need help with buck puck and lux i's

http://www.leddynamics.com/LuxDrive/datasheets/3021-BuckPuck.pdf

this is the data sheet i am using. i am slightly (well maybe more than slightly :thinking: ) confused. i will be running some lux I's in an motorcycle application (same as auto 12.5-14 VDC system)
as i read the spec sheet i noticed you can use this to dim the luxes or strobe them . which would be prefered, strobing them or just dimming them. lumileds says on their spec sheet that weird things happen when u just dim them. can anyone enlighten me?

also i kinda understand how you can run a few in a series. u dont understand though what decideds how many in a series, and how many parallel you can go. i also dont see how the same 700ma driver can drive 6 lux 1's and then drive 12 lux i's (doesn't each one pull 350 ma, so are they aniemicly underdriven?)

i will be using 1 array 9 lux I's red with buck puck and 2 arrays of 2 lux I's red-ambers with buck pucks. i want the red array to do a 250% increase in brightness from its dim setting to full, thinking 150ma per Lux at dim and 350 at full. If i strobed it how would that work? run them at 350ma and run at 40% duty cycle (hope thats what its called)?

by strobing I guess you mean PWM? By using PWM the color is less likely to shift. By diming by just reducing current, the color will shift.

If it puts out 700ma, and your input voltage is say 12, and your luxeons pull 700ma at 4 volts, then 3 wired in seires (3x4volts) would be the max you could run in series to have them all pull 700ma. Now if your input voltage was higher (car on) then it's obviosly different.

When you wire them in parallel, they would get the 700ma divided between them (since the regulator will only output 700ma). So 2 lux1 in parallel would be 350ma spec for them. Say your lux1 pulled 350ma at 4volts, then you could have 3 sets of 2 paralled, with the sets in series, for a total of 6 luxeons...

ok just to double check my work here so i dont just blow my money watching lux i's explode. my electrical system varies from 13.6-14.5. the lux that will be used is 2.31 vf min and 3.51 vf max 350 ma... the buck puck says go 2 volts over total needed vf... so i will do 2 parallel sets of 4 on a 700 ma buck puck.

on another note... does this use 8.4 watts? (3vf * .350 a=8.4w) i just have to keep note to how much i am freeing up

thanks for clearing that up for me though... i feel much better bout using them now.... i cant wait till i get them in.

2 leds wired in parallel, assuming they both have the same vF, when hooked to the buckpuck constant current which limits 700ma output, each see 350ma. Make sure the leds you use both have the same bin (vf bin). For instance you don't want to pair a QY0L and a RX0H, as the RX0H would pull most all of the current, and the QY0L would hardly get any.

Now, to be safe that they will be lit up at the max current (350ma each / 700ma per pair) no matter what the situtation, take your lowest voltage from the bike (~13.6 when running) and divide by the highest Vf range of the bin of your led (you said 3.51 max) gives you 3.8xxx. That means you'll always have full power if you have 3 in series. Since the number is almost 4, you could also go with 4 in series but under less than ideal conditions they wouldn't be at full power and would drop out of regulation and into "direct drive". That depends on the actual Vf of the leds, and what your alternator is putting out...

You could wire 3 leds in series. and another chain like it in parallel, and connect both that way and get the same effect too. like:
neg buckpuck wire....-led+...-led+...-led+...pos buckpuck wire
......................^....-led+...-led+...-led+....^

You could probably get away with 4 in series depending on your led Vf, but 3 will ensure it stays in regulation at all times even at 12volts (bike off).

And yes watts is volts * amps. So, .700a *(3*3.51v)=7.371watts to the leds.

thanx for the help... i will either do a 3x2 array(700ma buck) or a 3x3 array(1A buck). just got in touch with lumileds. they said to get binned ones to try futureelectronics.com so i will try them tomarrow and hopefully order parts then. i hope to have all the parts by next weekend so i can start work. now for my other task at hand.... some led driving lights, but i will start a new topic. again thanks:rock:

Hey try PhotonFanatic on here. He sells binned ones. Future won't sell you binned unless you order like 100's and 100's of them. PhotonFanatic has some good luxIII ones.

thanx, i am chacking to see if he has any lux I's, i did the math. if i use lux I's over III's. i will end up over all with more lum/watt... plus i figure it will spread the light out a lil better