If it’s just to check the wiring/soldering is good then a digital multimeter, though that only works for 3V LEDs, for 6V, 12V… etc then some kind of power supply, could be cells in series with a resistor to limit the current.
For more extensive testing, like characterising their output and Vf, then a power supply with which you can adjust the current, usually known as bench power supplies, then of course the tools necessary for measurements (DMM, integrating sphere/luxmetter… etc)
Have a look through some of user djozz’s old threads…I know he’s shared photos of his testing setup and the evolution thereof. Besides the power supply and shorter thicker leads, something like an old cpu cooler heatsink or similar that you can screw an mcpcp to, maybe some of the cheap white china thermal paste like GD100 or similar HY brand (fine for testing…actually not bad for most lights other than drying out quickly), maybe a small fan for cooling at times. I’m sure you already know that “rated max output”/current from the manufacturers - for most white emitters - is far lower than what they can actually be driven at and far lower than the majority of our lights drive them at. If you want to do graphing there is good freebie software but I can’t remember what it is…should show up in other emitter test threads here.
STUPID QUESTION
Does anyone know if the head of the Foursevens Mini Turbo MKII fits and works with the battery tube of the Foursevens Quarks (16340/ 16650)?!
The best images I can get from these models (well, their recent versions) are here, but I can’t really say if they fit and work :zipper_mouth_face:
I’m probably going to get a lot of different answers from the dealer and from you guys. I guess I got to figure out which one’s best! So I bought some unprotected GA button tops Black Friday sale. Probably won’t need them for 2 years cuz my MJ1 are doing well. The question is, can I store these two years continuous, or after 1 year should I take them out of storage charge them up and then back into storage?
Thx
^
I make a point of testing my long-term stored batteries for charge level every 6 months or so. If they start dropping down below 3.8v, I charge them back up. I don’t have very many. Most of them are laptop pulls, which are lower amperage than the high amperage (over 5A) batteries that I use for high power consumption flashlights.
In general, if you’re not using many batteries for over a year… you’re stockpiling too much. One good exception is non-rechargeable cells that you want to keep on hand for emergencies or quick stand-ins for rechargeables like AA and CR123A. The CR123A is a remarkable cell that can often keep for 10 years on a shelf before starting to degrade.
^
What level do you store them at? You mentioned dropping below 3.8 volts? I store mine on 3.55 or 3.6 volts.
I bought these because they were on sale. As I said I don’t need them probably for a year and a half or two years whenever my other batteries go bad.
Question is if that’s the case, is it okay to keep them stored for two consecutive years checking voltages but not charging them up again unless necessary.
The higher the state of charge the higher the calendar ageing, but specifically there is a threshold around 50~60% where above it degrades faster. So no, stored li-ion cells shouldn’t be topped off, in the first place they are charged from the factory at 30%, due to shipping restrictions but also because it’s a good place to be since it’s under that threshold while leaving quite a bit of capacity for self discharge, which is quite low with li-ion, if the cell goes into negative SOC then it’s bad.
So just leave them as they are, they should be around 3.3~3.5V, you can check in one year and if you see them going towards 3.1~3V then you can get them back up to 3.5~3.6V.
First thing I do is a capacity test which I’m doing right now. After that I store them around 3.6 volts. My question was can they be stored for two continuous years or should after a year I take them and charge them and then put them back in the storage?
If they’re going from 3.5 volts or 3.6 volts down the 3 or 3.1 in a year, something is definitely wrong with those batteries. I’ve stored them for a year and they are the exact same or 100th of a volt lower many times.
The reason I asked the question is cuz somewhere where I Googled it said you shouldn’t store them for more than a year. If you do, charge them and then you can store them again. I never really heard of that method so that’s why I inquired about it.
I’m going to keep it simple!
I’m going to leave them stored for a year check them periodically and if I don’t need to use them after a year and the voltages are fine just let them be until I do need to use them.
That’s the same suggestion my hometown dealer gave me the one who sold me the batteries. He’s an engineer and knows pretty much about these batteries.
16340 batteries (rechargeable version of CR123A)
What’s the “practical” maximum mAh available? I still have a few from olden days, when 650mAh was common. I think the highest I’ve seen is 850mAh (Vapcell). I’m suspecting this would be about the limit—after all, there are 18350 cells as low as 900mAh, with highest around 1500mAh.
_
I imagine like thefreeman said that 3.5~3.6v is probably the ideal, in terms of minimal charge decay. I’ve found 3.8v to be fine and the cells sit at that level for a very long time. Trouble with testing this is that it’s so long to find out! If you have freedom of time, do a test. Have some cells at 3.5v and a couple at 3.8v. Note the charge on the battery (little label), with date. Then do a voltage test at 4, 6, 9, and 12 months. See what happens.
FWIW, you know those old notebook hole reinforcers? They look like flat mini peppermint lifesavers? Those are great to adhere to the positive end of 18650 cells. I write the post-charge resting voltage there, so I know which cells are the best and those that are lesser (for unimportant tasks).
How should I go about getting rid of about 20 LiIon cells?
Just drop them off at Home Depot?
They are all still nearly new, not dead.
Post in the WTS forum for Canada… maybe there might be someone nearby on BLF who’d be happy to take them off your hands?
Hjeh, I was just gonna jump in with “No prob, I’ll take ’em”. 
Lots worse, relatively speaking.
If you leave lithium ion cells in a charger, and the charger is not plugged in, do the cells discharge more quickly than if they were not in the charger?
Usually yes, how much depends on the charger, this is something that HKJ always tests so check this on your charger review from him.
For example my charger: Review of Charger Zanflare C4
Which is pretty significant
Thank you, thefreeman! 
I recently ordered a heat gun. Should I get a hot plate in addition? What do you do with a hot plate?
I bought a temperature & air flow controlled heat gun during the recent sale. It is called “T12 Heat Guns OLED Digital Display Temperature Soldering Station”. I thought having a heat gun can be useful. I can think of several interesting uses for my heat gun. Heating flashlights to loosen glued threads, heat glues and stickers for easy removal, and possibly remove and reflow LEDs.
However, I heard that reflowing LEDs on MCPCB using heat guns may not be easy because MCPCB can soak up a lot of heat and LEDs can be damaged by heat. Temperature controlled hot plate seems to be an adequate tool for working on LEDs. However, I don’t think I will replace LEDs often. Many of lights I own have RGB aux leds and they are not mod friendly because of the small wires and tight spaces.
If I am not going to reflow many LEDs, what are other uses for a hot plate? Only other uses that I might have is heating cold coffee on the hot plate. The model of hot plate I have in mind is MECHANIC ET-10 hot plate. Price is not bad at 30 USD.
Good question! Wondered about that myself but never thought to ask.