Olight M2X-UT Javelot (XM-L2 dedome, 1x18650/2xCR123A) Review: BEAMSHOTS, RUNTIMES+

selfbuilt

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Could you post the M2X-UT runtime using the OEM battery extender (2x18650)? I have purchased 4 M2X-UT for my friends all with the battery extender. Just curious if the runtime curve is comparable to M3X-UT.
I did 2x16340 and 2x18350 runtimes in this review of the M2X-UT - and 2x18650 wouldn't look any different, except for the extended runtime.

I know it's a bit hard to see in the graphs in this review, but output of the 1x and 2x 3.7V Li-ion sources is exactly the same: the light starts out ~950 estimated ANSI FL-1 lumens, starts a controlled (timed) drop in output starting 3 mins, leveling off at ~650 lumens after ~5.5 mins. It then stays regulated at this new lower level. The only different 2x18650 will make is extended runtime at this lower regulated level.

It's a different circuit form the M3XS-UT, but the M2X-UT handles all voltage sources exactly the same way.
 

EasyB

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I don't think this has been mentioned; an important advantage of using 2x18650 is that even at a low state of charge, the flashlight should output full brightness on high. For example, if a single 18650 cell is at, say, 25% state of charge, the light would not be able to output the full 950 lumens because the battery voltage would most likely be below the LED forward voltage for this output. But with 2x18650 in series, each at 25% SOC, the voltage would still be above the LED forward voltage and should output the full 950 lumens. This advantage is not apparent from the runtime graphs because of the timed output drop.
 

EasyB

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I am thinking of buying this light with the extension tube so I have the option of using 1 or 2 18650 cells. I am wondering about the low battery warning/protection. With 1 cell, you get an indication that the charge is low when max mode is not much brighter than the next mode down. This is how I tell the battery needs recharging in my fenix TK15 (337 lumen version), and I imagine lots of similar lights with just buck regulators work in a similar fashion. But with 2 cells, from your runtime graph, it looks like the output drops unexpectedly, and by this time, the cells are probably depleted to under 2V per cell.

I have lights where there is no low battery warning, and you just have to be vigilant and be aware of the battery voltage to make sure it doesn't get overdischarged. It sure is nice to have a low battery warning, though. Like on my Nitecore HC50 headlamp; it is designed for 1 18650 cell and it tells you when the open circuit voltage is below 3.6V (roughly 50% discharged), and it also has a built in volt meter.

So, for this M2X-UT, is there any warning system, or do you just have to be aware of your battery state?
 

selfbuilt

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But with 2 cells, from your runtime graph, it looks like the output drops unexpectedly, and by this time, the cells are probably depleted to under 2V per cell.
No, what you are seeing is the battery protection circuit kicking in. The resting voltage would be higher. There is no low-voltage warning feature on the light that I am aware of. You would need to monitor the status of your batteries if you want to avoid being potentially surprised.

It is rare to see low-voltage warning features on multi-cell lights - unless they are intending for you to use unprotected cells (which is not the case here).
 

Brightpreme

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First of all I was very impressed at ththe detail of your review. I own a first run m2x with the dedomed XM-L2 emitter and boy does it throw. For a stock x1 18650 light of this compact configuration it's performance is top notch. I always get a lil giddy whenever I shine it outside at night and witness its upwards of a half mile beam.
 
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