Cheap torches

[Lango1818]

Chinese EBay magic torch.
I purchased a torch from EBay recently because I wanted a reasonably bright cheap torch.
Of course nobody believes the absolutely ridiculous claims made by the manufacturer.
Such as 100000 lumens, water proof if you do not put near water, just to name a few.
I was happy enough with the build quality for the price of $25 Aus delivered. Solid aluminum body and a bright focusable beam.
 What does concern me though is the torch is run by 2 26250 rechargeable lithium batteries. The batteries are in series and have no battery management system as there is no sense wire connected between the cells. The torch is charged via a usb c port in the side of the torch. How long before one of these torches catches fire and possibly explodes. I take the batteries out of the torch to recharge, I was going to buy a couple as gifts but once I saw the charging arrangement I changed my mind.

[coppercone2]

if its simple I expect it to last a long time. I got a 2x 18650 torch on dealextreme in like 2011 and it still works but the switch is shady.


But as soon as it has some kinda digital display ETC it gets fragile. IMO get a old fenix online used, clean and grease the threads and buy a new battery from the manufacturer, you end up getting premium stuff at a fair discount. IMO the brand name protected batteries are reliable, but their expensive, so your super cheap torch ends up not being so cheap anymore.

People will upgrade perfectly good brand name lights because the lumens got up to 2x higher in the same form factors. I got a few, but I noticed now on the super mode its so bright it hurts the eyes for close range on the max modes. its still useful if you shine it at ceiling to illuminate a room or for long distances, but that 1000 lumen light that turns into a 2000 lumen light, you are not getting as much from that 1000 extra lumens as you think for regular use, I would say its only for a small portion of the use... unless you are doing out doors activity..  but even so, people from 1980 would not find 2015 flashlights much less impressive then 2025 flashlights.

the #1 use for the ultra right settings (i.e. small form factor flashlgiht with 3000 lumen) is mosquito hunting. they like glow and you can get them easier



And for the ultra bright lights, the new ones DO have a benefit. I.e. the newest fenix brands at the crazy levels of brightness have a sensor that decreases the brightness based on IR thermometer. So it will turn to a low mode if you set it down on a table upright. This saves your battery and possibly other stuff (i.e. molten plastic tarp etc).. and it reduces your eye strain if something gets in the way of the flashlight so it automatically turns down instead of reflecting in your face off a white surface. It's measuring the temperature of the area right infront of it, so if it detects something is getting roasted it will turn itself down. When I was playing with color light gel films, they get warped really quickly from the intense heat but then they don't melt because it turns itself down. I can see that preventing you from blowing a hole in your tent or something.  .. then you got ants unless you have duct tape


But for outdoors IDK, I would just shell out because you can literally die if you trip on a root or something going down hill at night, having the most light means you will spot obstructions like vines, roots, loose rocks, etc. a couple of hundred bucks not to spend 2 days in the bush with a broken leg before hopefully fido finds you because you stepped on a pine cone and tumble down hill :'( . The ER bills are so scary too having a good flashlight is worth more then health insurance too.. someone here tripped on a cardboard box piece someone left on the stairs and broke their forearm because of bad lighting.. i don't go out at night without a good light.. and I know one very successful guy that got taken out by sepsis after he broke his leg on a tomato plant potter. probobly would be alive still if he had some lumens

[Rick Law]

Chasing bright flashlights can be kind of fun.  First upgrading the LED drivers (with a Attiny13 MCU based driver) and then upgrading the MCU to ATTINY85 to load my own MCU controller program.  Then, upgrade the emitters and again when a newer better one is available.

But, back to the point I want to make, 100,000 lumens is definitely horse crap.  If you don't know how to get an estimate and your flashlight has a zoom mode, here is a quick way:

Measuring lumens is kind of hand-waving magic anyhow.  Since lumens is the 360 degree 3d output (all directions spherical), you need to capture and measure the entire spherical shell surface.  To accurately measure lumens, one has to build a sphere with sensors covering the entire inner surface to capture all emitted light, or a no-loss lens/reflector to focus all the light in one direction (and then hand-wave magic about spherical surface vs flat).

Lux on the other hand is 1 lumen projected onto 1 meter-square surface 1 meter away.  So, if at 1 meter away and project to 1m² you measure 100 Lux, you know is 100 lumens.  Lux can be easily measured using a Smart Phone^[1].  Since this sensor is for back-light illumination adjustment, it is not so accurate but at least it is a consistent gauge of brightness.  The variation I see between my Smart Phones suggest at +-25% (and also as compared to my actual lumens meter which is probably not that accurate).

You can project your light 1 meter away onto a 1 meter-square surface and do the math.  One meter away is easy.  To project the light to 1m² you need a circular area of 1m², so radius is r=(1m/3.1416=0.3183m) r=(1m/sqrt(3.1416)=0.564m).  You need to adjust your flashlight's zoom accordingly to get it to project to a circle of r=0.3183 0.564 meter.  The flashlight probably has a brighter center circle and a dimmer outer circular ring, so the Lux in the two areas should be separately measured and prorating the two numbers by the fraction of the two areas.  If the bright center is 20% of the total area and at 200 lux, and dimmer outer is 40 lux, you have 20% of 200 plus 80% of 40.  That would be your estimated total lumens.  It would still be an approximation as even within the brighter center circle, the lux will be higher when nearer to the center.  You can of course use average within a ring, or may be dividing it into more rings, but that difference will be smaller than the difference due to the Smart Phone's ambient light sensor accuracy.  Not really good, but better than 100,000 vs may between 1200 to 3000.

Note:
[1]  If your Smart Phone have a diagnostics mode (my Asus Zenfone 2/2e, 3 do), use that.  If not you can use an app, download the CPU-Z app.  Under "Sensors" tab, you should find your Ambient Light Senor, it will show you the lux received by the ambient light sensor.

Edit: Minor wording to correct grammar.

Edit 2:

Just to make sure subsequent readers get the right numbers in case the reader read only this but missed Kjpye's later reply, I corrected this post.   Kjpye is right, I made an error by forgetting the square root.

...
Your calculation of the required radius is wrong. The area of a circle is πr², so for an area of 1m² you need a radius of 1/√π or 0.5642m.

[kjpye]

You can project your light 1 meter away onto a 1 meter-square surface and do the math.  One meter away is easy.  To project the light to 1m² you need a circular area of 1m², so radius is r=(1m/3.1416=0.3183m).  You need to adjust your flashlight's zoom accordingly to get it to project to a circle of r=0.3183 meter.

Your calculation of the required radius is wrong. The area of a circle is πr², so for an area of 1m² you need a radius of 1/√π or 0.5642m.

[Rick Law]

You are right, I forgot the square root and had only 1/pi.

[Buriedcode]

Did I missed a reply here? The OP talked about the safety of the batteries and charging without apparent cell balancing.. and the replies are about.. lumens?

[soldar]

I was ready to discuss pitchforks and burning heretics but I see this is not the topic of the thread either.

[Rick Law]

Did I missed a reply here? The OP talked about the safety of the batteries and charging without apparent cell balancing.. and the replies are about.. lumens?

No, you did not missed a reply.  The OP was impressed by the brightness, so nothing wrong with asking "how bright?"  Figuring other than photographers, few would have a lumens/lux meter at hand, I suggested a quick way to measure the lumens -- hoping he may have the time to experiment and reply XXX lumens.