Thank you again for the concern guys.
I know Im at fault for not carefully checking the batteries. I assumed that if there was something wrong that the seller knew about, he would have informed me. I was caught up in the excitement of having one of the strongest lights and I just wanted to light up the night... a very very expensive lesson. Honestly though, I never knew it was this dangerous. Had I read anything like this on the forum, I would have been way more careful. Hopefully, Im the last in the CPF family that this happens to.
Just saw this thread. This is likely the most dramatic reminder to date on battery safety, the preparation and learning that should take place by lithium battery users, and the importance of adequate planning/forethought of possible safety issues by modders/sellers. Despite best of intentions, accidents and problems will still occur from a myriad of sources. Hopefully, like this thread they can be used to learn from.
dcaprilia, first and foremost, it is great that you did not sustain serious injuries, and have recently learned that your insurance coverage is excellent. Secondly, it is truly amazing how well you have handled this situation and how you contributed the facts for the benefit of the community, given what you went through. Seriously, I would nominate you for CPF Member of the Year if there was such a category.
It appears that most of the salient, causative factors, reasonable speculations, and lessons learned have already been done. It is obvious that secondary to improper cell condition/use, there was a cell(s) reversal, multiple cell short, venting within a closed pipe, followed by a catastrophic pressure buildup and explosive release at tube section joint, with enough force to strip off those threads and do all the subsequent damage.
This is also not the only "Elephant" (4 wide 18650) style light that had issues with shorts developing. You are on the bleeding edge with such high power lights here, but that should not be taken literally (poor attempt at humor).
LiMn cells are safer than LiCo cells in that it takes a higher temperature to bring them to thermal runaway, and a higher overcharge voltage before they rapidly vent (sometimes with flame). They are safer, but not "safe" in the absolute sense of the word.
While they can endure more abuse, they can still rapidly vent, sometimes with flame.
LiFePo cells are safer yet. They can take even more abuse and only seem to vent, rather than "vent with flame." However, a rapid vent is still very close to an explosion.
Tom
A year and a half ago, when I wrote about
various lithium ion categories here, and did my
testing of various Lithium Ion 18650 cells here, I spent quite a bit of time researching all that I could find.
I was careful to put the categories of "Safe" Lithium Ion chemistries in quotes, as there was not enough clear cut information since they were so new. As Tom has said, "Safe" chemistries is relative.
These new "Safe" chemistries were mainly being developed to address and fix the
Lithium Cobalt Ion runaway 1300°F fires and toxic fumes that were being seen with computer laptop batteries, leading to devastating fires, and
tens of millions being recalled. There was also a need for safe, high energy batteries for power tools and electric car designs.
I think it is quite noteworthy despite the explosive venting of gases, that these Sony Konion cells did not in fact lead to a runaway 1300°F fire in this case. The flashlight tube's aluminum is not melted, and recovered battery shells still have green color label visible. So in that regards, these cells are safer than Lithium Cobalt.
I could not find out if the vented gases from Lithium Manganese (Emoli), Lithium Nickel Cobalt Manganese (Sony/Konion) and Lithium Iron Phosphate had the same
ultra-toxic hydrofluoric acid that Chrontius mentions--seen in Lithium Cobalt cells.
I also did not find evidence at the time I posted those threads 18 months ago that the "Safe" Lithium chemistries had the potential of venting with flame, nor leading to the 1300°F fire causing the cascading thermal runaway spreading to all other cells like you see with "unsafe" Lithium Cobalt cells.
Perhaps more testing and documentation has come available since then.
Tom, do you have a source that documents the specific issue of high temp flames scenario with Lithium Manganese--would be good to read and update old threads?
Certainly the Lithium Iron Phosphate have had the best safety track record thus far.
