Driver for 2 mce's , 7.2v batt & dimmer

[videoman]

I' also trying to put together 2 MCE's powered off a 6000ma 7.2V li-ion Battery using a driver with dimming capability. If I have the MCE's died in parallel and put those two in series, the fV nearly equals the 7.2, what kind of driver ( buck or boost) do I need ? When the battery is fully charged, I read 8.4 volts leading me to beleive a buck is in order (shark 3A). What happens when the battery falls below 6.5 volts? The buck won't work so I am assuming that it will eventually dim out and quit.At that point, I wish I put in a boost driver. If I wire the MCE's in Paralell so that vF is 3.6V to each, using a shark 3A will not supply the 700ma current to all 8 dies but 350ma which is not what I want. Any advice?

 

[zen bicycle]

I would suggest wiring the MCe's in series then the boards in parallel if you can. Much easier to find a driver.

Then you have the maxflex from taskled that will run them at 600ma per die at the highest setting

HTH

 

[videoman]

Mce in series die config would be 14.4 vF, parallel another and use the boost driver. Fine and dandy, what about dimming it ?

 

[Jonster]

I'm looking at pretty much the same thing so this will be useful for me too.:twothumbs

I've a thread running on mods and have been told that whereas a buck driver just drops the voltage, a "boost-buck would allow running the LED at full power still after the battery voltage drops below that of the LED forward voltage."
Have you come across any buck-boost drivers? I'll have a hunt anyhow.

Are you definitely wanting dimmable?
Reason I question is that I'm looking for a 5-mode which for a bike light would give me a change in brightness depending upon whether I'm riding on-road or off-road.
I'm guessing from your login name through that dimmable is essential as you don't want to see flashes of changing light intensity whilst videoing. Also the 5-modes tend to cycle through so to go down a level you have to go up to the top, back to the bottom and back up to where you want to be???

Personally the two drivers I'm looking at are ...
http://www.kaidomain.com/ProductDetails.aspx?ProductId=7947
This is based on cost but I'm not convinced of quality. They also do a non-5-mode for an SSC P7 ?!? For these I'd be interested to see if we can find someone who can tell us how to wire in a pot which I don't believe is too hard.
The other one is ... from http://www.taskled.com/
They do a hipCC or a hipFlex and you can put a d2flex dimmable board with this. On the website there is lots of technical information and some downloadable datasheets.

I'm watching with interest ...

 

[Jonster]

I would suggest wiring the MCe's in series then the boards in parallel if you can. Much easier to find a driver.

Then you have the maxflex from taskled that will run them at 600ma per die at the highest setting

HTH

Zen - Given the same cost of maxFlex and hipFlex would you still recommend the former with the MC-E's in series and boards in parallel? is there any difference in efficiency?

 

[Jonster]

Sorry me again ... :ironic:

Here's another option on DX without the 5-mode ...
http://www.dealextreme.com/details.dx/sku.20330

I've also seen a buck-boost IC but not found a board that its used in ...
http://www.linear.com/pc/viewCategory.jsp?navId=H0,C1,C1003,C1094,C1769

 

[videoman]

Dimming is an absolute must. I have searched the web for over 2 weeks now and cannot come up with a boost driver say from 6 to 9 volts and boost it to 14.4 V and rated at 6A or more with dimming capability. I am building 2 models of video on-camera lights. One model is already designed using a buck driver from 14.4 volts power supply driving 3 MCE's in parallel die config, and all three in series with one shark buck 3A with external 20k log, pot. and the other video light must have 2 MCE's driven by a 7.2 (rated) 6000ma li-ion that is mounted behind the light to power it. That battery sometimes is 9V when fully charged and can go down to 6V at the low end. It must have dimming also. If I use a buck driver 3A with dimmer, that means that the leds must have a fV of 3,6V which necessitated parallel die config, and each die will get max current of 350ma (2 leds in parallel)which is far short of 700ma that I want.I could use 2 of the same drivers each driving one led thereby having full 700ma. on each die, a stereo pot will handle the dimming part. There are millions of buck and boost drivers out there but the one I need I cannot find.It doesn't have to be the nickel size one for flashlights but it must fit within a space of 3 inches long X 1 inchX1 inch.

 

[jar3ds]

why not use the CCHIPO?

http://www.taskled.com/cchipo.html

 

[H20doctor]

Why not use a Luxdrive driver with an input up to 32 volts.. At 1 amp . I run 3 MCE in series , all dimmable on 1 luxdrive.. www.ledsupply.com

 

[videoman]

I was looking at the CCHIPO and there's only one problem; it is too big to fit in the available space of 4 inchesX1inch X1inch. Thanks anyway

 

[videoman]

To H2ODoctor, which model of Luxdrive are you using and what is your input voltage ? My input voltage is between 6 to 9 volts and I want to drive each die at 700ma. I can't seem to figure it out. Also them size restrictions.

 

[jar3ds]

heh... for issues involved around this thread... i actually try to build flashlights around (in order)

1) electronics
2) batteries
3) the rest...