I got about 7 laptop battery packs, and tore them apart. Here are the notes.
1. They are much harder to open than I thought. I required the full set of tools such as hammer, screwdriver, dremmel tool even. The first pack I opened, I accidentally drove the screwdriver into the side of a 18650 cell and this smell started coming out of it, a drop of something liquid was coming out, and it was getting a bit warm. So I knew I had a thermal runaway reaction going on, expected the worst, I threw it in the glass jar I had handy and took it outside. The other times I was more careful.
Should wear gloves as the sharp tabs soldered to cells are extremely sharp, I cut myself twice with them, while prying the plastic cases open. The plastic casing for the packs is very sharp too. One or two cell packs is not bad, but trying to open 7-8 at a time, well took me over an hour.
I planned to rebuild my laptop cell pack with Panasonic 2900 mAh cells but now I say, no way I can put it back together or even safely take one apart. Just much safer and easier to buy a new one.
2. I had about 1/3 that were clearly good, at 3.7V, discharged but not catastrophically. About 1/3 were completely dead, as in 0.01V and about 1/3 were questionable, that I will try to revive, something like 2.5V. No idea how long they stayed in that condition but I will assume the worst and that they probably won't come back, but I have to see for myself. At least as a scientific experiment, to see how a bad cells acts when charged. And how quickly it loses charge.
I got some Panasonic, Sony, LG and a few with no meaningful marks on them at all, other than some string of tiny numbers. I looked them up, the name brands were between 2400 - 2500 mAh, so not too bad.
I used to use AW's protected cells but now will keep them only for the 2x18650 configuration. I usually use 1x18650 these days, with Malkoff M60L and the neat thing is, you can see, visually, when the cell is discharged. I am pretty familiar with the lumens at regulation, above 3.7V and can instantly tell when it hits 3.5V and below. The lite is just noticeably dim.
I used Panasonic 2900 mAh cells, unprotected, for months, with excellent results, never overdischarging them.
To sum it up, in 1-cell lites can you unprotected 18650 cells if you pay attention to lumens.
2x18650 configurations with regulated modules like Malkoff M60 make this impossible. As the lite will still stay in regulation even when the cells are deeply discharged, say down to 2.5V each. The lumens will not be affected much in this case. So you discharge your cells way below safe limits without knowing it.
Of course maybe unregulated multi-cell lites can also use unprotected cells. I tried the P90 incan drop-in module with 2x18650 of these newly gotten cells and it got really dim when they discharged.
I use Pila IBC charger, but kind of want a 4-bay charger.
Some, I noticed, have gotten extremely hot to the touch while charging. They were at about 4.1V. Not sure what it means. Probably that they are not good. Or internal resistance?
I took the cells I charged, looked at them after 24 hours and most held charge. A few declined to 4.1V. One discharged to 1.5V, so it was clearly not good. I plan to check the voltage a week later.
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