Re: Ok, regulated is better, but how about resisto
I have been down both paths with this with $ spent on each method, so here is MHO and what I am doing for my upcoming small light.
I personally like the 2x123 format, good power capacity, flat voltage curves over a broad demand, small, etc. These also have the real advantage of being able to drive a light under adverse weather conditions.
In my particular light, I am using a 223 battery (breaking the rules, of course), but this is a 2x123 setup prebuilt in series, with both terminals on the same end - this was a particular advantage for my setup.
As far as regulated vs resistored - In order for most of the regulated setups to work in a buck (down convert) mode, the electronics need Vin at least 1 V above Vf. If you have a Lux III with a Vf of 3.5V, add a protection diode (0.3V), you are fast approaching 4 volts.
If you then look at the energizer curves, and try to draw 500ma + from them, the voltage delivered will rapidly sink to only 0.5 V or less of headroom. This is getting pretty tight. A cold battery might not do it.
For my light, partially due to space constraints, I used a 2 ohm, 1206 size resistor for high, 10 ohm for medium, and 200 ohm for low. Since there is already 0.5 - 1 ohm due to springs, contacts, etc, this puts the actualy current (at least in theory) around 750ma, 300ma, and 30ma respectively.
My worst case condition for power dissipation is somewhere around 1 amp (at the very start of the cell life), so 1amp x 2 ohm = 2 watts in the resistor, and 3 watts in the Luxeon III. This ratio actually improves within 1 minute as the voltage stabilizes closer to 5.3 volts (at least on the charts)
The real problem I had with the design was that all of the small resistors I found were only 1/4 watt or less. I ended up, much to my dismay, having to have a batch of custom resistors made up for the ohm range I wanted. The price per resistor was not that bad (a few $), but the min order was 250 for each resistance, so it added up.
I now have a lot of these resistors either already or almost due. I do not need all of them, so if anyone else needs some 1206 size 2, 10, 25, 30 ohm, 50 watt (yes, that is a fifty watt) resistors, PM me.
I probably will put them up in the shoppe so I don t have to deal with logistics.
I think that if you have a 2x123 format, and unless you get regulator electronics that can handle both buck and boost, resistor is not that bad.
Pulling more than an amp out of a 123 IMHO is not ideal.
HarryN