Sorry fellows but, after observing lots of li-ion cell discharge curves:
When a cell is fully or nearly fully charged and/or nearly discharged the discharge curve slope is higher. Measuring internal resistance when cells are close to full or empty is just wrong.
When a cell is discharged it heats up proportionally to the square of the current flow. This usually means the cell's internal resistance diminishes a little bit.
In every other aspect, li-ion cells' internal resistance is fairly constant.
I think that however you decide to test, the key is to be consistent and measure all your cells at the same charge/voltage level so that you have apples to apples comparison.
I would say it’s best to measure Ri at the average Voltage, which is 3.7 Volts (without load).
This is in the middle of the range the battery is used in most of the times.
Well, since this thread is more or less about the OTR M3, which (probably) has a linear CC driver with maximum current of 2.3 Amperes on ‘turbo’, it should actually first be established how much voltage it needs to push 2.3 Amperes through the XM-L2.
I’m not even sure how much voltage this particular generation of XM-L2 needs to draw 2.3 Amperes.
what are the lumen levels and mode sequence of each light:
Jaxmnve M3
OTR M3
Do both lights have built in over discharge protection, (which means you do not need to use protected cells)
Does anyone have beam shots comparing the Cool White and Neutral white?
Since both are low CRI, the choice of Color temperature should be based on whether you plan to use the light when your brain is white balanced to a Cool White environment, or a Neutral white environment.
Neutral white that is Low CRI does NOT improve Color Rendering, because it outputs more Yellow and less Blue than cool white. However Neutral White Low CRI does NOT produce more Red.
since the OP is talking about wanting the most brightness, Imo he should buy Cool White… (Im not sure which one he ordered after all)
I am very happy with my Keepower IMR Unprotected cells.
But the discharge rate of the cell may not matter IF the M3 modes are Regulated… Are they?
however, I do not have any Neutral White Low CRI lights myself, so I cannot compare a 5C XM-L2 to a 4000k N219b myself. If you have both, maybe try taking some photos of your hand with them. Try to use daylight white balance for both photos.
here is another example
natural daylight:
Low CRI:
High CRI:
In any case, High CRI is not an option with the M3, you can only choose the color temperature, Cool white or Neutral white
I personally avoid Cool White unless I am using the light during daylight hours, when my brain is white balanced to daylight. But I mostly use my flashlights after dark, so Cool white is not my preference…
each person has different needs… because they use their lights in different ambient light scenarios
my solution is to buy some of each kind and swap lights depending on the environment…
I think you are right, neutral white low cri does look like it has better red than cool white low cri, not as good as neutral white high CRI, but definitely better than cool white
Cool White:
Neutral White:
the red does look less brown with neutral white, even low CRI, the other colors also look more realistic to me with the Neutral than with the Cool
thanks for helping me learn to be more open minded
since Im a color snob, I agree with you that the two choices of LED for the M3, I would pick the 5C Color Temperature.
Same here, but to me, the light has to be brighter. Cooler CTs are more jarring to the eyes, so even a little light has its own shock-value, but warmer CTs are smoother and less of an assault on the senses, so I kinda “need” more of it.
also agree, as lights go up in CRI, they also tend to go down in brightness
as lights go down in Color Temperature, even if they don’t go up in CRI, they also tend to go down in brightness
That’s probably your perception or just your preference.
Low CRI LEDs simply lack deep red, even rosy tinted warm white ones.
And especially with warm white LEDs i really miss the deep red that you would expect from a warm white light source.
With cool / neutral white low CRI LEDs (like Cree 3A tint) i don’t really miss the deeper red too much.
But this is perhaps my perception or preference.
This is apparently around 3.3 Volts, according to TA’s testing.
No wonder the current drops when my PKcell is discharged below 3.6 Volts (without load).
My OTR M3, Cree XM-L2 U2 5C, pulls 1.32A on high, 2.35A on turbo from the original fairly well used OTR cell. Fully charged but rested 24hours. Turbo is a lot brighter than high. The 5C tint is pleasing to my eyes.
That’s just using a ordinary DMM on 10A scale with standard long-ish 18AWG leads. Measurements made after several seconds, to steady.
I have found the original OTR cell to be very good indeed, as is the torch. Interested to know of any alternatives that can genuinely match e.g. 2.35A on turbo.
I have an X5 on the way to me, with the same LED. Will be interesting to see how that performs, with supplied OTR 26650 cell, not really expecting much more.
Sorry for this noob question. Can I please ask how you guys are measuring the current draw of the battery on the OTR M3? I have a very old (about 20yo?) Tektronix Multimeter (model: DMM157) and I can’t seem to get a current reading with the probes over the negative terminal of the battery and trying to ground the other probe on the thread with the tailcap removed. I read on another blog that it is because most flashlights are anodized. I can’t seem to find any other exposed metal on the flashlight body to ground the other probe to?
The multimeter does work, as I tried the same method on my Zanflare F1 with the tailcap removed. However there is no tail switch on the M3, so perhaps I need to use a different method to get the current reading??
That’s pretty much how I did it. Touch one probe to the negative battery terminal, and touch the other probe to the top-most/bare part of the thread. While holding both probes in place, you then need to turn on the flashlight using the side button, which can be tricky - you may need another person to help you.
Thanks for this. I didn’t have enough fingers/hands to turn on the side switch myself. Just got another hand to help turn it on. With the battery on 3.62V, turbo was drawing about 1.7A. Will put the batteries on the charger to charge to FULL, and will test again tomorrow.
