Homemade *bright* LED light setup

[Haku]

I have added homemade LED lighting to my Urban Mover UM36 which are 'stealthily hidden' in the bike's reflectors and power off the bike's battery, without having to alter anything on the bike to tap the power from the battery:


It was easier to do than I first thought so I'm writing up here how I basically do it 'from scratch' because what I have at the moment is working very well but it's a mess of wires, not weatherproof and no on/off switch.

The main advantages of creating your own light setup this way are: you get to decide how bright the lights are, no worries about replacing batteries, no worries about remembering to put the lights on your bike - they're always there, they don't look like traditional lights so the chances of someone stealing them isn't so high (or easy), and as flecc said you don't line the pockets of bike light companies that sell lights more expensive than whole bikes.

Over the next couple of months (just a guess) I'll be posting pictures, info on what bits I bought from where and how I fit it all together.

Just in case someone follows what I'm doing and makes something break or go bang; DISCLAIMER: This is how I am doing things, any modifications or additions you undertake to your bike you do so entirely at your own risk, I will not be held responsible for others actions.


To start the ball rolling I've just ordered two step down adjustable switching regulators for about £16 the pair which can take my bike's 26v battery down to a sustainted voltage anywhere between 1.25v to 13v, which eliminate the need for calculation and use of resistors, the lights won't dim when the battery goes down and I can use a few or a lot of LEDs without doing any complicated wiring or recalculation of resistors values needed.
I've also just ordered 30x 55,000mcd 5mm bright white LEDs for about £6 as the 7 ones I'm using now are only 12,000mcd and can light up a dimly lit road and cyclepath ok but I want a BRIGHT front light

Other bits I already have are; rear reflector, front reflector, super bright Toshiba red LEDs (cost about £1 each from Maplins! but they were leftover from a project years ago, if you need some - eBay), handlebar reflector mount which will be used to hold the box of electronics & on/off switch.


edit: removed link to 55,000mcd LEDs as they're no good for this project, they use 40% more power than these (which are the ones I have used in the prototype and will use in the final) and they aren't 40% brighter.

[Haku]

Today I got to use a small milling/drilling machine to drill the 5mm sized holes in the front reflector for the LEDs, using such a machine ensures that all the LEDs point in exactly the same direction to give you a spotlight effect.





Using masking tape & a digital micrometer to mark out the spots where I wanted the LEDs I then drilled them, only one LED can be used in the middle of the reflector because of the mounting points (that can be seen on the back images). The masking tape came off in one piece (which was nice). Not all the holes were precicely aligned down to the 1/10 millimeter but that's ok because when the LEDs are installed and switched on you won't be able to notice.

I had to spin the drill at high speed and drill down slowly so the front doesn't crack, my first attempt by just using a hand drill cracked the front in half but being glued to the black back it didn't fall apart.

[Haku]

Today I received the Adjustable Step Down Regulators, I'll only need one for this project but it's such a useful device I bought a spare, they can take up to 30v input so fine for 24-26v batteries but unfortunately no good for 36v battery setups. But the nice thing about using one of those DC-DC converters for your LED setup is you don't have to use your bike battery, you can easily use a 6 or 8 cell battery pack instead without having to re-calibrate the voltage going to the LEDs as the DC-DC converter outputs the same voltage for the LEDs no matter what the input - so long as it's higher than the voltage used for the LEDs plus 1.3v, so powering 3.4v LEDs you need a minium of 4.7v input.
Another good reason (besides simpler wiring for the LEDs) for using this DC-DC converter is that your lights will remain the same brightness when your bike's battery runs low, I ran mine completely flat recently to help cycle the individual cells inside (battery's running better now), my prototype front light setup remained bright even when the battery could hardly power the motor.

The small black box I'm using to house the switch and the DC-DC unit is from Maplins, part number N78BQ, it's not rated as waterproof but running it under the tap didn't show any leaks, I had to completely submerge it in water and shake/tap it before a couple of drops got in - so I'd say it will be fine for rainy conditions with a little extra care when making it. It will be mounted on the handlebars with the mounting that came off the reflector as my bike already has a reflector mount that goes on the forks.

The switch is also from Maplins, it's a Sub-Min Toggle E as I had it already but the A type is all that's needed, I'll be getting a waterproof cover for it when I can next get over to the store.

[Haku]

The last heavy downpour a weeks ago ruined the LEDs in my prototype back light because I hadn't waterproofed it (well it was supposed to be summer, as in sun, sun, more sun and only sun) so I ordered some new bright red LEDs from an eBay seller here. I accidentally ordered 3mm instead of 5mm but they're just as bright so no worries.

I wanted to avoid using resistors as much as possible to make things easier to wire but I can't avoid using them for the red LEDs. The white LEDs are 3.4v max but running them at that level isn't good for them as they can get hot and burn out so I set the DC-DC output to 3.15v, so then to power the 1.9v red LEDs from that 3.15v I'm using a single 68 ohm resistor inline for each of the 4 I'm using.

Here's the whole wiring diagram of the project (simple, isn't it):

[Haku]

17 LEDs now superglued into the front reflector, I had to drill a 7mm hole in the back plastic for the very middle LED so it would stick out of the front instead of being recessed which would cause problems with the mounting bracket:



Next to do is solder all the LED leads together, which is where I deviate slightly from the wiring diagram above, in the future I might setup the front light so it can have a 'low' and 'high' beam by only powering just 5 or all 17, so to do this I'm going to wire the '+' line of 5 LEDs in a separate circuit, but normally I'd just wire all the '+' legs together (along with all the '-' legs together).

[Haku]

Small update (no pics this time), I wired up the LEDs in the front reflector and temporarily attached it to my bike, it still needs some proper wire attached to it (having a little difficulty finding just the right type) and also waterproofing.

But holy smokes is it bright! one minor annoyance is that the reflector can be angled up/down but the notches are just a tad off for my liking, I can either point it slightly down which won't dazzle anyone but it doesn't fair too well along unlit roads & cyclepaths, or I can point it directly forwards which works extremely well along unlit roads & cyclepaths, I can see *everything* in front of me (reflective roadsigns glow suprisingly bright even from a distance) but it also means anyone in it's beam can be dazzled.

Could I get into any trouble by having it point directly forward?

I also found I had to turn the voltage down from 3.4v to 3.15v as the LEDs were getting quite warm and a couple showed signs of colour shifting to blue as 3.4v is pushing them to their limits, also the DC-DC regulator gets a little warm so I wouldn't power more than 30 LEDs from it, though 17 really is enough for a front light

[Haku]

...and those are taken in the daytime...

[ITSPETEINIT]

Originally Posted by Haku

.

But holy smokes is it bright! one minor annoyance is that the reflector can be angled up/down but the notches are just a tad off for my liking, I can either point it slightly down which won't dazzle anyone but it doesn't fair too well along unlit roads & cyclepaths, or I can point it directly forwards which works extremely well along unlit roads & cyclepaths, I can see *everything* in front of me (reflective roadsigns glow suprisingly bright even from a distance) but it also means anyone in it's beam can be dazzled.

Could I get into any trouble by having it point directly forward?

I don't know how expensive this was to make, or whether there is enough room for two of these reflector lamps on the front of the bike. If you had two and a toggle switch to switch from one to the other so that they were not both on together, that would solve the problem of dazzle on the one hand and good lighting on the other by 'focusing' each on their particular job requirement.
Very sophisticated.
Regards
Peter
PS giving you full marks out of ten for your 'invention' and quality work, I don't know how I have got the audacity to suggest improvement.
You are going to have a proper 'flight deck' soon.

[Haku]

I don't want to add more reflectors to the front as I want the whole setup to look like there's no whole setup - hence embedding the LEDs into the reflectors.

The thought of two separate lights, one pointing forward & one pointing down, had crossed my mind but that would mean getting hold of another reflector & somehow fitting it onto the bike so it looked like it was meant to be there and not an added accessory.

Hindsight is such a wonderful thing (why can't someone invent the opposite equivilant? ), because if I'd really thought about it I would have drilled some of the LED holes at a 15degree downward angle so I could have high & low beams through a switch. But, when I wired up the front LEDs I put 5 of them on a separate circuit so they can be turned off/on separately from the other 12 (the center one and 4 on the corners which you can see the legs of in the below picture), which would act as a high/low beam setup with the right switching arrangement (5 shining in your face isn't very bad at all, all 17 is though)

For the moment I've set it up so all 17 will be switched on/off with one switch as there's not enough space inside the plastic box for a 2nd switch and the 3 position switch I do have is no good, it can be easily accidentally switched off with a little knock of the lever.

A couple of pics of the initial LED leg wiring, the ground legs are flattened down and all attached together, the positive legs are bent over a few mm above the ground legs so they're not touching:



The whole lot will be 'encased' by using a glue gun as it'll cover everything and make it hopefully very waterproof, then sprayed or painted black so the light doesn't come out the back.

[Haku]

Working on how and where to mount the small control box containing the on/off switch and the DC-DC converter I've come up with this solution, using the reflector mount that came with the reflector (there's a different one already on the bike that the reflector light uses) it almost looks like it was designed to be there: