My favorite website/dealer for cells is Orbtronic at Orbtronic.com
Their cells are VERY high quality (manufactured by Panasonic) and you can get some really high capacity cells there, as well as high drains one for the current hungry flashlights. They have very fast shipping and excellent packaging. All the cells I’ve gotten from them have performed perfectly well and after almost 6 yrs, I still have some 18650 cells from them that are at very close to their original rated capacity. They also carry Samsung and Sony cells, as well as non-Orbtronic branded Panasonic cells.
I recently bought two 21700, 5000mAh buttontop protected cells with a 10 amp discharge rating and subsequently got a 2 bay fast charger for 21700 cells after realizing the cells were too long for my Opus BT-C3100. It’s the Xtar SC2 and it’ll charge a single cell at 3 amps or 2 cells at 2amps each. They also make a 4 bay charger but I don’t have too many cells and I’m definitely happy with the SC2 for now.
I’m just a rank newbie, with less than a month as an 18650 owner. As such, I don’t claim to know anything for certain, but as for the opposite, I’ve read that there are button top cells that aren’t protected. So I guess I might have just said “protected” and that would have implied button top … but as a total newb, I am still very much in “I don’t assume anything” mode.
According to something else I’ve read, these things have about as much energy in them as 1/4 their weight of dynamite. So, yep… I’m planning to be pretty careful about not assuming anything.
Honestly, I think modern protected lithium ion batteries are very safe, unless you’re extremely negligent and do things that are against common sense. I’ve never even been close to having an issue with a lithium ion cell, much less had any risk of danger. Idk why there’s such a stigma around lithium ion cells and how “dangerous” they are. Sure some defective units have blown up in the past, sure they can blow up if you’re an egghead and you handle them very incorrectly. Outside of that, I see no reason to be scared. It’s always good to be careful though, and with the way you’re talking, it seems you’ll be just fine and in the group of people who never encounters any issues.