@Jumpman I’ve never heard that pressure valve can open because of vibrations, and it’s hard to believe considering its construction… What is remaining excessive pressure. Still not clear if overcurrent triggered it or Samsung 25r are just prone to such failure, or it has something to do with ageing as well.
My “killing” tests on 30q never revealed such a weakness…
Great mystery. The gov vib test for airlines I’m guessing isn’t going to well represent what happens on a board but tells of different directions tested and the details of testing. what do these numbers of amplitude and frequency equate to or what would be on a typical board?
“(1) Vibration test. The battery must be rigidly clamped to the platform of a vi- bration machine, and a simple har- monic motion having an amplitude of 0.8 mm (0.03 inches) with a 1.6 mm (0.063 inches) maximum total excursion must be applied. The frequency must be varied at the rate of 1 Hz/min be- tween the limits of 10 Hz to 55 Hz. The entire range of frequencies and return must be traversed in 95 ± 5 minutes for each mounting position (direction of vibrator) of the battery. The battery must be tested in three mutually per- pendicular positions (to include testing with fill openings and vents, if any, in an inverted position) for equal time pe- riods.” -https://www.govinfo.gov/content/pkg/CFR-2010-title49-vol2/pdf/CFR-2010-title49-vol2-sec173-159.pdf
Im too cheap to ever know beyond the headlines but vibration could be a possible cause of failure But to have multiple p groups fail…and these https://www.sciencedirect.com/science/article/abs/pii/S0378775315007648?via%3Dihub “ Post mortem analyses and μCT revealed a loose mandrel for the tested 18650 cells.
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Depending on the direction of motion, the loose mandrel caused serious damage.”
I’m confused about the pressure relief value; are you saying it once was an open circuit and now showing a voltage again? I thought when they popped I’d see open circuit permanently and no going back unless u maybe too off the device. I have no idea and don’t recommend doing that just wondering about how they work
@Hummie you always manage to find some interesting articles 
But actually there is a nice point about orientation, since indeed I would expect more damage if cells are in vertical position. Which is not the case for boards btw.
you understand correctly - valve is not going back until you press on it (see picture above). Pity that with nickel strips welded there is no enough room to reach the valve, so I needed to tear strips off 