Cheap greenie issue is called resistance.

Hi there, I finally disassembled my Firedragon to get an access to the driver. And do you know what I've found? That the switch-spring-tailcap resistance is measured in full Ohms! Whole thousands of miliohms.. This is just enormous voltage sag created by all these crappy things inside of the laser's host. There is 2A tailcap-measured current draw from the fresh 18650 cell. Not good when there is so high resistance of current conducting parts. Now I'm considering how to take the photos of my measurements becouse I have no third hand to do this on my own.

My DMM is not very accurate becouse it has only 0.1ohm resolution. It shows 0.3ohm resistance when the wires are shorted. Tailcap alone shows 0.6ohm when shorted. Readout for spring only is 0.5ohm. And now it's time for the switch. DMM shows 1.0-1.6ohm! It's not anyone fault here. It's just a time for some kind of electrical performance tuning of my laser.

So the conclusion is obvious - if you have a problem with your greenie, for example low power, mode hopping, highly unstable operation, just think about the fact, that it can lose more than 2V of your cell's voltage..

Ohmmeters are bad at measuring resistances that low, like you said. Try it instead by sending a known current through it (1A with lm317 driver for example) and measuring the voltage across it.

You are right, but the problem is that now I have no equipment, even LM317 current source. So far I bypassed spring and the switch and cleaned key lock in the tailcap, now it is also "0.3ohm" readout everywhere. I must turn it on with a key it is impractical and I must find good switch as a replacement. I will see if even depleted cell can supply enough power to feed DPSS with full power.

I'm observing how fast can unfocused beam burn through CD-case becouse I have no LPM.. When cell had 3.8V or less it can't even burn through. With fresh battery it burned through in a 7-8 seconds. Laser is always turned on in a room temperature after cooling down. This is poor method but works. You see, lack of equipment is very annoying and uncomfortable. :cryyy:

EDIT, now it burns through CD case with the same speed not only with fresh battery but with 3,8V OCV as well.

i will agree that these aren't put together very well. the main problems i've had with mine are optical alignment. i've had to move the expanding lens and adjust focus afterwards to get optimum power.

i'm polish too, 2nd gen. jak sie masz?

Dzięki, w porządku Nice to meet you. Expanding lens in my laser is off-center, it should be carefully aligned by rotating threaded mount to obtain straight emission. What is more, focusing lens obstructs the beam even when all lenses are aligned properly. It has 5mm diameter and 20mm focal length. I've ordered few high quality AR coated surplus lenses and I'm going to fix all problems of my Firedragon. It will never be like an RPL but it is not bad after few tweaks.