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.
I have 18650 flashlights but I still want longer runtime, I am not sure if I’ll get a 21700 or just buy more batteries. But I did order 2 18650 batteries today but still considering adding a flashlight as a back-up or perhaps replacement to my BLF A6.
I’m wondering how the similarly-named SST70 and XHP 70.2 emitters compare. How are they similar? How are they different?
Thanks!
Other than measuring with proper equipment, or trying to guestimate comparing to known light sources, is there any way to know if you’re getting a LH351D in 70/80 CRI instead of 90?
Is this legit? WildTrail WT90 SBT90.2 5500lm 2000m 3*21700 Flashlight And if so, what is their shipping like?