Ahhh.... yes. Was it one of those red high discharge rate batteries? Those suckers are capable of providing a whopping 6C (or maybe 10C?) of continious current. whoo hoo! That's something like
10 Amps for 8 or 10 minutes. I'm guessing it didn't have anything to do with the battery malfunctioning (shorting internally), more likely it was the connector on the atty/carto shorting, or an adapter if you were using one, or the positive cap on the battery came in contact with the side of the battery tube because the casing/insulation was damaged. Of course if it was shorted for long enough to melt the spring then I suppose the battery could possibly have sustained some damage.
I'm not a huge fan of those batteries since they are not electrically protected. Lol, your system IS sort of mechanically protected (as you saw) in that the battery is capable of producing plenty enough current to melt the spring. Spring collapses and the battery loses contact with one end or the other
. Actually that's probably a lot safer than a smaller discharge rate, unprotected battery. With the high discharge rate you "blow the fuse" by melting the spring. With a smaller discharge rate it's probably not going to melt the spring in a short amount of time and the body of the PV and, especially the battery, are going to get a lot hotter. Even with the "safe" chemistry batteries there will still be some venting and very hot goo being expelled (although no real explosion or flames).
Congrats. All the component specs said that's what should happen in theory... and now you've demonstrated it in practice
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