Noob Modding Questions

I'm new to flashlights in general, and even newer to modding. I've cut my teeth on a Romisen RC-G2, upgrading the LED to a P4 and switching out the driver board with a more efficient model. I find modding to be pretty fun, and I'd like to continue with some basic mods on other cheap DX lights to build my skills. I have a couple questions that the Search couldn't help me answer.

1. How can I measure/determine the efficiency of a driver board? I have a multimeter but not much else in the way of electronic tools. I figure there must be a way to estimate runtimes without turning on the light and running it down. But maybe not?

2. Possibly related to #1. People sometimes mention that their light "draws X amps." I assume this number relates to a light's brightness and runtime. What is significant about amperage draw, and how can I measure it?

3. I have a fondness for simplicity, but also versatility. Consequently I prefer lights that can fill multiple roles. Bright is great, but sometimes you need softer light for reading at night. Something I think would add versatility to my RC-G2 (or any cheap single-stage light) is a two-stage switch with tailcap resistor, like the LM31. Is this modification possible on most lights, or only on some? How would I accomplish such a mod? Links to guides or walkthroughs in this vein would be very helpful.

Thanks,
Tycho

Anyone?

I can give you a quick answer to #2.

If you remove the tailcap of a light, such as a Maglite, you can easily find the amps drawn from the cells.

Just set your DMM to amps, put one lead on the back of the battery, and the other on the rim of the flashlight body. With the light turned on, this should give you a reading of the amps being drawn.

This is not the same, however, as the amps being seen by the emitter in an LED light. It is simply the amps being pulled from the batteries.

schiesz

Thanks schiesz!

* in general, efficacy of drivers is between 80-85 % (with up to a bit over 90 for very good drivers)

* current draw at battery is the only way to

• check overall conditions
• measure how well the rechargeable cells are
• estimate runtime

* in general, a white led runs on 3.8 Volts,
thats three Ni-Mh cells, or one Li-Ion
without regard to the losses of the driver, the current drawn at a single Li-Ion cell = the current the led gets
its less, because of the losses, but just to have a rough guess

... now when the battery setup is not three Ni-Mhs or one Li-Ion, but say: 2 AA Ni-Mhs:
--> check current drawn at cells
--> battery voltage (number of batts) is just 2/3 of what is needed
--> get current value checked and multiply with 2, divide with 3
--> = current to the led
no maker has yet discovered the holy grail of power source and thus its very easy to say "this output/brightness is not possible for that runtime" when simply the number of cells and the current at the cells is given - and those are very easy to get infos.

* step-up circuit is harder on the cells and, in general again, has more losses

* 2-stage tailcap is one way, the better (imho) is to use a driver that can switch levels. A single stage switch is easier to operate and much more sturdy


This is just my actual opinion: I started with modding, like You do now. And still appreciate it, because there simply is nothing that can do what I want (which is 18650 multistage output with best beam possible (= Sandwich Shoppe reflector) in a tint I want + an "intelligent" driver (a Flupic here) ),
but when You really combine all the cost of the modded lights + parts and the work involved, one is almost in the price class of a Fenix which is better.
With Fenix entering the market, modding makes only sense any more, when one has special wants

Depending on the light, a 2-stage resitored tail can be easy, or impossible. Sometime (usually buck/boost) drivers don't like resitored tails, unless they are of low resistance, 5 ohms or less.

Some lights have switches that can be simply replaced by a Judco like this Lumapower D-mini mod, or this Sterops mod. Or the mod can be much more involved like implanting the Judco in a Kroll.