Completely off topic.... juz cuz.....
I've been using mechanicals for the most part this year. I've also been playing with rebuildable attys. An odd thing occurs when you pair the two. Sometimes you find the vape or flavor drops off. Sometimes a coil has gotten gunked up so it's not firing quite right. Sometimes the battery has died enough that it needs to be changed out. Most of the time, it's rather inconvenient to check the coil so it's easier to check the battery first - but then you have to haul out the multimeter and fiddle with it until you can get the contacts placed properly.
I decided that this was way too hard (mostly because I'm lazy and would prefer to spend my time doing useful things.... like filling my glass or just peacefully vaping). I built a battery tester because the two that I already had were too small to accept an 18650. Turns out that FastTech sells little LEDs specifically for testing batteries and they also sell battery holders. I ordered both pieces, opted for free shipping and sat back to wait.
As luck would have it that the order didn't cost enough to warrant USPS and ended up coming by China Air or something like that (apparently that means that they attach the package to a balloon and float it across the Pacific via some kind of convoluted jet stream). Eventually it arrived (I now keep bits and pieces listed to add to any shopping cart to make the shipping faster).
It took a couple of minutes to make it work and then a couple of days to cut down the battery holder and add a plastic case for the LED. So now I had a working battery tester and when things didn't taste right, it took about thirty seconds to take out the battery and decide whether I needed to replace the battery or fix the coil.
Then, one day, things weren't right, I dropped the battery on the tester and nothing lit up. Blue air began to surround me (I have little patience for poor craftsmanship) - I proceeded to take the whole tester apart and even hooking the battery directly to LED produced no results. In a rare flash of inspiration, I hauled out the multimeter and tested the battery.
Seems that the LED needs at least 3 volts to light up - anything less and it just plays dead. I'd have known that if I'd understood the description when I was buying the thing - who'd ever think that something that reads 3-30 volts means that below 3 won't work and above 30 will probably self destruct (I know, anyone with a functional brain).
So now I understand the quirks of the beast but I'm still a complainer (yeah, complaining is one of those "useful" things I'd rather be doing). If the meter was made to test 18650 batteries, why does it have 3 number sections and only one decimal place (it reads 04.1 instead of 4.10). It should read 3.00 to 4.22 or something like that - or better yet, 2.00 to 5.00. So now I have new mission. I absolutely "must" find one somewhere for less than $2 because I'm not only lazy, I'm cheap (or poor, take your pick).
We now return you to your regularly scheduled program.....