Which driver for this set-up??

Hi there,

Here is a fairly simple headlight set-up (one would have thought) - I want to run a cree X-RE LED off three 2600mAh NiMh batteries and acheive the brightest light I can for 2 - 2 & 1/2 hrs.
I am trying to understand the difference between running it directly off these batteries, and incorporating a driver.

For direct drive I am assuming the foward voltage of the LED at around 3.7v is good to go for the batteries 3.6v. What are the down sides? How long would you expect it to put out a decent amount of light?

If I do go down the path of using a driver, should I use a boost or a buck or other?? I have looked at some of the Taskled & LuxDrive ones but I am unsure of what I am looking at ... enter you guys.


Am I better using:

• a 3021 BuckPuck drives Cree XR-E
• or a Taskled CC5W-700/350/80
• or a luxdrive micropuck 3V 1W, 500mA 2009A-SHO
• or other??

Lastly, with a driver is it as simple as dividing the battery mAh by the current rating of the driver to get the run time? I.e if the driver was 1000mAh and the batteries were as above, it would be 2600/1000 = 2.6hrs of run time (approx)??

Please help me with what I would have expected to be a relatively easy question for you gurus :twothumbs.

Cheers
Daza

Your calculations for run-time vs. battery capacity are OK.

I approached your requirement for a headlight in a slightly different manner. Rather than starting from scratch with an LED, driver board, reflector, housing, etc. I selected a flashlight that runs on a single 18650 (or RCR123A) with an operating voltage range of 3.0-4.2V or so. I then connected it to a 3x AA NiMH 2600mAH battery pack.



The particular light I selected is about $11 and puts out 150 lumens at 830mA - slightly less than what you want. I used just the head and discarded the body and switch. This particular light has an XRE and a 5-mode driver (high, mid, low, strobe and SOS) but single mode ones abound. The head itself is 21mm x 38mm and weighs about 21gm. By the time you add the cost of the LED, driver board, reflector, housing, etc., this approach is a lot cheaper and much simpler. You should be able to find many lights that put out 200-250 lumens (Q5 or R2) for $20 or less that draw about 1000mA from the battery.

Hey there, cheers for quick reply. Your set-up looks almost identical to the one I am running at the moment. I too disected an existing flashligt and utilised the same size section - I am even using the exact same triple AA pack! My setup is running with no driver i.e batteries direct to LED (X-RE).

How come you didn't direct drive yours?
What is the driver you are using?

Cheers
Daza

A driver will give much better regulation plus it gives multi-mode operation which I want. The light came with a driver.

rmteo said:

The particular light I selected is about $11 and puts out 150 lumens at 830mA.

Click to expand...

Hi rmteo, what is the light that you selected?

Cheers
Daza