1/2 aa Small Flashlight Project: Driver/LED suggestions please!

Hello everyone!

I have just been given a load of small lithium batteries, they are all approximately 1/2 AA size, and give 3v, though some are a tiny bit bigger than 1/2 AA, same length but slightly bigger circumference (won't fit in a AA MAG tube) and supply 3.7v.

I am hoping to buy a lathe soon, one project will be to make cylindrical bodies that will fit these batteries and different LEDs.

My question is, what driver and LED would you recommend? I'd like to have a small, regulated light, with a smooth spot. It's mainly for use in my house, at night, checking on my kids after they have gone to sleep for instance, so low and high brightness levels would be a definite advantage. I want this light to be as small as possible and run off a single 3v or 3.7v battery if possible.

I have bought and dismantled an Inova 4-mode microlight, and despite the low voltage (these lights are designed to run on 6v, from two flat lithium 3v button batteries) the chip and LED work well. From the 3.7v batteries, the brightness is almost the same, while it is a little dimmer, but still adequate from the 3v batteries.

I was wondering what your suggestions would be (apart from the Inova!) for a regulated driver that would make the batteries last as long as possible while providing low and high modes, with a beam adequate for indoor use while being smooth enough for reading a book? A physically small driver that would fit in an AA size tube would be ideal, perhaps one of those 10mm LEDs that were mentioned on here by Milkyspit would be nice?

Any ideas or suggestions would be gratefully received!

Do you know what the batter chemistry is? If they are the 1/2 AA's that they use in many computer backup/sensor applications( similar to these http://www.saftbatteries.com/120-Te...techno=Lithium+systems&Intitule_Produit=LS,+T) then they sag ALOT under any significant load. I was just playing with some that sagged to 2.9V under a < 100ma load and they were new. Also, when I shorted them through my ammeter, they could only supply ~ 500 ma. You may want to test your batteries before you spend a bunch of time making bodies.

Thanks, but I don't think my batteries are the type you describe. I have been using one, daily, in a regulated nine-led flashlight in place of a CR123A (with the addition of a tube and a conductive spacer in the battery compartment) for almost a year now! There is a definite drop in brightness compared to when the flashlight has a CR123A installed, but it's still useable, perfectly adequate for what I want. It's just a pain to keep in a pocket full-time though, just too bulky. The endurance of these particular 1/2 AAs seems quite impressive.

I am sure that there are some of these batteries that aren't ideal for flashlight use, but these ones I have seem fine! I'd really like to try them with a small, regulated circuit, and for the application that I want, high brightness is not necessary, which is why I'd like to maybe buy a circuit with high and low levels.

I'd really like something small and neat but can't afford a CR2-ION at the moment!

Thanks for any help,

Rob M

The flupic can be made quite small and can run off of a 3v or 3.7v battery. I can dumb down the interface to just a basic low, medium, high or anything you desire. Thanks.