Rumour has it he is lucky to get 4 hours sleep per night 
Well, his work is one of the very few where you can only test your work during nighttime only!
I have 4 Vapcell NCR21700A. Two recessed top and two button tops. I tested all four in my PL47 219B and PL47 XP-L HI. They work fine just like any other batteries. My recessed top was never charged because I haven’t bought a charger that can charge them yet so I haven’t tested the recessed version under full charge.
Just find some small magnets and they’ll charge fine (Home Depot has some)
What goes wrong in your reasoning is that you use lux while your reasoning is correct if you were to use lumen.
If you are at 1 meter from a light source (say, that illuminated watertower), the amount of light captured by your eyes is A lumen, coming from a light source that has a surface area B . If you move away to X meter, the amount of light captured by your eyes will be A / X2, but the apparent size (surface area) of the light source is also reduced, by the same factor X2. So the intensity of the light source remains the same, but with X2 less light from a X2 smaller source.
Doubling the distance does not reduce the light entering a certain area (eg. your pupil or the sensor on a luxmeter) by a half, it reduces it by 1/4.
^ sure enough, that is what the 2 stands for in the X2 (X square) in my story. This is not what the reasoning is about, and the picture does not explain what the reasoning is, it does not show that the observer not only receives less light through his pupil but that also that it comes from a smaller source (which part the picture is not about), leaving the intensity (how bright it looks) the same.
As long as the light source has a finite size on your retina, such as a recognisable water tower (it does not appear as a point source) this is valid.
Same happened to me, but with LG that I bough with the light from Fireflies. At first it worked fine, but after I unscrewed battery tube and screwed it back, it powers by screwing tail cap only. Button does nothing.
Good to know, seems like an issue with the light and not the batteries.
Could it have something to do with the magnet in the battery affecting the switch?
Mine lights up if I made contact between battery negative and battery tube with a tweezers. No magnet and same problem.
You may get more views and better answers on the pl47 thread…
My Horror Story 4 Your Entertainment!
Phuong’s car broke down yesterday at the mall. Car would not start. Dad came gave us a jump start. Car started barely drove out of the parking lot and noticed light flickered and steering got super stiff. Repark and inspect thinking it might be low on power steering fluid as there seem to be a loud motor whine driving to the mall. Car is a IS350 bought used at 52K Miles. Had a motor whine when accelerating from day one. It was annoying but I thought that’s just how the car was. Today thinking it’s a power steering issue pop hood and looked the for oil reservoir. Found none. Google and realized its electric assist steering so there is no oil. Google Google Google, Uh oh…Its an alternator issue. Went home bought alternator, research, and people claim it’s a 2-4 hour job. I was like must be 2 hour for me. I have done this before in other cars. Came back next morning with alternator and new belt to dead car early in the morning but rain was heavy. Arghhhhhhh went home and called friend mechanic for advice. He said fully charge the battery and you can drive on battery power for may be 10 miles. Take it to him for $250 installation or take it home and work on it to save some money. Mall to car was about 10 miles. Mall to his house was 10 miles. Went back to car remove battery, took to AutoZone for free battery charge (Thank You). Came back, pop battery in, drove home fast, nervously but ultimately arrived home safely. Now that we are under the canopy that dad and I constructed last summer the car is MINE! Took out all the tools. Turned timer on phone and determined to complete the job in 2 hours. Just 1 hour in and I already regretted the job but there was no turning back. I don’t want to tow the car to the shop and waste another $200 that I am trying to save. After all that is said and done both my hands were scraped, bleed everywhere, made a complete mess, dad came out to struggle with me, his hands scraped as well. Took us 6 hours for the swapped. Ran into issues with everything. Murphy’s law clearly applied. Excuses, excuses but here goes: Battery mounting bracket was bent by previous owner/mechanic. Couple of screws got dropped down the diffuser plate that was so hard required dropping the bottom cover to recover. The cheap tools wasn’t for the job. Even had to grind down the alternator bracket for it to fit. It was a refurbish alternator. Factory one is like $500!!! The space was so cramped that even with my small hands I was scraped all over and there was no way to take it out from the bottom. How the heck does anyone with larger hand do this job. ECU box had to be removed too! Leg and back hurtled so much. Woke up 9AM and didn’t complete until 6PM. So why this long story?! Sometimes is better to let the pro do their thing. Don’t be cheap if I know I won’t enjoy it and can afford it. Problem is sometime I just won’t know how tough a project is until I get into it so it will happen again. Happen every time. Too much eggo and being cheap always gets me…Glad it’s all over! Glad I am back at my desk doing the thing I good at and enjoy. LOL Cheers!
Oh car drives amazing now. No more whine at any RPM and it feels more responsive and even faster. I am sure the alternator add another 50HP and it was worth it!!! AHHAHAHA 
Sounds like a Fun time—- My daughters Accord this summer did me in —Alternator and 3 Motor Mounts —- Saved around $800 doing myself —man that job sucked—- at the end—I got my usual—- Thanks Daaaaaad
PS—- Let Phuong drive the Vette for a while——- 
She loves the F150 and drives it all the time but he rather ride in the vette. I encourage her every time we take it out but the low ride height and long nose intimidates her.
That’s probably best for both of you’ll —- my wife has her own way of driving (that’s why she sticks to her Q56) besides if she takes my van or P/U she always comes back with some kind of crap—she says I love these big trucks—-LOL
Hahaha. Usually the projects that I think will be easy end up being hard and the ones I think will be hard end up being a breeze. Go figure….
Glad everything turned out good in the end Vinh!
Wow, quite an ordeal...
Totally unrelated, I see you are selling PL47's. Have you tried to get access to the LED's, removing the front end bezel? It looks really tough. I don't see any lip like Olights and other lights have, plus we know they are press fit, no threads (from one buyer who got a PL47 with no bezel or glass):
I have not tried to remove one. If I did I would just crack the lens (buy replacement), pry out the SS ring. Replace the LED and MCPCB if needed to adapt it to my preferred 10621 Carclo for more throw with most of the lumen in the hot spot and close to zero spill. While I am at that I would also add a conductive spacer to lengthen the tube to adapt it to longer cells. Problem is I cant get over how the blockey head the light is and poorly designed included headband and it made me lost motivation for any mods. I also find the stock lights to have very inconsistent beam and tint. I ordered all SST20 4000K. Some have nice tint. Some a bit off. Some has nice beams,some with tons of artifacts. Likely poor assembly with seating of optics when the SS ring was pressed in…
Yeah, there's been a lot of quality problems. Mine is the same setup w/SST-20 4000K 95 CRI, seemed to be the great high CRI option. I like the beam/tint of mine.
Ok, good to know about breaking the lens. Thought maybe the bezel could be notched but that damage would be permanent - not so easy to replace the bezel.
Thanx for the ideas!! No immediate need yet.