complete newbie trying to get my head around things

[stuj]

Hi all firstly i'd like to say hi and what a great and informative site, i've been lurking in the background for the last couple of weeks while i've been investigating making some lights.

i'm thinking of going for 3 ssc p4's in a custom housing using it as a heatsink as well.

The biggest thing thats stumbled me is driving it.... i really like the bflex and am on the verge of ordering but i am not sure if i would be able to do what i want. my other concern is creating a battery pack that can be integrated into the housing with the led's and driver i guess i'm hoping a bit too much maybe ?

i would imagine i need a boost controller for this to be realistic but are there any that have the awesome control of the bflex ? or should i just have a remote battery to do the job............

any ideas greatly appreciated

regards

Stuart

 

[StevelKnievel]

Taskled's MaxFlex is a boost driver with UIB, which has similar control to the UIB2 of bFlex. Should be close to what you want. What's your plan for fabricating a housing/heatsink?

 

[stuj]

thanks for the reply knievel.

i didn't realise the maxflex had the uib

housing will be machined out of aluminium and most likely anodised. once i have decided on controller i will choose battery and then draw something up on solidworks to get something in the region of how it wants to look and safely house everything. and be in a singular package and a connector for charging too.

is there any links for calculating the batteries i'd require for a boost circuit. i've done loads of searching but can't find anything maybe i'm being blind.

thanks again Stuart

 

[Light_Mule]

Coming from the bike world(20 years as a Mechanic) it would be best to keep the weight at a minimum on the handlebar say under 240 grams as that can adversly affect steering. Thats why you see so many bike lights with a separate battery pack that mounts on the frame. Hope that is helpful. What kind of specs are you looking to produce i.e. runtime and brightness?

Mule

 

[StevelKnievel]

Batteryspace has a fair selection of small, light Li-ion batterys that would work. 7.4V is perfect for boost driving 3SSCs. You should be able to get reasonable runtime with a battery like this:

http://www.batteryspace.com/index.asp?PageAction=VIEWPROD&ProdID=2439

I agree with Light_Mule, the real challenge is designing a housing that is compact, durable, and light enough to be used on the h-bar (at least for mtn biking). Solidworks is a great design tool because you can calculate the mass of the object you have modeled. If you use the battery I linked to above and get the mass of the housing down to around 100g you'll end up with a light that is around 300-350g. 100g isn't a whole lot of aluminum considering you are trying to house the battery and integrate sufficient heatsinking into the assembly. I'd love to see it done, though!

 

[iggs]

If your starting from scratch and have no existing batteries to use I'd consider building/buying a 14.4volt battery pack. I'm basing this info on stuff I've read on here and on the taskled.com forum about how much better stepping down is rather than boosting up. This appears to be in terms of efficency and how it reduces the risk of damage to batteries.

have a look here for instance http://candlepowerforums.com/vb/showthread.php?t=176696

I'm going to use the maxflex because I already have 2 x 6volt 3000mAh batteries and a charger.

 

[stuj]

thanks for the input guys.

ideally i would like to be able to run the lights at max for say at most 2-3 hours but be able to use the lower settings obviously for longer.

i understand what your saying about the weight but i did want to build a smallish light anyways with the possibility to plugging into the back with an external battery pack if i needed to.

maybe my mind will change if i can find a sufficient li-ion battery pack that is small enough with suitable V and I capabilities to use a step down..........

my search continues

one last question if i were to step down on 3 leds what could be the lowest V the battery could drop to before losing light ?

thanks

Stuart

 

[iggs]

My understanding is that when the voltage from the batteries drops to the Vf of the LED's then it just goes straight through, i.e. control of the board is lost and the LED's will just slowly dim

 

[znomit]

You add the led voltages and then another volt for the bflex driver.
This is the minimum voltage, so at full charge you want to be above that.

3.7x3 + 1 so you need over 12v to maintain the high current.

Im a big fan of NiMH AAs...you can build the battery pack to suit your needs and can source standard AAs if you are on the road for a few days.

one last question if i were to step down on 3 leds what could be the lowest V the battery could drop to before losing light ?

 

[stuj]

ok well i've bought a couple of bflex drivers now it's the choice of which seoul emmitters to get uswoh usxoh ????? i have read the data sheet but still not sure which are the most suited ?

cheers Stuart