Generally, to get an estimate of lumens based on the draw in comparison to the led specs.
2 cells in series * 1.5v = 3.0v * 300mA ~ 0.9W if my math is correct.
Since you were using the batts that came with the light, I assumed alkys at spec volts.
NIMHs have lower voltage, but I suspect they could have a higher draw, but how much depends on resistance (usually lower than alkys) with a direct drive . . this is why I posted in the build thread it would be nice to see the actual numbers as a reference point.
Well, if I knew enough, I might do that. Anyhow, the NiMHs had a lower draw. I only read 100ma to 150ma at the tail with two fresh NiMHs, but I figure it’s because of the lower voltage of NiMHs vs Alkalines. I took it for granted that fresh Alkalines would give off 1.5v each.
I only have one ammeter and it is the old style analog. I bought it because I can read an analog, but I can't read that digital crap. Every time I used the digital meter I had, it would jump all over the place and I can take the analog meter and it reads solid as a rock, so I just (today) ordered an analog voltmeter. Maybe I will be able to read voltages that way. I never could do numbers all my life (dyslexia they say now, stupid back then), but I can read an analog meter needle.
The forward voltage of an LED will go up with the current. While some LEDs barely light up at 2.5V, they can be mind-blowing at 3.2V. There are some tables, but they arent really reliable.
For example, the current in relation to the forward voltage of an XML:
Voltage determines current. Thats why we use linear regulators, they limit the current to a certain value and adapt the forward voltage to that level.
So, while 2 Eneloops (2.6V) can deliver way more current than 2 Alkalines (3V), the light will be brighter on Alkalines. At 2.6V, the XML maybe can pull 100mA while at 3V it could pull up to 1A.
I hope that helps.
@OL: If you want to build brighter lights that can be used with 2 AA cells, get this driver:
I’ll take some readings and lux measurements when I receive it.
I’ll take readings for 2 alkalines @ 3v, 2 NiMHs @ 2.4v, 1 14500 @ 3.4v. Hopefully then we can learn more about the 219’s current/voltage relationship.
To get half the brightness of Slewflashes 200 lumens only requires 50 lm.
With the specs given, one might get ~60 lm OTF (based on around 90 lm from the LED) from fresh 1.6V Alkis: with voltage & output dropping over time. NiMHs might give a constant 30 lm for 12 hours at 150mA.
It could be considered as a superior, lightweight custom built Dolphin, giving over a 6 hour runtime from 2AAs.
If Slewflash found it unsuitable for the parents I would be happy to repurchase it for $35 - just no Li used, not even 1.8V AAs
The Nichia spec sheet found at the IS link above shows a different curve shape (& weird scaling), but with the same principle.
It also seems to show l-ion voltages of 4.x as workable (if I’m reading pg. 11 correctly - so due diligence is urged) with more than 4x the lumen output at full charge vs the 350mA standard cited above. However, the duty ratio (pg. 9) is much lower at the high draw.
After I’m done testing, I’ll let my dad play around with it for a few nights and if it’s a bit too dim then I’ll be happy to sell it to you.
However, I will be testing Lions @ 3.4volts (for roughly 2 minutes just to get lux numbers), if that’s okay with you. For normal use I’ll be using 1.2v turnigy AAs.
Maybe a lithium primary(3.6 new, 3.3 nominal). Sold in AA size might be just the ticket. A good idea maybe for a gift light.
Obviously not stupid, but different. I’ve come to the conclusion that all that convoluted grey matter upstairs really does make each of us think and figure things out differently. One size explanation does not fit all. Justin, you are gifted with an extraordinary eye, patience, and skilled hands to match(or a really large garbage can). With things like dyslexia it takes a different approach to convey information. Maybe a YouTube video would help. Or a beer and less chatter.
If my old memory serves, a fair percentage of the population are dyslexic, including some very intelligent ones (check WikiP or Google: Einstein & da Vinci may be mentioned) - the point of differentiation for we third chimps; the so called common chimp being physically stronger, & the rare Bonobo more emotionally advanced.
I just received the light today. And I can definitely say that I am IMPRESSED! Thank you Justin
After I discharge a 14500 down to 3.4V I’ll test it out the lux readings and ceiling bounce with 2AAs (3.0V), and then with the 3.4V 14500. I have to say though Justin, this will make a REALLY nice gift. Your work is amazing and I thank you for it
Even the packaging of the light was really well done too.
I’m looking forward to your other builds Justin. Hopefully a direct drive SST-90
EDIT: And I thought my IO p60 drop in NW module was awesome at rendering colours. This thing… really is so great. Now when I look at my CW lights everything just looks so garish and unattractive.
EDIT2: Actually on second thoughts I won’t be using the 14500 at all. It cuts off at 3.2V so it’s pretty pointless.
EDIT3: I think I may have worked out the lumen output, it’s very rough though.
This is based on the assumption that my SR King puts out 2300 lumens at 5 seconds after I turn it on.
So I ceiling bounced the SR King, and took the number down after 5 seconds. Then I did the same for the maglite. And yes, I did put them in the exact same position and I didn’t move the meter. Used the same method for both lights. and did it three times.
I divided the SR King’s number by the maglite’s number to get the factor. Then I divided 2300 by the factor and averaged out all my results. I got 99.71 lumens(but this is all very rough anyway, so I reckon the margin of error is probably plus or minus 15%).
Also at 1 meter I got 8k lux, which is pretty good I’d say It is definitely brighter than those 5*5mm LED flashlights you see in australian supermarkets. I think I just found my new house navigation light
High CRI really makes a difference. If you have a chance to use it to light up a large photo, poster, or map, you will see the colors so much more realistic.
If I were you, I would try the 14500 withought bleeding it off. What are you talking about 4.2v? or higher than that? 4.2 shouldn't kill the led, since it's going to sag right away. I've done 3 AA Alkalines with these Nichias and that's 4.5v when it turns on.
Okay, I’ll try the 14500. I’ll take the readings now. Fingers crossed! BTW I edited my last post to put up rough numbers of the lumen output. And it has 8k lux at 1 meter.
EDIT: Looks like I’ll have to wait a short bit, my highest 14500 goes to 4.13V. I’ll charge it up to 4.2V then I’ll test it. And the alkalines I used in the first test read 1.57V after I finished testing.
Okay, after some confusing results here are the final numbers:
3.14V (2AA alkalines): 99.7 lumens, 800 lux (I accidentally misstated the previous readings, it’s 800, not 8000).
4.23V (1 14500, 1 dummy): 288.3 lumens, 3,400 lux.
Again, give it 15% leeway for error as these are just rough numbers, but it’s interesting to see how much the output increases with just an extra 1.1V. Amazing!
I am pleased for you (kudos to Justin too) & just a little sad for me
From your earlier post (#8) aren’t you quoting LED lumens - OTF might be 2/3?
Cheers, John
EDIT: From another thread I have just bought some safer LiFe 3.2V AA & AAA cells, plus a charger. $23 for a 3.6V (rather than 4.2V) charger plus 4 batteries might allow your dad to more safely operate this torch - with an LED lumen output closer to 200 lm giving a cooler & longer runtime? Although AA capacity is only 600mAh.
I kind of want another one or two, and maybe to give away to someone who appreciates high CRI lights, but maybe it’d be better off to left the next person to get it. But if Justin is up to making more than one then I would be happy to get another one
From post #8, it says this: B10 Flux Bin(100-110lm@350mA, 2.7-3.1V)
And with my crude method I measured 99.7 lumens at 3.14V, 300mA. I’d say that it’s pretty accurate. This test was using 2 AA alkalines. Btw it’s worth noting that in the first 20 seconds, on alkalines the output steadily but slowly drops, about 1.5 lumens every 2 seconds. This didn’t happen with the 14500 LiIon battery.
I measured 288 lumens at 4.23V, 600mA with the 14500 battery and after running for 5 minutes indoors the head gets warm, at 35.6 degrees centigrade with ambient temperature of 21 degrees centigrade.
I suspect a second edit might be overdoing sequential reading. :bigsmile:
Keep up the testing and reporting back. I might even consider joining the dark side, & linking my Debit card to PayPal :cry: , if Justin is prepared to repeat the exercise.
My current NiMHs have been decommissioned due to ultra fast discharge so I’ll have to wait until my Turnigy AAs come in to do the NiMH testing.
I’ll make a new thread that consolidates all the data when I get them.
I don’t really know what else to test, except runtimes. But I’ll do those another day.
The name Slewflash comes from three different parts, slew is a mixture of my first and last name and flash comes from flashlight.
EDIT: I also don’t have any NiZn or LiFePO4 batteries, but I probably won’t be getting them any time soon so I won’t be able to test those.
