Ultimate Night Vision Headlamp - 500+ lumens with only 8 watts

Step 11 Make the battery pack

the "Buckpuck" lets you use pretty much any battery pack. The buckpuck is just an efficient (90-95%) DC-to-DC step-down converter, so it will always output the correct voltage and current to the LED's no matter what the input voltage is. The LED's may need up to about 7V to run them, and you need to add 2V overhead for the Buckpuck - so any battery pack above 9V will work. 8 x NiMH cells will be 9.6V, 3 x lithium-ion cells will be 11.1V, and 10 x NiMH cells will be 12.0V. those are all good choices.

I used 8 x NiMH cells, AA size. These are 2700mAh cells, which yielded about 3 hours runtime at maximum power, and 24 hours runtime at minimum (1/8) power.

Comments

[mrsayao]

Hi Dan, I have a crap load of 9V batteries at my disposal. They're duracell alkaline... will they work? Would I be able to use 2 of the batteries to account for the overhead, since the buckpuck is regulating the voltage to the LEDS? Also, will I burn out the main big switch since it's rated at 14v? Great work!!

[karlosantana]

And if you want a REALLY kick butt battery pack go on ebay and search for Li-Po. It stands for lithium Polymer. It is one of the best battery packs I've ever used! Oh and cheers for this Instructable its awesome I've done three headlamps now one in red for hunting which works really well. Thanks again Dan Kyle

[Kasaron]

Don't LiPo's Explode when Overcharged?

[karlosantana]

Any battery will explode when it's overcharged but you have to buy a special charger for LiPo's that cut off when the battery is full, :D

[jumpfroggy]

Where'd you find a li-po charger?  Thanks.

[thinkdunson]

 i got mine from www.towerhobbies.com, but i'm sure there are hundreds of places.

[WestCoast]

I'm quite intrigued by this light and I'm getting ready to start gathering the supplies.  I was wondering if any one knows if I can I run more that 4 LED's with this setup.  Say maybe 8 for around 1000 lumens?

[pringelsfan007]

One thing to remember with a voltage limiter circuit, the higher the overvoltage the more heat and wasted power one will observe. As mentioned a two to three volt overvoltage is all that is needed to get the DC - DC converter to work properly. Any more cells in the battery pack than is needed is a waste of weight and space. Cheers! ;-)

[shepco]

Thank you pringelsfan007, I was wondering if Two packs of 8 AA should be run in series (24v) or parallel (12v).

[burna10]

Great project. I'm going to build one with the view of turning it into a dive light. The driving voltage has got me a bit stumped tho'. These 1 W luxeons, they have a driving voltage of 3-3.27 volts don't they? That would mean you'd need 12-13.08 volts to run them. Or have I got this arsed up somewhere?

[burna10]

Ahhhh, penny has dropped! You're running parallel pairs!

[fjguilfoyle]

HI there, Where did you get the pack that links all your batteries together? Thanks john

[dan]

digikey. you can probably find it at radio shack too.

[daniel333]

How do you recharge the batteries? Do you have to take all the batteries out and recharge them separately? thanks, Daniel

[dan]

yeah, i take them out and charge individually