6v to 12v Step-up convertor for headlamp?

[Butch (cb)]

Keeping enough electric power for running around town at night or with the light on, is a struggle for the old dynamo system.
The engine need revs. To charge and feed the electric consumption.
If you fit a step up unit you lose even more power. Please bear in mind that the voltage step up unit need cooling, and air circulation inside the headlamp I not “impressive”.
The way to 12 volt is a new 12 volt armature and 12v regulator. ( or Alton generator ).

Why not fit a 6 volt LED headlamp, and 6 volt LED rear light bulb. To ease load on the feeble dynamo system.

I've got LEDs at the back and also for my pilot light. Pilot is bright enough for around town work.

[Greybeard]

That may seem like very low efficiency of about 60%, but this does make sense for this type of unit.

The converter here is 400 W rated. The efficiency figure provided will almost certainly apply to somewhere near full output power. Because of the standing power consumption of the converter (regardless of load it will draw current for internal consumption) the efficiency falls at lower output levels.

This can be compared to the old truism that all engines are at their least efficient at idle. No useful output, but some fuel burnt in running the engine.

I don't understand most of that. 

I'm not planning to keep the converter powered when the headlamp is off.

Bottom line; If I use this device to power a 12v headlamp bulb will it cause problems on my 6v machine? What Wattage bulb should I be buying?

[Greybeard]

I've obtained the User Manual for this DC-DC Converter. If anyone is interested I've attached a copy. Needs a PDF reader.

[metalflake11]

Hello Graybeard. Sorry, but this wont be the most positive (no pun intended) post on this thread.
Firstly, a belt conversion does not give you 12volts, it simply spins the dynamo faster, and makes it start charging at lower engine revs.
Secondly, removing its heat sink and expecting the battery box to do the job is asking for trouble in my opinion. If it is as large as you say it's because it must produce a lot of heat (by using lots of electricity!) and that heat needs to be dissipated efficiently.  Even if the box is 85% efficient (which I very much doubt) why not increase the 6v headlamp bulb by the other 15% for the same power usage?
Thirdly, if it is not completely waterproof I can't see it lasting very long before there's a malfunction or even a small fire.
In your situation I would clean all my electrical connections and switches first, and check your reflector against a new one to see if it's dulled with age.  There is no reason why a 6v system should not give you perfectly bright lights. Give this a Google and you will see that these simple tasks can transform your lighting.
To sum up, you seem to be over complicating your electrical system and wasting power in order to get a heat sink hot. (or if you remove it court disaster.)
Sorry to be so negative. (pun intended)

[Greybeard]

Metalflake, thanks for your input I really appreciate hearing from people who know more about this stuff than me 

Firstly, a belt conversion does not give you 12volts, it simply spins the dynamo faster, and makes it start charging at lower engine revs.

I'm not considering a belt conversion

Secondly, removing its heat sink and expecting the battery box to do the job is asking for trouble in my opinion. If it is as large as you say it's because it must produce a lot of heat (by using lots of electricity!) and that heat needs to be dissipated efficiently.  Even if the box is 85% efficient (which I very much doubt)

The description of this gizmo offers up to 400w of output power hence the large finned heat-sink. In the manual it states that the maximum output power is ten times the input voltage, so 400w can only be achieved with a 40v input voltage. In my case the absolute maximum power would be 6v x 10 = 60w. My feeling is that there would not be a heat dissipation problem. While testing on the bench yesterday I used the only 12v bulb I had, which is a 12v 21w indicator bulb. The heat-sink didn't even feel warm during that test. I'll get a proper 12v headlamp bulb and see how that goes.

why not increase the 6v headlamp bulb by the other 15% for the same power usage?

Can you explain that please. Are you suggesting that I use the converter to increase the voltage to the existing 6v headlamp bulb? TT says that a 12v bulb needs 14v, so maybe 6v bulbs will burn a lot brighter with a small voltage boost.

Thirdly, if it is not completely waterproof I can't see it lasting very long before there's a malfunction or even a small fire.

I believe that I can keep the device dry in the toolbox

In your situation I would clean all my electrical connections and switches first, and check your reflector against a new one to see if it's dulled with age. 

My battery, switches and loom are all very low mileage. The headlamp reflector may need changing; I've been thinking about that actually.

There is no reason why a 6v system should not give you perfectly bright lights.

But it's not good. I bought a 6v halogen bulb but it is still not good enough. I have to ride slowly in the dark because the light beam is not bright enough.

[metalflake11]

Hello again!
Right, ignore the belt stuff, it wouldn't make any difference to bright lighting anyway.
The over heating stuff needs to be tested with a much bigger bulb as you say, let us all know how that goes.
You may be able to put in a waterproof place, but as it cools down condensation will form and it will end up wet unless the unit is completely sealed.
 Another point is vibration on the bike, is it B.S.A. proof in that department?
Your battery if fully charged will be sending more that 6v to the bulb as it is, (I think about 7.5v, a fully charged 12v battery is actualy 13.6v) so putting even more volts to it would make the bulb go 'pop'. What I meant was, instead of wasting electricity powering the 'gizmo' just put a higher wattage bulb in for the same net take from the charging system.
Mileage has nothing to do wiring condition, it's age! Bad connections due to that will sap the power through the system. Pull a few apart and check for dullness and see if they have gone furry, cleaning them up could make a huge difference.
If you have any doubts about your reflector, check it against a new one before you do anything else. It's amazing how they can look ok on their own, but dull and yellow next to a new one. Again, that will make a massive difference.
If, as you say, you've tried a halogen bulb and have a good battery and charging system it's your connections, your lens, or a combination of both if your headlight is that poor.
Ask away if you have any more questions.

[Greybeard]

The over heating stuff needs to be tested with a much bigger bulb as you say, let us all know how that goes.

I will.

You may be able to put in a waterproof place, but as it cools down condensation will form and it will end up wet unless the unit is completely sealed.
Another point is vibration on the bike, is it B.S.A. proof in that department?

I cannot answer those points yet

Your battery if fully charged will be sending more that 6v to the bulb as it is, (I think about 7.5v, a fully charged 12v battery is actualy 13.6v) so putting even more volts to it would make the bulb go 'pop'. What I meant was, instead of wasting electricity powering the 'gizmo' just put a higher wattage bulb in for the same net take from the charging system.

That's a thought. I was expecting the 6v Halogen bulb, (I think it's 35w/35w) to be far brighter than it is.
As I've bought this gizmo I'd like to try to make it work.

Mileage has nothing to do wiring condition, it's age! Bad connections due to that will sap the power through the system. Pull a few apart and check for dullness and see if they have gone furry, cleaning them up could make a huge difference.

When I say mileage I mean time as well. I renewed the wiring harness, switches and battery when I restored the machine a couple of years ago. The lights were no better then than they are now! The reflector however has been on my garage shelf for 40 years and although it's not obviously deteriorated it's a Wipac pattern reflector so maybe not trustworthy.

If you have any doubts about your reflector, check it against a new one before you do anything else. It's amazing how they can look ok on their own, but dull and yellow next to a new one. Again, that will make a massive difference.

I've just ordered a new Lucas 700 reflector with 12v 45w/45w bulb from Paul Goff

Ask away if you have any more questions.

Thanks fella

[metalflake11]

OK! To finish my input for now, try the 6v halogen in the new reflector first, to might be very impressed!
I had the use of a 750 Bonnie for a bit a while back, terrible lights on that for what it was. (Alternator etc.) I changed the reflector for a new one and it became everything Joe Lucas hated...........Brilliant! Literally.
Good luck.

[duTch]

 Hiya G.B, I'm fairly interested in the progress of this, as it seems your main mission is to up the wattage output (brighter lights)with minimal current draw...but (maybe as so the other comments) I can't see that a higher voltage output will be any advantage...given the current draw to run it...?
 I'm running a halogen 35/35 in a new Hella H4 (motorcycle) reflector and it's ok in ambient town lighting- I think... but I need to check (hand in front of) occasionally to see if it's working ...I'm thinking your 45/45 would be an improvement if on 6V, but being on the 12v setup... ..

 I'm inclined to think as MF says

  Even if the box is 85% efficient (which I very much doubt) why not increase the 6v headlamp bulb by the other 15% for the same power usage?

I'm thinking to do that, but will have to wait until November 'till the supplier gets back from his GB/Euro holiday...

 With my limited knowledge of electrics, My system seems to provide a fairly constant ~7.2 volts at anything past idle, so if I was to go to a 50/65W, the genny would be working almost full capacity, but if it's there it needs to earn its keep ...I'd forget about the 400W of that unit though..that's a bit(lot) dreamy, as you're still governed by your battery capacity, and the Genny/Dynamo ability to keep the amps up...

 Watts is Watts- I have a 50/65W on the (12V) Guttzi for around town, and it's ok but have a 90/100W for out of town and it's great but challenges the system in town (as per my blurb at the bottom), currently running through a Narva H4, but the Hella H4 seems to have a better spread pattern.
 I also have a Lucas-'TVS'(Wasell ) 700 series "Foreign Headlamp" that I'll compare, maybe tomorrow....have wrong connectors!

[Greybeard]

Hiya G.B, I'm fairly interested in the progress of this, as it seems your main mission is to up the wattage output (brighter lights)with minimal current draw...but (maybe as so the other comments) I can't see that a higher voltage output will be any advantage...given the current draw to run it...?

Of course that must be true; 'you don't get owt for nowt', (north country saying) but when I checked my 6v lighting, (engine not running), all lights on it was drawing less than 5amps. I make that about 32Watts. If this gizmo can give me a good headlamp, (that's all it will have to do) for the fairly short runs in the dark that I do I reckon that my system may have the power to run the converter.

I'm inclined to think as MF says

  Even if the box is 85% efficient (which I very much doubt) why not increase the 6v headlamp bulb by the other 15% for the same power usage?

I'm thinking to do that, but will have to wait until November 'till the supplier gets back from his GB/Euro holiday...

With my limited knowledge of electrics, My system seems to provide a fairly constant ~7.2 volts at anything past idle, so if I was to go to a 50/65W, the genny would be working almost full capacity, but if it's there it needs to earn its keep ...

I did buy a Halogen 6v bulb, 35w I think; it made no real difference to the light beam.

I'd forget about the 400W of that unit though..that's a bit(lot) dreamy, as you're still governed by your battery capacity, and the Genny/Dynamo ability to keep the amps up...

No, the blurb for this thing says that the power output is ten times the input voltage. The maker claims that 400w can be obtained with a 40v input. With a 6v input I should max at 60w

I'm having trouble understanding the pidgin Engrish to programme this piece of equipment. I've just bought a brand new Lucas 700 reflector/lens that came with a 12v 45/45w Halogen bulb so have been playing on the shed bench with the battery off the BSA. The output from the converter is adjustable, (voltage and current). The bulb shines lovely and bright at 14v but now shows some discoloration inside the glass so I may have overloaded it. Whoops!

I've just been outside again. I set the output voltage from the converter to 13v, and the bulb current to 3.5 amps, (obtained from this calculator http://www.supercircuits.com/resources/tools/volts-watts-amps-converter) and put my digital meter in series with the input to the converter to get the current from my 6v battery. The meter is showing a load of 7.7 amps. So a 45w headlamp bulb is using less than 8amps. Remember this is just the battery, so in the bike with the dynamo helping I should get a higher voltage. Does all that sound ok to you chaps?

Before I do anything else I must test the new reflector/lens with my existing 6v headlamp bulb to see if it makes a noticeable difference.

[sparx]

  You would be better off with a 6v 45/45w bulb. It would draw less current from the genny/battery with there being no efficiency losses through the converter (which I assume are mainly transformer losses), and if the converter should pack up in the middle of nowhere you would be up sh*t creek without a paddle waiting for daybreak instead of just popping a new bulb in.
   I'd reserve the converter for stuff that will only run on 12 volts, such as a sat-nav or phone charger.

[Greybeard]

You would be better off with a 6v 45/45w bulb.

If it's that easy why do so many owners convert to 12v?

It would draw less current from the genny/battery with there being no efficiency losses through the converter (which I assume are mainly transformer losses), and if the converter should pack up in the middle of nowhere you would be up sh*t creek without a paddle waiting for daybreak instead of just popping a new bulb in.

Good point, but I'd just ride slowly on the 6v LED pilot light that I have; It's quite bright. Did my figures horrify you then?

I'd reserve the converter for stuff that will only run on 12 volts, such as a sat-nav or phone charger.

I was told yesterday that I may be able to get away with running a SatNav from the bikes 6v, (probably 7.5v when running) supply.

[sparx]

If it's that easy why do so many owners convert to 12v?

 I'm not saying there are no advantages to having a 12v system, just that I don't think a converter is a good idea for running a headlamp.

[/quote]
Good point, but I'd just ride slowly on the 6v LED pilot light that I have; It's quite bright. Did my figures horrify you then?

 Not horrify , no, just can't see the point of adding unnecessary equipment that could  fail at some point. Plus a 45w 6v bulb is just as bright as a 45w 12v bulb, and would draw less current than the 12v bulb being supplied from a converter. The only advantage I can see is that if you put the converter in the toolbox it would keep a spare pair of gloves nice and warm.

[/quote]
I was told yesterday that I may be able to get away with running a SatNav from the bikes 6v, (probably 7.5v when running) supply.

You probably could. A lot of electronics stuff runs on 5v. Worth trying it on a "suck it and see" basis.

[duTch]

Plus a 45w 6v bulb is just as bright as a 45w 12v bulb, and would draw less current than the 12v bulb being supplied from a converter.

 That's the point I was trying to make...

"My system seems to provide a fairly constant ~7.2 volts at anything past idle, so if I was to go to a 50/65W, the genny would be working almost full capacity,......
 ...I'm thinking your 45/45 would be an improvement if on 6V,......
..Watts is Watts- I have a 50/65W on the (12V)"

I was told yesterday that I may be able to get away with running a SatNav from the bikes 6v, (probably 7.5v when running) supply.

You probably could. A lot of electronics stuff runs on 5v. Worth trying it on a "suck it and see" basis.

I've also considered that, but it may need a 5v regulator, but I also discovered that they may need a couple of volts difference to work properly, but I know just enough to be dangerous with that

 One other thing I thought of earlier, my neighbour finally hooked up his LED spotties on his fourby, and they light up daylight ....true

 So my point is maybe consider finding a couple of bike sized ones of those in different lumens/candlepowers and run them from the 12v, one for high beam and one for low beam-  as accessories.....that way you don't need to worry about legalities...??

[Johnny J]

I also don't really see the point of a 12V-converter and using a normal bulb, reason I did it was to be able to use a LED headlight bulb.
Draws only 20W and is equal to the light output of a 55W normal one...