DIY light virgin needs HELP

[Mickey Blue]

Hi All

As the title says I am a DIY light virgin, but spending $500 on the Ay-ups that have caught my fancy is ridiculous.

I'm working long enough hours at the moment to put my commute home into darkness, and also long enough to prevent me going through all the forums looking for the answers I need. I also don't have any real amount of electronics knowledge either. So the end result is that I come to you lovely people.

I am hoping to achieve:
500 – 700 lumens
A small light: that will be on the bars, with an on/off and half power switch
A small battery: that will be connected to the stem
5 hours of battery life at full power
Waterproof

I know this combination might be unlikely but this is my goal. Any thoughts / adjustments / feedback on this list is appreciated. Do I use buck pucks? A Fat-Man? 14.4V? 12V? 2 crees? 6 SSCs? Parallel or series? Can I have a set up that sidesteps the heat issue, removing the need for heatsinks? etc

My range of tools is also limited so I won't be using anything more than basic back shed tools.

Sorry this is so long and big thanks in advance.

Michael

 

[LukeA]

What is the intended power source?

 

[znomit]

I am hoping to achieve:
500 – 700 lumens
A small light: that will be on the bars, with an on/off and half power switch
A small battery: that will be connected to the stem
5 hours of battery life at full power
Waterproof

I know this combination might be unlikely but this is my goal. Any thoughts / adjustments / feedback on this list is appreciated. Do I use buck pucks? A Fat-Man? 14.4V? 12V? 2 crees? 6 SSCs? Parallel or series? Can I have a set up that sidesteps the heat issue, removing the need for heatsinks? etc

My range of tools is also limited so I won't be using anything more than basic back shed tools.

You need 3 Q5 crees running at 1A for that much light(about twice the ayups 320lm output).
14.4v 5Ah battery.

Given you don't want to put too much time into it and dont have too many tools Id go for the cutter triple kit with the housing for $230 odd and add your own battery. Narrow optic for road, medium for MTB.

 

[singlespeed10]

IMHO, 500-700 lumens is overkill for commuting and will just require a big battery unless you are using a dynamo. I also commute in the dark and am now using a single SSC P4 with a medium optic. It casts an adequate light down the road and is wide enough that I can be seen from an angle. A 2-LED setup - one narrow and one wide would be better but 3 seems unnecessary for commuting and would just require a bigger battery.

The response that you got from achesalot on MTBR was great advice, and you will find that that he is a god on that forum. His web site is awesome and is a true classic! I personally think that SSC is the way to go as they are a little cheaper than Cree and it is much easier to obtain a wide selection of optics quite cheaply [http://www.ledsupply.com/20mm.php] - Luxeon optics SSC whereas Cree does not. Ledsupply is in VT so that shipping takes a couple days.

A design that is very easy and cheap to build and looks great is the Dinotte-Style light [http://forums.mtbr.com/showthread.php?t=368896]. This works best for roadies as it is a single LED light although you could very easily mount two on a handlebar.

Happy building.

 

[Calina]

Check out Dom's and Ktronic's threads and look at the Min-T light.
http://www.cncdelite.com/
If you want to go the dyno way, check Martin's site: http://www.pilom.com/BicycleElectronics/BicycleElectronics.htm

Also, have you seen the Scolo: http://www.cpfmarketplace.com/mp/showthread.php?t=174344

 

[Mickey Blue]

Thanks for the comments guys

Intended power source? No real idea, something premade ideally.. what about RC batteries?

Maybe 700 lumens IS overkill for commuting.. I currently have a fenix l2d ce torch that puts out 140 lumen and I want more. I imagine 2 of what I have might do ok, but three would be better, so the result is 3 cree's, aka the cutter MR11 kits that I was already looking at. But I'm not writing off the SSCs at all.

The dinotte diy looks easy enough for me to make, would there be any problems with the cutter kit being housed like that? Heat issues? Would running the MR11 kit at 700mA remove the heat issue with an increase in light?

Also, a general question: buck vs boost – Is this thinking right, buck needs bigger batteries, boost needs smaller batteries to achieve similar burn times with the same LEDs? what i'm leaning towards is gilbo's MR11 light which uses a fatman(http://forums.mtbr.com/showthread.php?t=337752) but dinotte style.. thoughts?

 

[Jarl]

A buck converter knocks down the voltage so it's suitable for the LED's.

A boost converter increases the voltage so it's suitable for LED's.

If you have a string of 10 LED's on a 20V power source, you need a boost converter.

If you have a string of 3 LED's on a 20V power source, you need a buck converter.

If I were in your position, I'd buy 3 18650 cells and wire them in series, and with 2 LED's at 700ma it'd give you just under 5 hours runtime at full power. (for this you'd need a buck converter)