Mini ML-X on 3.7 volt rechargables

It is my understanding that many people use 3.7 volt RCR123A batteries successfully in their Quark Mini ML-X's. Will a user still be able to access all three light levels when using these batteries or will it only run on high at that point? Will those lower levels be proportionally brighter than with a standard disposable 123A battery? It would seem like the brightness would be a max of 3.7V/3.0V=1.23 or 23% brighter than with a three volt battery (on all modes) but I've seen some claims that would make it appear to be far more significant than that. Is that true and, if so, is that because it is not regulated at the higher voltage?

Yes, you will be able to access the lower output modes on your Quark Mini X even when using RCR123A.

Yes, you will be able to notice the difference in outputs between primary and rechargeable. Allegedly, Mini X will put out between 400 to 500 lumens when running on RCR123A.

Yeah, you can't assume 23% brighter from battery voltage, it doesn't work like that (btw, a 3.7v battery runs about 4.2v hot off the charger) The mini-x will put out a huge amount of light, but it will also get very hot, very quick. It will also void any warranty, and possibly kill the light. There is also the possibility of killing the battery. I run mine with an IMR, but still only in very short bursts (no more than a minute) as it gets hot, and I get scared.

If you want small and bright and cheap, this is a good choice, but it carries a few risks. Make sure you know the risks before trying. We don't like hearing "My light died from over voltage cells" or worse still "I got injured from a venting cell in a small light"

Safety first

FloridaGuy said:

I3.7V/3.0V=1.23 or 23% brighter than with a three volt battery (on all modes) but I've seen some claims that would make it appear to be far more significant than that. Is that true and, if so, is that because it is not regulated at the higher voltage?

Click to expand...

The Minis work by 'pulse-width modulation.' They all (3.0v 123 or 1.5v AA using) have the same boost/PWM circuit, where one chunk of widgets steps up the battery voltage to drive the LED at some current, and another madly flicks the power on/off so that it looks dimmer on low modes. If you give more-than-enough voltage, the step-up circuit can't perform its intended function. A small part in it (Inductor coil) serves as a resistor to slightly decrease current from direct-drive levels. This can heat the inductor and destroy it, killing your light.

The LED's response to current is exponential, not linear. Supposing a Cree XP-G, the current can double between 3.0 and 3.6v. A fresh Li-Ion cell can be 4.2v, and drive the XP-G at truly unsafe currents. All that power goes somewhere, and only 1/3 of what goes into the LED comes out as light. The rest is heat, and heat can damage the LED, the circuit, and the battery. Damaging the circuit is boring; the light will stop working normally. Damaging the LED will dim it by VOC deposition or damage. Damaging the battery, though...that's what can hurt you. Be careful overdriving lights. Monitor heat, and don't loan it to someone who won't.

My experience on these circuits utilized by FourSevens, Olight and iTP, is that the lower two modes are the same brightness on a CR123 as on an RCR123. I believe however the high mode is not regulated and is direct drive so you will see a significant brightness increase and risk damaging the LED and/or circuit from heat.

Check out selfbuilt's review on the Olight i1 which is pretty much the same as your Mini-X except without the hidden blinky modes for exact light output figures.

http://www.candlepowerforums.com/vb/showthread.php?326146

The XML is great on these minis at quickly draining down the LiCo RCR123 to a point the heat is less of an issue. Read post 15 from the above mentioned thread for more info.

Obviously RCR123's are still officially frowned upon by Foursevens, but it's a managed risk that is worth it to me in the long run despite loosing the warranty.

I just bought another Gen 2 light because I LOVE the one I have now. I was surprised to notice that the literature says "no RCR123's". I only use mine for about 3 minutes at a time. However, I loaned mine to a friend, who forgot to turn it off after using it. When I noticed that she had left it on, I thought it was kind of funny, so I did not mention it. She walked around for ~10 minutes with it hanging from her neck before someone else mentioned that the light was on. Maybe she didn't have a problem because the battery had drained down. I don't know. I recharge my batteries after every evening's use. I trust this light with RCR's and use nothing else. I'm definitely not an expert, just a user. Never had a problem accessing all three levels.