What kind of glue Sofirn use for their drivers?
I would dismantle and re paste it
Searched around a little for some good tutorials…man there’s a lot of junk info out there. Here are a couple good videos and articles that should help you. Nuts and bolts stuff for using meters and basic tests, but it would pay to check out some of the basic conceptual stuff about electricity in general. You’ve already got some letters in the alphabet soup, so it’ll get easier as you gain some more and understanding falls into place. It’s a lot easier to learn hands-on with someone showing you, but videos can take the place of that sometimes and there are tons of “makers” around these days with content (and sites like Adafruit and such have a little bit…these links seemed better to me, though).
This is good and kinda gets straight to the point for you with batteries, then really basic LED circuits (like stuff you might do modding an ultra cheap flashlight that doesn’t have much in the way of a driver to control things). Could be the best seventeen minutes of your life: https://www.youtube.com/watch?v=ts0EVc9vXcs
This channel - “The Engineering Mindset” - is really excellent. He’s done a marvelous job illustrating concepts for general stuff, components, and circuits (and other things) and presents them in a way that is easy to grasp. I found that channel while searching for things about neutral lines (A/C) and some hvac stuff, then saw how many great videos he has. He doesn’t have a good one for basic multimeters but there is this one on battery testing. He shows the correct way to test cells with a small load applied (resistor) so that you can see if a cell is behaving nicely rather than just looking at voltage alone. This isn’t really necessary for our li-ion flashlight batteries but it can be important for lithium primaries (coin cells, etc), silver oxide, alkalines. He does have lots of individual videos covering the basics like voltage and current and resistance and inductance, etc., and when you feel like it those would probably be very helpful for you. But using your meter for the basic nuts and bolts you don’t necessarily need to know all of that. If you search his vids for “multimeter” most of those will come up close to the top of the list.
HOWEVER….safety is important, and other than remembering not to short things out accidentally, I have to mention that our DC low-voltage flashlight circuits and most things on circuit boards and components are generally pretty safe. When you move over to equipment like motors and air conditioners and automotive, you really need to know more about what you’re doing and how those things are assembled, and proper testing procedures for them. There are chances for a nasty shock (larger batteries or current, larger capacitors, etc), and also bigger potential to damage parts (mechanical and electrical both…or your meter).
That video: https://www.youtube.com/watch?v=JjElWj0fFX4
And a couple good articles with some of the same info plus a little more explanation of the settings/symbols on the meter:
All that said, other things you should know about your meter. First is that they need a fresh, strong battery inside. The battery is the power source for most tests…it feeds energy into a little circuit which the meter uses to determine voltage measurements and if the battery gets low and can’t provide enough juice, your readings may get very inaccurate or shift around as you watch the screen. This can happen before any “low battery” symbol appears on the screen. So always remember to turn it off and keep the battery fresh.
The test leads with that meter are on the fragile side of life, so be gentle with them…that’s true for both ends of the leads. Usually the nickled pointed probes that go back into the handles do not have a good design for connecting the wire, and the wires are roughly solder right onto them…and those wires are usually pretty tiny and poorer quality, too, so they’re easy to break just by bending or may break or come loose with a little tugging. If you want to wrap the leads around the unit for storage, don’t do it tightly. You can get replacement leads (actually those same leads are often like $0.40 on aliexpress…maybe $5 if you were to find them in a retail store), but for a freebie and for a cheap meter, it would make more sense just to buy a new slightly nicer meter instead. Of course you can try to fix broken leads, too.
Back to safety. Although this meter will do some A/C basics, it’s really not a great or safe meter for that, in my and most others’ opinions on these. So if you want to check outlets and cords or lamp sockets and such, just be sure you understand what you’re doing so you don’t pop a breaker or scorch something, blow the meter fuse/meter itself, etc. These are best for simple checks on low volt electronics and such, and they do ok there.
Safety and probes……for flashlights and whatnot, it doesn’t matter if your skin is touching the probe tips or wires, components, etc. But do get in the habit of avoiding that whenever possible, and keeping fingertips behind the little protective circle disk things on the probes so skin doesn’t contact them or circuits…it’s just wise. With high powered circuits and with A/C there can be a potential of arcing in some situations, so keeping skin back and touching only insulation is a good habit (and in those cases, better leads are really required). Also a good habit to try and honor polarity (red/positive to positive and black/common/negative to negative)…for many functions the meter will handle it either way without worry but sometimes it does matter and sometimes it’s unsafe to reverse them (for things like diodes/leds it’s kind of mandatory to test operating function but you also check those in both directions/polarity anyway).
When using the leads, remember that firm contact makes a good connection, so press them lightly into the metal of terminals/legs/solder joints, or in the case of bare wire (with flashlights) you can squeeze the wire to the probes with fingers. If you just let the probes barely touch the contacts, sometimes you’ll get inaccurate or wandering readings, and some batteries have coatings on them that you need to get through (or oxidation, even if they look clean). You don’t have to press hard, just firm, and remember that these leads are kinda fragile. Also, wipe off the leads before you use them…a little alcohol once in awhile…just like flashlight threads, any grease or grime there may interfere with good contact.
Anyway, glad you got a meter! Should put your mind at ease and it can be fun to look deeper into your stuff. It’s interesting to see how cells bounce back up a little in voltage after the load is removed from them…some bounce back faster or more than others. You can check out tailcamp current (amps) for many of your flashlights, too…even if that’s not the most accurate/truth (vs current at the emitter itself) you can get a good idea of the power and can also compare different batteries’ delivery.
Assuming you use the appropriate MCPCB, depends on the output current of the driver, it can take up to 4A on Eurekatronix boards, probably less on Convoy boards. Edit : it’s driven at 3A in the S21A.
Well there is likely a sense resistor that you could replace with a higher value to decrease the current, and if the MCPCB is replaceable then it should be a doable mod.
I discovered that my Fluke 73 III multimeter happens to have a continuity test function. All this time… and I could’ve been testing continuity in my life. 
When I made the test on an LED, it did light up though very faint. I’m guessing that’s normal? Just a nominal amount of current put through?
Yes. Continuity settings (and diode-check settings, if there is a separate one) pass some current at low voltage. Varies by meter but many only do something like 1.5v and about 100mA, suitable for biaxial leds but won’t light up most smd leds. Some meters give more juice, or maybe just more juice in a diode-check than in continuity. I got one of the EEVBlog meters last year and it has a more powerful diode-check on it, which has been pretty useful. Neither of my older meters would light up high power leds. Maybe not as convenient but you can always use ohms for continuity as well.
Another good channel is Afrotechmods. Just saw this one on batteries and learned a good bit from it:
I agree, it’s a great idea to have a multimeter handy. You don’t need to be an expert to use one and there’s so many online sources to help you figure out functions, as you listed. I think it’s a good idea to get a quality one versus a cheap one. FLUKE is a brand I trust. There have been some electrician courses where they mandate a certain multimeter, and then afterwards some people drop out of the program and put their multimeter up on eBay. I bought a Fluke 73-III model back in 2009 for $60 shipped, in gently used condition with the rugged yellow outer protective shell (removable). I’m seeing you can still find them for about that much on eBay these days.
Help me with a list of chargers that will be able to resurrect a zero-voltage cell that has quit due to the protection circuit working?
I have an Olight cell that was in a flashlight unused for eight or ten months that has gone to zero, and I’m not sure if I can revive it.
Yes, if I try to revive it I’ll do that outdoors on a fireproof surface
Many chargers can do that, what do you have ? If it’s a proprietary cell that doesn’t fit you can use wires.
Alternatively you can parallel the cell with another cell, a discharged one so that the current isn’t too high (or use a resistor)
Lights with integrated charging also can do that, again if it’s a proprietary cell, use wires.
Just bump start them with another battery. You only need a piece of wire.
I’ve been seeing these relatively cheap ($50+) multimeters on Banggood and AliExpress. They have a wide range of functions. Are they any good? Does someone have a recommendation?
Hm. The advice to
Seems to be illustrated by the “bump start”image, is that right?
I have three different Xtar chargers and one LiitoKala Engineer 260, and a few more tucked away somewhere less used.
You can use a Very Smart charger that knows how to bottle-feed it ’til it builds up enough voltage and then proceeds to charge the cell normally and carefully…
or…
use a Very Dumb charger which doesn’t know its anus from its synovial hinge joint, and happily tries pushing some current into whatever’s stuffed between its two contacts, and then finish off with a Somewhat Smarter charger.
I’m waiting for this package. After the package hit Los Angeles it seems like China Post is just spamming random junk to keep the tracking number “active.” Have you guys seen this before? Is it a cause for concern?
Nope, that’s fine. I’ve followed packages down the rabbit hole, and always got ’em. Arrive at JFK, go Flat Stanley for a while out east, back to the city, various distribution centers, then literally overnight arrived at my local PO, out for delivery, and delivered, all within a 12hr window.
Patience, grasshopper.
No big deal. It hit LA so its switched over to local shippers. The tracker you used says some confusing things about it shipping through China after at got to the US, but a different tracker shows it staying in the US. So just ignore it. You’ll probably receive it in the next few days depending on where you live. Maybe a week since there’s lots of stuff being shipped right now.
O.K. I will try not to screw myself into the floor (too much). Thanks guys 
I passed Westie’s suggestion on to the Olight customer service people (Olight made my now dead battery).
Their CS person has passed it on to their engineer, and I await advice.
I recall there are three or four kinds of protection circuitry, some of which die but once and some of which can be resurrected, so I hope they know which they used in making their batteries.
Aha, the answer came in today’s email:
Well, that’s pretty meaningless. I asked for a clearer answer.
If we want longer runtime, do we buy more batteries or more flashlights?
Yes. :laughing:
I’d say do whichever is cheaper. If its a custom built light or just expensive, buy more batteries. If your talking about cheap lights for emergency use and you don’t care what they look like, buy some more of them (with batteries). If your special light has a cheap 2,000mah battery in it, upgrade it to a higher capacity battery. So it just depends on your situation.