DIY Bike light

[SMSAlmer]

Hi, Ive been searching this forum for a while now, and would like to build an LED light for my bicycle. The links below show the concept.

http://i159.photobucket.com/albums/t132/SMSAlmer/Light1.jpg
http://i159.photobucket.com/albums/t132/SMSAlmer/Light2.jpg

3 LEDs, which I can switch on or off using just one button. These will be attached directly to the lid, with the drivers and batteries inside a case, attached under the stem. The case will be machined out of aluminium using a vertical axis CNC mill.

I was thinking of lenses with 3 different beams, Wide, medium and narrow. The requirements of the overall thing:

-Inexpensive
-Powerful
-Efficient

Of course, one is a tradeoff to the others, but, what components would make the best bet?

I know little about electronic and optical stuff, so here I really need help.

What about Cree LEDs and mobile phone, or small notebook batteries?
What about drivers for the above?
Any link to European online suppliers? (I am from Malta)

I would like to buy off-the shelf components which are relatively simple to assemble. (I would not like to build the circuit myself).

Thank you very much for your time and help,

SMSAlmer

 

[andyslesson]

Hi SMSAlmer,

I've been building and ride-testing my own LED bicycle lights for many years. I use them every day of the year, and I've incrementally honed them so they stand up to the rigours of potholed roads, rain, snow - you name it.

I can definitely recommend off the shelf components; I'm quite handy with a soldering iron and circuit components, but my philosophy is that if anything gets damaged or fails, it's a lot of work to repair custom units/components.

Balanced against that is marginally increased bulk of off the shelf components.

Because I have a seriously bright light set up on my bicycle, I've spent a lot on components, so totalling up the cost of them (excluding the R&D costs for components and designs that weren't optimal) I reckon my existing set-up clocks in at about 100 quid.

To get the equivalent durability and brightness from an off the shelf bicycle light would have cost me hundreds more and I wouldn't get got a set exactly tailored to my requirements. If you want to know more, message me with some questions and I'll do my best to answer.

Stay safe, be seen

Andy

 

[SMSAlmer]

Thanks Andy, that was quite an eye opener. Seems then, this is not that bad an idea. 100bucks is a baragain i think!

My intension was to use one switch to toggle between one, two, or all three of the LEDs simultaneuosly on.

Being able to control the power output (ie between 350mA, 700mA and 1A) of the LEDs would be nice, but that I believe would be complex.

Having said that, i have some experience in soldering. It is more about circuit design that I'm not very knowledgable at.

Also, I was thinking about Ledil Lenses. (Are these a good option?)

7deg smooth spot for fast riding,
15-25deg medium
and 30deg, or oval, for slower riding, and to illuminate around the bike.

I did a search, many good examples, would like to know more about control circuits though.

Thanks again!

 

[SMSAlmer]

My thinking was that using 3 LEDs with different lenses, I could use the one with the narrowest beam ONLY when going fast and in very dark places, hence saving battery life.

However, it seems that most lights use one single driver to drive multiple LEDs in series.

Is this because its more practical/efficient?

 

[andyslesson]

Hi SMSAlmer,

3 leds doesn't sound nearly bright enough to me, but then we all have different requirements (mine is to be seen when filtering in amongst rush hour traffic, I don't really need to see where I'm going because I cycle in a city, and there's streetlights all of the journey)

Rather than use discreet leds, have you considered using a ready made light unit? By that I mean something like an led spotlight for ceilings, or whatever? MR16 or MR11 I think's the correct sizing for the units I'm describing.

They tend to come in different angles of light dispersal ranges (narrow, wide and so on) and different colours and flashing too...be careful, tempting as it may be, resist the temptation to go for blue flashing units ;D The traffic parts like the Red Sea, but the local law will have something to say about it

As for the toggle switch to switch between one, two or all three on. Yep. Can be done. On my front light unit I've got a 3 position toggle switch that does exactly that.

To give you an idea of what's possible here's my setup:

Everything's 12v which makes it easy to get DIY/car components for.

Front
Two high power white MR16 narrow beam spots in the centre, always on, each units includes a lens/focusser out-of-the-box.

Two wide angle white MR16 floods on the outside of those. Can be toggled flashing/constantly on/off (I have them on the outside, nearer the grips, so the bike looks "wider")

Back
One wide angle red MR16, linked to the front floods, so it can be flashing/constantly on/off.

A home made bottle battery runs the lot. I have two of these - one always on the shelf fully charged and ready to go while the other one's in use on the bike.

Both bottle batteries are the same - 8 x 2.7 Ah high capacity rechargeable AA Nimh batteries in each, with AA sized battery holders so the batteries can easily be removed/replaced and recharged using 2 smart AA charge/dischargers that take 8 AAs at a time and dis/charge each one individually.

The bottle batteries use standard phono connectors for connection/disconnection and ease of removal and changing when they need charging. The bottles fit inside a standard sized bottle cage too.

Then there's the flasher unit. You can get MR16's that are made using flashing leds, but that means they flash out of synchronisation if you have more than one (I have 3 - two front and one back). So I opted for a flashing unit that comes from emergency vehicles; it's designed to flash 12v led units, and you can change the flashing pattern too. Awesome

The icing on the cake is that the whole lot is toggled on/off using just one switch

Oh, and if using MR16s or MR11s, quite a few of them come sealed (glass bits on the front), so no need for additional protection from the elements. And they're both just the right size to fit inside 1/2 or 1/4 " plumbing fittings and the caps to the fittings still screw on to keep the units in place

The flashing unit for the emergency vehicles is the bulkiest component; that doesn't seem to fit nicely anywhere, so I end up having it strapped to the top-tube near and handlebar stem. Once I've set the pattern on the unit, I tend to stick with it, so having such flexibility is kind of unneeded now, so I'm currently in the process of trying to find a smaller 12v flasher unit, but as it stands, I've been using the whole set up constantly for over 3 years without problems.

It's even been crash tested a few times and not taken any damage - it's just kept on working. The added benefit of using MR16s or MR11s is the standard plug fitting for the light units too.

Hope that's given you some ideas and inspiration...and if you find a smaller 12v flasher unit, let me know

Andy

 

[SMSAlmer]

Very interesting setup. Any pics?

In actual fact, running 3 Cree R2s at 1A gives 242lum each. So on paper thats about 750. Anything above 500 is good enough for me. Would like to keep things simple!

I just started a thread in the bicycle section,

http://www.candlepowerforums.com/vb/showthread.php?t=232718

The MR16/11 units are quite tempting, I must say. Seen them, altough the more powerful ones I've seen are not sealed.

Interested in you battery setup. Is it possible to make that at home?
Thanks!

 

[yellow]

2 narrow focus beams, beams going slightly to left and right (a few degrees).
MUCH better than any wider beam focusing.

one wider beam might be ok
(but that with another narrow + slightly offset to the other 2 beams were even better)