The There Are No Stupid Questions Thread

Folomov also has a similar charger. I like Olight more because it feels like it has better quality and because it detects polarity by itself but Folomov doubles as a powerbank and is cheaper.

Or, a crap ma stank.

That’s an interesting question. Sort of like using stops on stock. The stop works during the trading session, but stops do not work if a huge gap occurs when the market is closed.

What a cool analogy!

This must be an old question as I don’t recall it. Was it answered?
Most ui like Narsil and Anduril don’t monitor the voltage when the light is off. The mcu basically goes to sleep in order to reduce parasitic drain.
The only thing I know that can protect against low voltage when off is a built in protection circuit in the battery, aka a protected battery.

I’m new to all this stuff and I have two “not stupid” questions for y’all.

Trying to learn about all this and I have several random LEDs or boards with LEDs that I have easy enough access to. Old and or broken torches that I wouldn’t be afraid to tinker with. But I don’t know the first thing about LEDs or batteries. Understanding of electrical concepts isn’t entirely zero, but experience with these two things are definitely more end-user than engineer.

My first question is:
What, if any, characteristics of a “mystery” led can be determined without knowing anything about it? Like, with a multimeter or something.

And the second one is:
Does anyone have any recommendations for where to find good and fairly complete information on soldering? Tools and techniques, trusted brands, that sort of thing.

Thanks :smiley:

To identify an unknown led I would first look at it’s base dimensions to narrow it down and then try to match the die and dome. Here is a reference page with all the leds. A multimeter will not tell you anything.

For soldering I like the KSGER plug in models (not battery) that use the tips with the heater and temp sensor built in. Like this model. It’s about $45 plus you can get a lot of different tips for not much money. They heat up super fast, like 6 seconds and have accurate temperatures (accurate enough). You can also get a stand and a tip cleaner pretty cheap as well. I did a video of those parts here. There are a lot of good soldering videos on YouTube. Having a good iron, flux, solder, tip cleaner, etc makes a big difference to the results. These quick heating tips are able to feedback temperatures very quickly so when you go to solder on something with large mass and it pulls a lot of the heat out of the tip it can sense it and dump heat back in quickly so you get predictable results. Its way better than the older style soldering irons with replaceable tips.

That’s what I was afraid of with the LEDs. Some of these are probably not easily identifiable. The torch LEDs might be easy enough to ID, though.

Thanks for the tool advice. Guess I’m off to YouTube :stuck_out_tongue:

Question:
When you buy new lithium rechargeable batteries that arrive not fully charged… does that mean they’ve never been fully charged? Or are they charged and then drained to the safe minimum as a matter of testing? And then some makers may decide to leave them as-is and not fully charge before final packaging?

Also, when you do get new batteries that aren’t fully charged, is it a good idea to fully charge them, then discharge by some amount, e.g. 20%, before storing? Or is it absolutely fine to leave them as-is for possibly long periods before finally being put to use?

There are FAA safety regulations for shipping lithium batteries that says they are supposed to be shipped at about 30% or so which is about 3.6 to 3.7v for a 4.2v cell.
Resellers don’t have time to charge up batteries. (Edit, it seems some might do a quick charge and test before selling)
I doubt the manufacturers have time to charge and discharge either. (Edit, it looks like manufacturers do indeed put some charge into their cells before shipping them out). They might spot check batches for quality control, but I doubt they do any more than that. They crank out cells by the thousands.
Each manufacturer has they own storage specs for the cells they make.

Here is the 30Q storage notes as an example:

Storage
4.1 Storage conditions

4.1.1 The cell should be stored within a range of temperatures specified
in the product specification.

4.1.2 Otherwise, it may cause loss of performance characteristics, leakage and/or rust.

4.2 Long-term storage

4.2.1 The cell should be used within a short period after charging because
long-term storage may cause loss of capacity by self-discharging.

4.2.2. If long-term storage is necessary, the cell should be stored at lower voltage within a range specified in the product specification, because storage with higher voltage may cause more loss of performance characteristics.

8.8 Warning – Attached
Handling precaution and prohibitions of lithium Ion rechargeable cells and batteries Inaccurate handling of lithium ion and lithium ion polymer rechargeable battery may cause leakage, heat, smoke, an explosion, or fire.
This could cause deterioration of performance or failure. Please be sure to follow instructions carefully.
1.1 Storage
Store the battery at low temperature (below 25℃ is recommended), low humidity, no dust and no corrosive gas atmosphere.

.

That’s it. Nothing specific about voltage. I guess for long-term storage you want it a little bit discharged like maybe 4.0v

^ Thanks, Jason. That seems to make good sense.

So when a rechargeable lithium cell is manufactured and assembly is complete, what is usually the inherent charge level at that point? I’d expect it wouldn’t be fully charged. Is the partial charge you can find for a new cell the charged state at which the cell is naturally at upon assembly completion?

I know some rechargeable cells can be bought where they are already fully charged up, like NiMH. I don’t know if there’s a post-assembly process where they are put into an automated charging routine just prior to packaging… or if manufacturers figured out how to do it such that the assembly completion delivers a totally charged cell. Anyway, I figured it wouldn’t be much different from lithium cells.

Jason laid it out nicely. I’ll add just a little. Not sure about some of the Chinese cell manufacturers but with the big brands the cells are charged fully and then discharged to nominal voltage (3.7v for most….3.6 for some older chems/models) for storage and shipping. They do this for quality assurance and then for best-practice care while the batteries are dormant waiting to be installed and used by product manufacturers (or us shunned end users with single-cell off label uses). I don’t think any cell retailers really do further testing/charging but there are at least a couple that do check arrival voltages and may perform voltage checks while they have the stock and/or before shipping them out to customers. Not sure if this or anything else happens with manufacturers that are assembling packs or including cells in other devices.

That 30% state-of-charge figure is indeed required for safer shipping (in the US and many other countries although there is some slight variation, depending on country and device/capacity/type). That brings it roughly to the 3.7 nominal voltage. That said, I have received cells that were above 3.8v and many that were around 3.4v or a tad higher, and twice received some that were above 4v.

There are two lines of thinking here. For transport, it’s all about reducing risk, and cells that are at a low state of charge have much less chance of significant venting or arcing if they happen to get mashed or shorted or something…not risk-free of course, but less. The other is just the known best-practice for retaining maximum capacity and maximum cell cycle life. This comes from years of exhaustive testing by the big brands as well as observations from users. Basically when we charge up a li-ion to 4.2v, it’s considered 100% charged but it’s actually an overcharge which is not ideal for the ideals. For us as flashlight users, it really isn’t a big deal and most of use don’t worry about charging them there (most chargers are programmed to do it anyway) and don’t worry about storing them at home at that full charge voltage. If you reduce the charge termination voltage you lose a touch of capacity/run time, which is fine for most lights but will usually affect turbo modes a little, but in doing so you increase cycle life of the cell significantly. As for storage, you can consider the (minimal) self-discharge rate of the cell and also the potential to permanently lose a little of its capacity - the higher the state of charge, the higher the discharge at rest and the higher the loss of capacity. This is also highly dependent upon temperature (room temperature-ish is standard, if you can store them a bit cooler that’s better but no need to refrigerate them (which would also introduce humidity concerns for most fridges)).

So if you really want the best, don’t charge them up quite as much, drain them to around 3.8v give or take a little for storage, and keep them in a nice museum environment with comfy temperature and low/normal humidity. Or mostly ignore it and just run with it…generally fine. The one thing you do want to avoid if possible is extended storage at higher temperatures, where you will see some permanent degradation, and try not to discharge them too low all the time (3.2v to 3.4v is functionally empty but of course they’ll still run on low modes/low current draw for much longer…3v is a good low limit but if you go lower that’s not horrible as long as you don’t allow them to remain at those low states for a long time…just charge them up reasonably soon and they’ll be fine. And discharging below 2.7v…increasing risk of damage but they usually recover fine if you charge them.).

A lot of this best-of is much more important to the primary manufacturer of the cells and to manufacturers of devices that buy many thousands of cells at a time for production use. Everyone wants to deliver their customers grade A performance and to minimize defects/returns which are costly. And it’s perhaps much more important when we are talking about packs which use many cells together in various configurations. But for flashlights, especially just single cell models, not a huge deal unless you just want to adopt the methods.

Here are a couple of links to BU. Great site, quite exhaustive and not always easy to navigate, and some of it is “old” information but largely as true and relevant today as it was when written. Easy to get lost in the sauce and technical info here, but these are a couple basic articles (many more if you feel like going down the rabbit hole):

There is no charge when they are first manufactured. This site explains that they overcharge them slightly on the first charge.

That reference page is golden…doesn’t quite show everything but it puts you in the ballpark and most of what we use in lights is on there. That said, in cheapie lights you’ll often have mystery emitters and many made good effort to replicate various Cree models (sometimes very good fakes). Latticebright models were (are?) a popular cheapie emitter found in a great many lights. I think we have a thread on here somewhere about identifying fake Cree that had great Latticebright examples, if you search for that one. If you can’t figure out what you have from that reference page, people here will help if you give photos (or maybe the info is in the specs/reviews for the model of light), or you can look up the manufacturer datasheets and look toward the end for the spec drawings which give measurements and also a view of how the contact traces on the bottom of the emitter are laid out.

So visual familiarization and die size are best, but you can use a good multimeter for some basic tests. The diode-check function on many meters can be used to see if the emitter is good, although for our higher power and SMD emitters the function on the meter should deliver at least 2.5v or more. Most meters use an unhelpful diode-check that only has a half volt or perhaps up to 1.5v so that’s only good for bi-axial old school led’s (and for normal diodes of course). You can also check for open and reverse voltage/leakage with this test but we don’t see emitters fail like that often, so just the basic light-up test is generally enough. (You can also do this with a battery and a couple leads/wires that you hold by hand if your meter doesn’t give enough oomph on that function.). When doing the test, just connect things briefly to see it light up. If you hold them and allow the emitter to keep emitting, there’s a chance that it may overheat and suffer damage or death if it is not mounted to an mcpcb/heat sink. To do other performance tests you need to test while in the light itself and/or set up a test rig using a bench power supply and such.

That’s a neat site, love seeing the machines and processes…thanks!

I was told by a Samsung rep years ago that they did charge and discharge new cells off the line. I don’t have the email anymore but it was probably about 2014 or so. I don’t know if they’re so easy to get in touch with these days but I used to have great luck communicating with them, even got a storage/SSD systems engineer one time that provided a ton of fantastic information.

Maybe a quibble but a point to add is that every battery - no matter who makes it - must receive at least a forming charge, else there is no finished product (can’t do that at home). Probably not what you meant, though.

Thanks, Correllux! That answers many of my questions. Makes a lot of sense, for Lithium-ion cells to be at a lower charged state for safe transport. So they likely have an automated routine at the tail end of the production process prior to packaging.

I’d bought a bunch of new cells just recently and their charge levels were a bit mixed. The two 21700 cells, different makes and mAh capacities, were showing initially 3.4v and 3.5v. Some of the 18650’s were at 3.8v. That’s what triggered my curiosity. Anyway, I’d forgotten about Battery University and will check the links on best practices. I can go some months without putting some of my flashlights to any serious use, so it seems a sensible idea to be mindful of the battery charge level and adjust accordingly for longer battery life.

Yeah I meant when the can is first welded shut. That site seems to be more in the business of producing battery packs rather then trying to sell individual cells. I would assume all manufacturers go through a couple of cycles before packing and shipping. The reference to grade A, B and C used to be more common. It’s not something you hear about often now. Makes you wonder sometimes?

I also wonder about variances in production methods by cell type. 18650’s are a cash-cow cell, first made by Sony in 1991. The method of manufacture is mass batch and streamlined. What of 21700 cells? First made by Tesla in 2017. I imagine it’s licensed and made by a variety of manufacturers. I imagine the assembly process is very similar to the 18650. But outside of battery pack building done by Tesla, maybe 3rd party makers do things a little differently from the 18650? A little more manual process?

Who offers emitter swaps for the most reasonable prices?

OR

Is it overly ambitious for someone who doesn’t know how to solder yet to buy some things and swap their own LEDs?

Projects I have in mind:

  • put 2850k XPL-Hi emitters in a Thrunite TN40S
  • swap out SST40 for SFT40 emitters in a Sofirn SF47
  • pull 5000k XPL-Hi emitters from a lemon D4V2 head and place them in something else (not sure what yet)

It is relatively easy to unsolder the two wires from the mcpcb and swap in a new mcpcb that has your new leds installed. This mainly comes down to whether you can buy the leds you want on a mcpcb that fits. This has the advantage of changing the led footprint such as swapping from 3535 to a 5050 led.

If you cannot get a loaded mcpcb then you are limited to reusing the stock one. This means your new leds have to be the same footprint and you have reflow solder it. This is much more complicated and usually requires a hot air station or a hot plate. It’s a more advanced technique.

So you have to do your research and look for the parts you need. In the US, Mountain Electronics is a good source of leds already reflowed onto mcpcb. He can mix and match whatever he has in stock. Otherwise you’ll have to find a preloaded mcpcb probably from overseas.

It’s definitely smarter and cheaper to buy a solder iron and learn the basics yourself. Then you can at least swap parts and fix wire connections, etc… Having to ship lights to people for simple swaps can get very expensive, be time consuming and you risk a package being lost or damaged in the mail.