DIY conversion of old battery light to dynamo powered

iggs

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Oct 19, 2007
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131
Well well well, I seem to be back here again.

CPF was instrumental in me building my own LED mountain bike lights what seems like many moons ago. I learnt loads and completed an immensely satisfying project.

Back then decent led lights cost the earth and building my own saved me a lot of money as well as meaning I had cutting edge technology on my bars.

The world has changed quite a bit and now led lighting is pretty cost effective. This creates a bit of a dilemma for me. Do I build my own lights or just buy something off the shelf that in some ways could do the job a lot better. In this thread I hope with CPF members help, opinions and advice to firstly answer this question.

I want to add dynamo powered lighting to our city/urban/utility bikes. My criteria for the project are (in no particular order)

The bikes/lights need to not attract unwanted attention and minimise the chance of theft as the bikes sometimes need to be left locked unattended in and around the city.

The lights need to provide lighting that makes the bikes/riders visible and allows riders to see at night in the Sydney environment they will be used in (mainly lit streets but sometimes through unlit parks (Centennial Park)).

They must fulfil New South Wales's legal requirements.

They should be maintainence free, reliable and robust.

The system should be as efficient as possible.

A nice to have would be USB charging for iPhones and possibly other usb devices.

I'm planning to build up wheels using the SP PD8 (disc) dynamo hub and the existing rims on the bikes (700c)

So far the light options I've looked at include

AXA Pico30 Steady Switch Front Light https://www.bike24.com/1.php?content=8;product=39891
At €14 it's pretty damn cost effective

AXA Luxx70 Plus Steady Auto Front Light https://www.bike24.com/1.php?content=8;product=98764
€56 very bright and includes USB charging

I want to mount any rear light on the seat tube but haven't found something I'm happy with yet.

Both of these front lights are approved for use in Germany which means they have excellent cut off to avoid blinding other road users.

They also have very clever features like auto switching.

Interestingly though I have these sitting doing nothing from my previous project

1ac4d7fadcb58e237d4077e4a1854d6d.jpg


Previous project can be found here http://www.candlepowerforums.com/vb...Halogen-to-Cutter-Cree-LED-conversion-project

They are 2 very robust cat eye alloy light heads that I installed MR16 (I think) 3 Cree led and optic units from cutter into. They have good heat transfer pathways and a bit of space for electronics (taskled maxflex drivers currently)

I've seen Martins circuits and also his diy rear light design so I can see that it should be pretty possible

BUT

I'll be honest, I haven't got a clue when it comes to the electronics circuits so I'll be learning from more or less scratch.

AND

I'm new to Sydney so don't know where to buy any of the componentry from.

But the learning is a key part of the game isn't it?

So is it worth investing the time in making my own lights or should I just buy something?

I figure if I was to make something myself it has to do one or both of the following:

1- Give me something suitable for my needs at least as good, if not better, than I could buy

2- be at least, if not more, cost effective than buying. (Ignoring time of course)
 

Steve K

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Jun 10, 2002
Messages
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Location
Peoria, IL
well, the quick answer is that buying the commercially built light is going to be the best option in getting something that meets legal requirements, is built to be reliable, and will be done quickly.

The triple light assemblies that you've got won't be a good match for the dynamo unless you short out one LED (or don't go slow). It will also have a relatively wide beam, which isn't generally suited for road riding.

There are a couple of recent threads dealing with dynamo headlights, but they do require some electronics skills.

Reinventing the wheel can be fun, but there are times when it's just not worth the trouble.
 

iggs

Newly Enlightened
Joined
Oct 19, 2007
Messages
131
well, the quick answer is that buying the commercially built light is going to be the best option in getting something that meets legal requirements, is built to be reliable, and will be done quickly.

The triple light assemblies that you've got won't be a good match for the dynamo unless you short out one LED (or don't go slow). It will also have a relatively wide beam, which isn't generally suited for road riding.

There are a couple of recent threads dealing with dynamo headlights, but they do require some electronics skills.

Reinventing the wheel can be fun, but there are times when it's just not worth the trouble.

Looking at Martins circuits at http://pilom.com/BicycleElectronics/DynamoCircuits.htm there appear to be several options for powering my 3 led system and a tail light

Eg

5e7f0c89e8e395fae5790c6a0ff35d3b.jpg


Or am I missing something?
 

Steve K

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Jun 10, 2002
Messages
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Location
Peoria, IL
I haven't used Martin's circuits, but they seem to be in use by a number of folks. Haven't heard anything bad about them. No harm in playing around with them.

My personal opinion is that three LEDs is about as many as you need in a headlight, so just one of your triples should be sufficient. You might want to try running it as is (with a full wave rectifier, of course) and see how its low speed performance works for you. If it's good enough, then stick with it.
If not, then a simple way to get better slow speed performance is to short out the third LED with a switch. This avoids the issue of the caps used in the voltage doubler circuit.

There are still the issues of whether this would be legal (and if it really matters), and whether the beam pattern is acceptable to you. Throwing it together with a simple full wave rectifier is a rather inexpensive way to get it operating and seeing if the beam is okay.
Personally.... I find that I like a rather narrow beam, usually no more than 4 degrees from the center of the beam to the place where the power has dropped by half. My recollection is that the triple light optics use significantly wider beams. The wider beam means that less light gets placed further down the road and more is placed close to you. The large amount of light close to you makes the stuff further away harder to see, even when the total amount of light produced is equivalent to a well designed dynamo light.

Anyway... build up the rectifier and see how it goes. There's almost nothing to lose! :)
 

Savvas

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Jun 11, 2010
Messages
222
...I reckon 4, 5 or even 6 LEDs is OK - anything below this you can skip the voltage doubler.

Yes - 2 or 3 LEDs are plenty in most commuting situation. Much easier to power at lower traffic speeds as well!

Savvas.
 

znomit

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Aug 1, 2007
Messages
979
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New Zealand
I built a bunch of battery and dynamo lights 5+ years ago. They were cheaper and better than most lights you could by without spending huge dollars. The newer dynamo light however are brighter, tidier and smarter than anything I could easily make.
Its really hard to beat the beam pattern from the dedicated dyno lights, and they provide tail light output too.

For budget city riding I'd suggest getting one of the B&M Eyc models and pairing with a secula tail light.

If you do want to build something (its fun and cheap, and you'll learn a bit too), pick up a cheap XML light from kaidomain or dx, toss the driver and swap out the LED for a 6V XML from cutter, build circuit 5 from pilom with parts from Jaycar
http://www.cutter.com.au/proddetail.php?prod=cut2731
http://www.pilom.com/BicycleElectronics/DynamoCircuits.htm#Boost
http://www.jaycar.com.au//
 

Steve K

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Joined
Jun 10, 2002
Messages
2,786
Location
Peoria, IL
If you do want to build something (its fun and cheap, and you'll learn a bit too), pick up a cheap XML light from kaidomain or dx, toss the driver and swap out the LED for a 6V XML from cutter, build circuit 5 from pilom with parts from Jaycar
http://www.cutter.com.au/proddetail.php?prod=cut2731
http://www.pilom.com/BicycleElectronics/DynamoCircuits.htm#Boost
http://www.jaycar.com.au//

how are the beam patterns on the Chinese XML lights? I'm looking around to find a good host for some experiments, and have been asking around for any recent B&M lights that died. Most of these get returned under warranty, so I've been unsuccessful. Are the Chinese lights close to the same beam quality?
 

znomit

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how are the beam patterns on the Chinese XML lights? I'm looking around to find a good host for some experiments, and have been asking around for any recent B&M lights that died. Most of these get returned under warranty, so I've been unsuccessful. Are the Chinese lights close to the same beam quality?
Not as good a beam pattern because they're not shaped. But you can get a light for 10US$!
 

Steve K

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Joined
Jun 10, 2002
Messages
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Location
Peoria, IL
Not as good a beam pattern because they're not shaped. But you can get a light for 10US$!

A buddy ordered a cheap light from some place in China, and had one sent to me too, just for fun and because it was so cheap. The light uses a LED that fires downward into a reflector and I think there are some front optics. Probably better than the simple symmetrical optics I typically use. I will try to upgrade to a bigger/better LED & better heatsinking and see how it does.
I'd rather put the same efforts into a nice B&M light, though, since it is starting from a better level of quality.

It is amazing, though, how low the price on some Chinese goods can be. I see people buying buck converters and such for a couple of $US. Granted, the components are probably the worst quality and possibly counterfeit, and it might only last 6 months.. but it seems like the price would barely cover the cost of postage.
 

WesleyfuhPP

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Dec 18, 2016
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Moldova
what a cool old dude I hope I am still riding at 80 tell Ron he needs to paint that shroud btw,,,what happened to #2 ???
 
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