Easy DIY Front and back LED lights for Ebikers

[ktronik]

Hey,

getting the hang of the RC stuff...SM is learning me up, thanks mate, here's some back at ya...

and after looking at a few BEC outputs, I though, now that is perfect for powering a AMC7135 LDO reg for the CC drving of LEDs... in English, its a chip that will drive 350mA of constant current, (needed for LEDs) and very is cheap and easy to get...wack em in parallel and you can stack up as many as you like, to build more or less light out the front or back

So you build a 'blinder' out of a 'rail' shaped piece of alloy, wack a few clear bits on front and side and you have a LED waterproof light housing

http://endless-sphere.com/forums/viewtopic.php?f=2&t=13479&hilit=blinder

http://www.candlepowerforums.com/vb/showthread.php?t=194266

So make what ever LED light you need,(ask for directions here) buy some DX AMC7135 (a less than $3) drivers to hook to your red or white LEDs, and power them from your BEC, 5v output, no more DC_DC converter from main pack, as you allready got one, with your RC system!!

easy to get 800lm from 3 LEDs with med drive level..use the 10 deg optics, (can link) and you got a good bright spoty...

enjoy

Ktronik

 

[Bluefang]

You wouldnt happen to have 3 leds and a driver hanging around your place that i can buy? Or a suggested place to buy those items in Aus preferably?

Funny that you posted this information now, I was just about to look for a bike light

 

[spinningmagnets]

I was about to demand pics, but the thread you linked to if full of them, great work!

I like the example with a cordless drill battery as the base for a rechargeable Led bike-light, and I hadn't even considered that the built-in BECs of the ESCs that are becoming popular could be used as a power supply for a bike-light. Very clever, and useful!

 

[ktronik]

Hey blue fang

yep easy to do, could even use BEC if you got a ebike controller, what voltage you trying to use??

K

ps sm: only too happy to help back!

 

[ktronik]

LED basics:

LED are a current source device, and will suck as much current as it can get as so need to be current regulated. opposite to a incandescent bulb... give it the right voltage and it just takes the current it needs and no more....english, LEDs need a LED driver or a ballast resistor to limit the current

So you need LED, driver, optic & housing to make a basic light.

Drivers are normally a 'PWM modulated' current device or a 'CC', constant current device...

LEDs have a colour shift as they approach a higher voltage, this is true for CC drivers but not so for PWM drivers, but PWM are not used in my lights due to the slow 'switch' speed they most work at, as they give a 'flickery' type look... english, both are good, I like CC, and use lower drive currents to get around colour shift.

Some drivers have onboard MCU's and have dimming, some have analogue dimming, some none...some a step up, some step down, for running strings of LEDs from higher or lower voltages (than LED string voltage 'Vf, foward voltage') english, step down is more efficient... so 3 LEDs (Vf 10.5v) run from 14.8v batt using a CC step down regulator. I could run 6 LEDs from 14.8v using a boost or step up driver.

LEDs come in all shapes and sizes, most white LED 'dies' take 3.6v as standard, red around 2.1v... voltage is added to run them in a string (series), current stays the same, current is added if run in parallel, voltage stays the same.
good LEDs come in 'bins' or brightness levels... so given the same current in a R2 bin led will be dimmer than a R3 bin LED... LEDs also come in 'tints' or colour...cool to warm...cree LEDs are the best, XRE, XPE, XPG are all single die LEDs and ones we should work with...Cree MCE & SSC P7 are 4 led dies in the one package, and need a huge reflector to give a nice beam (MS is P7 quad die light) but is a parallel driven one with a cheap driver, so some times suffers from heat related problems resutling form high drive current in the circuit...much better to swap voltage for current any day... but for cheap stuff, low voltage is king!

OK this is what you were waiting for, what is the cheapest way to get it going...

Driver, liner LDO's, cheap and very effieient when close to Vf, and only one $1 to drive a 3w white LED, its a low voltage driver and works from 1S lipo or 5v BEC (OK)
http://www.dealextreme.com/details.dx/sku.3146

LED, cree XRE LED is cheap and easy to work with as it big...

http://www.dealextreme.com/details.dx/sku.2394

one driver will drive that LED at 700ma (~3w)

you clip these 8deg optics to the leds.. nice and punchy beam for going FAST!!
http://www.kaidomain.com/ProductDetails.aspx?ProductId=5253

BTW the back of the LEDs must be on a heat sink, alloy fine, copper better, even wack a LED in the end of a copper end cap, cover it, fit and your good to go...

for all the info you will ever need...

http://forums.mtbr.com/forumdisplay.php?f=124

the only place to troll to get ideas for builds...

DIY today!!!

enjoy

ktronik