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Yes I do :thumbsup:





It was sort of put on the backburner with the liberator going mad over here and only 7 were made as protoes .
now there has been so many enquiries for a small helmet light with a big heart that I have just put in an order with my CNC man to make a batch of housings and mounts .

I have been using a Bflex in them and a 4s LI Ion pack but the new lot will have a tab for a maxflex included so a smaller 2s li ion pack can be used this makes it doable for the battery to be on the back of the helmet .

Lumens well going off the measurements form over on CPF then with 4 xpg in it will max out at 1400 lumens @ 1000 ma drive current .
and around 1000 lumens with XPEs on board

a few more pics and beamshots HERE

Current draw running at the 1000 ma Bflex current table is High .940 ma and low .120 ma
from a 15 volt source.

So it is looking like a couple of weeks before the housings are made

I do have 1 of the protos left I was in the process of building it up but needed to steal the leds out of it

 

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Discussion Starter · #3 ·
I've looked at the taskled website and I can't figure out what difference the bflex and maxflex driver would make in using the 14.8v pack or a 7.4v pack?? The site says they both accept about the same input voltage. Wouldn't everyone want to use the 7.4v if possible to keep battery weight/size down? I'm sure there's something about the drivers that I completely missed or just plain don't understand!!
 

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Yip there is!

A maxflex is a boost driver. That means that the input voltage from the battery must be lower than the voltage needed to power the leds. For instance, an LED has a Vf for about 3.3v. So 4 leds will need 3.3 x 4 = 13.2v. Now you can plug in your 7.4v battery and power the 13.2v light. The 14.8v pack will simply cause the driver to 'direct drive'. ie. no regulation of the current.

But you can however use the bflex with the 14.8v pack as it is a buck driver. Buck drivers require the battery voltage to be higher than the vf of the leds.

So there you go!
 

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Discussion Starter · #6 ·
So...... will there be any big disadvantages of running a 7.4v pack instead of a 14.8v?? I'm not the most techincally advanced person out there if you can't tell! The way I have it figured a 5.2ah battery pack will last the same amount of time no matter what the voltage??
 

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The maxflex will draw more current out of a 7.4 compared to a 14.8. The light still requires the same amount of power to light up at say 1000mA.
So it will draw twice the amount of power from the 7.4 than it will from the 14.8
Have a play around with this http://www.kenworster.com/ledcalc/

As to the runtime, I cant help you there! Maybe some one with a bit more noggin will help out!
The calc says it will be the same, but from experience, my lights give me a whole lot less riding time with a smaller voltage battery!
 

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Got it!
You need to work out the led watts. Multiply the voltage and the Amps.
13.2 x 1000ma = 13.2W

Then mulitply the battery voltage and the Ah to get battery watt.hrs
7.4 x 5.2 = 38.48Wh

Now divide Wh by W and you get left with hours.
38.48 / 13.2 = 2.92hrs.

With your 14.8v battery you get 5.83hrs.
Your driver will chew some of that power so your runtime may be less.
 

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bncrshr77 said:
Hmmm, I follow the math you did for sure.....But, why would the CALC tell me the run times are the same?? By the way, thanks for the great replies!!
A 5.2 Ah battery at 7.4 volts would be 4 x 3.7V 2600 mAh batteries wired 2S/2P.
A 5.2 Ah battery at 14.8 volts would be 8 x 3.7V 2600 mAh batteries, wired 4S/2P.

So you have twice as many cells with a 14.8V 5.2Ah battery as you do with a 7.4V 5.2Ah battery.
 

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The boost driver should waste more power than the other driver so I'd expect the 7.4V setup to last abit less than 1/2 of the run time of the other 1.

I want this light myself but can't afford at the moment :(
 

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rob hughes said:
troutie.is there a wee gold one somewhere in there for me..please.sir.master..
Yep Rob
will get a few done in gold :thumbsup:

Yes Tom .
I have been running the first proto on a headband for dog walking duties with XPEs at the full 1000ma drive with no issues apart form dazzling the pooch .

am also using a 14.8 volt li ion and the bflex with no worries and if your batteries are the 5.2 amp hour plenty of burn time for a good ride
I find the bflex stays in regulation for a good % of time even with a 2.6 amp hr.

and I have just checked 6 xpgs and they all had a vf of 3.2 v @ 1000ma so bringing 4 in at under 13 volts
 
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