>>>>>>and find out the 18650s that come out of laptop batteries are unprotected which potentially = BOOM.
I actually think that *fire Chinese junk batteries are FAR more dangerous than reputable brand-name batteries (Sanyo, Panasonic, Samsung, LG) from a pack. But that’s my opinion and many think just the opposite. But even dissassembling a pack can be extremely dangerous. You’re wrong if you think the pack will come apart in an orderly manner and without busting off pieces of plastic and perhaps causing a short circuit that could make the boom you’re talking about. So I would read everything you can find about disassembling packs before trying it. And definitely have somewhere to chuck it FAR AWAY if you get a short and it starts to heat up. It happens VERY quickly. Literally one second it’s cool and three seconds later, it’s too hot to touch.
And then once the cells are out, they need to be tested and dubious cells chucked. So a good DMM is a must. And since there is no protection circuit, I have to do that for the cells and insure that they don’t discharge too deeply.
The cell wrappers inevitably get nicked up during removal, so it’s best (I think) to apply a second layer of shrink tube to prevent shorts. Then they have to be CAREFULLY charged and monitored and tested. Unless, you are willing to go through all this, don’t play with packs. Heck, don’t play with li-ion cells at all, unless you read all about them and have a good idea of the dos and donts.
And the commenting poster is absolutely right, you do not know the history of these cells — but then again no one knows the history of ebay or DX cells or even if they’re rewrapped fakes. At least with a laptop pack, I know that a top company spent some time choosing the batteries and wiring them correctly to keep them safe and to insure long battery life. Unless some idiot rewired the pack and was plugging it directly into the wall or some such foolishness, the hardware in the pack SHOULD keep the batteries in good condition, with proper charge times and proper charging current and proper voltage draining protocols.
The way I think about it, no one ever thinks twice about buying a used laptop and used battery pack, and I certainly hear next to nothing about used battery packs blowing up when used as a laptop pack. So as long as I observe the same charging guidelines with the salvaged cells, I think I am as safe with single cells as with a li-ion in a power pack. Certainly safer (IMHO) than any *fire Chinese battery. Because — again — the pack (if working properly) was maintaining the cells as they should be maintained. Bad cells should be easily recognized by low voltage, inability to hold a charge, overheating while charging, low initial voltage, leaking, discoloration, etc.
BUT I will NOT use unprotected cells in a multi-battery flashlight or in any type of multi-cell arrangement without protection circuits of some kind. Look at the pictures of injured law-enforcement personnel in the infamous FBI li-ion battery warning to see just how real the danger is of improperly using multi-cell lights with dicey li-ion batteries.
I only have scratched the surface here about salvaging packs and li-ion safety. And — yes — li-ion cells do blow up. I had one go (thread somewhere on BLF about it), so I am now extremely careful about all facets of li-ion cell use.
I won’t comment on the pvc pipe thing because I don’t understand what you’re trying to do.
Above all, be careful. When one of these 18650 li-ion cells “vents with flames,” the resultant explosion can be big enough to maim or kill you or a bystander. That is no exaggeration. However, it is a fairly rare event. And as has been mentioned before, nicd cells can also blow up if shorted or charged improperly, so the dangers of batteries seem to come with all batteries, although li-ion cells seem far more volatile.
Hope this helps.