-voltage too low to maintain adequate ign.spark, until the lights are turned-off, (at which point the system-voltage level rises back up & then sufficiently powers the ignition).
__ I'd like to know what kind of RPMs you were averagely running, and how many watts your installed headlight is rated to consume. _ And also, how many Amp-Hours your installed 12v.battery is rated for.
Then maybe discussion of your particular employed charging-system might be in order.
__ Here follows a link to another thread telling of a likely cure for such an issue (as you've encountered)... viewtopic.php?f=3&t=106&p=4632&#p4632


" a friend suggested trying a LED which draws about 5 watts.
Has anyone used one of these LED H4 bulbs? "

____ The possible use of that type of light-bulb has also been touched-on before.
Unfortunately OUR search-engine either pulls-up too MANY hits, or none at all !
I'll keep looking.....

UPDATE... I found one (of at least two) other old/past-threads related to LED.light-bulbs, (although this one doesn't seem to be the best one for YOUR concern). _ Here's a link to it... viewtopic.php?f=3&t=228&p=1523#p1441


Hopeful-Cheers,
-Bob

[graeme]

Hello Bob,

You are correct regarding a standard Scrambler electrical system,,,,, I should have chased harder for a low wattage H4 headlight bulb when I wired the bike. (as you suggested earlier) But I didn't as I was too eager to ride it, then the light was forgotten until it caught me out.

It presently has a 55/60 headlight bulb, which was in the aftermarket head light.

Average about 4500 revs which should be ample engine speed to maintain a good charge, and it is. From memory it is giving 14 volts at just under 3000.
My problem with night riding is the amount of wattage drain is more than the system can replace.

The battery is only a small battery, a larger one could be fitted with some modification to the battery tray but a larger battery would only prolong the advent of dark silence. (with the present light bulb)

I'll read your posted link, thank you.

You did mention Phillips or Sylvania make a 40/40 watt headlight bulb?

Still interested in LED experiences though.

Regards
Graeme

[DewCatTea-Bob]

" It presently has a 55/60 headlight bulb, "

____ Your w-c.alternator should be able to cope with powering that strong of a light-bulb, so long as you keep the RPMs revved higher (than you've been).


" Average about 4500 revs which should be ample engine speed to maintain a good charge, and it is. From memory it is giving 14 volts at just under 3000. "

____ But of-course what REALLY counts is the resulting average-voltage from your average-RPMs, WHEN running your lights ! _ Which evidently is considerably lower than your battery's expected 12-volts.


" My problem with night riding is the amount of wattage drain is more than the system can replace. "

____ That's no-doubt true, of-course,, as the stock-alternator was not expected to power so much system-load wattage (as you've got), at expected average riding RPMs.
So you need to either reduce your system's wattage-load, or modify your charging-system, (if you don't wish to much increase your average-RPM riding-range).
__ You've probably done as most others have and simply wired-up your chosen rectifier/regulator-unit's input-wires directly to the two yellow-wires of your Duke's 6-pole alternator...
Doing that is sufficient for about a 35-watt lighting-system,, however for much greater -(by over about 50% more) power-draw, an impedance-mismatching becomes an issue for obtaining max.power-dissipation within the intended load-system.
So for greater load-systems (as you presently have), it's not very efficient to connect-up the two separate alt.windings in that rather common series-arrangement, (as most others often do),, as doing so then causes the alt.windings themselves to become as part of the overall load-system as well, (which means some portion of the alt.power-production is thus-then being wasted) !
So it should be understood that any significant change in the load-system, should in-turn be just-cause for matching alteration of the alt.winding-impedance, (so as to more-so efficiently spend alt.power-production).
__ You could possibly use your rect/reg.unit connected to ONE of the yellow-alt.wires & the red-alt.wire/common-lead, and use that circuit's resulted power-output (along with a suitable capacitor), to power your ignition-system (separately),, and employ a separate full-wave rectifier-unit (connected to the red-alt.wire & the OTHER yellow-alt.wire), for charging your battery & powering the lights. _ That way, when your battery becomes too low, the ignition will not suffer from loss of sufficient voltage, and you can then always be-on-your-way (even if the battery is completely dead).


" The battery is only a small battery, a larger one could be fitted with some modification to the battery tray but a larger battery would only prolong the advent of dark silence. (with the present light bulb) "

____ That's true but, (besides lasting longer),, a larger battery is also not as easy to get it's core-voltage dropped-down quite as far, when it has to help feed multiple loads, (thus the ignition may not become so easily cut-out).



" You did mention Phillips or Sylvania make a 40/40 watt headlight bulb? "

____ No, I don't know of such a bulb as that,, rather, it was a 65/45w H4-bulb (made specifically just for motorcycles), which I've preached about ! _ I believe it's brand-name & model-number was mentioned within the other (linked) thread.


Hopeful-Cheers,
-Bob

[graeme]

"____ Concerning a H4 type 12v.bulb, I only recall recommending Sylvania's 65/45w (bulb made specifically for motorcycles). _ THAT H4-bulb should work fine with such a stock-type Ducati charging-system. "

Sorry Bob, my memory is getting worse, you said 65/45w.

Graeme

[DewCatTea-Bob]

"____ Concerning a H4 type 12v.bulb, I only recall recommending Sylvania's 65/45w (bulb made specifically for motorcycles). _ THAT H4-bulb should work fine with such a stock-type Ducati charging-system. "

" Sorry Bob, my memory is getting worse, you said 65/45w. "

____ It seems I've forgotten as well, that we must've already gone-through this once before (somewhere-else, as my quoted-wording was not posted within THIS thread).
____ I've never had the opportunity to try-out such a modern 12v.bulb, but I do know that the stock charging-system can well handle a 45-watt headlight, so the only possible issue is extended riding with the 65w.high-beam left powered-up during lower RPMs. _ But with a charged battery, such a high-wattage high-beam should be fine for normal (relatively short-term) high-beam usage, especially at higher-RPM running.


Dukaddy-Cheers,
-Bob

[JimF]

If we are not looking to replace the headlight with a LED unit that satisfies MOT, SAE, DOT et al, then maybe we have a viable thread going.


I myself would like to run an LED as a daytime running light on the Mach 1 as opposed to throwing 25 watts of power away on the stock headlight. Without getting into a discussion about the charging system or its health, we might just look at LED driving lights as power-conserving alternative to running a headlight in daylight hours which is the law where I live.


While the LED would not meet the letter of the law it is unlikely that a policeman seeing a bright white light emanating from the front of my motorcycle in the daylight hours would stop me to investigate what the source of the light is or whether or not it conforms to legal standards.


More importantly, the drivers that I am approaching would hopefully notice a bright white light heralding my approach, and that may be better and safer than a 'legal" incandescent bulb that dims to a faint glow as I throttle down and pull the clutch in when approaching an intersection.


Is this the kind of application you were thinking of as well Graeme?


Jim

[graeme]

I don't try and ride at night, just if I get caught out.
We used to have the lights on thing in daylight too but not anymore, although I would think that bikes produced in the years when lights on was in may still have to have lights on as that's how they were homoligated????
I'll buy a LED H4 and see what they are like and report.
As you said Jim, it has to be safer to have a bright LED than a low rev dull incandesent bulb.

graeme