Yesterday I’ve lost a light.
During some inspection work under the roof, a light fell about 8 meters and dropped on a stone.
What happened then was a bit scaring, The light bounced a bit and finally came to rest in the grass near the stone. Before I could reach there, it started to emit a crackling sound and suddenly it just burst, with the shards flying away. They have not yet been found, as the garden is quite naturally growing, no fire, as it’s all green and juicy.
I suspect it was the battery being crushed on the hard button contact during impact and blowing up after internal stuctures damaged…
Now some questions: Wouldn’t it be good to have some sort of venting valve or feature for such cases? Maybe even simply have some internal venting ways from the battery to the switch cover, which could just pop out and release the pressure safely?
How could the battery be protected from an impact?
Well, at first an argument pro lanyard, ok, next time.
Ahm, yeah. I do not want to shine a dubious light on a manufacturer/designer.
I guess only very few flashlights on the market actually have some sort of safety features.
Giving max impact height of one meter in the datasheet is not exactly a safety feature, as one meter can easily be exceeded with a light falling simply off the hand.
The battery size was the 21700 that came with the light. I do not remember the technical specs, It has been used a few minutes after fully charged.
Datasheets from the top level cell manufacturers do show an over pressure valve as a safety feature to vent before burst, no explosion and no fire.
In addition there can be over current and over temperature disconnect devices to open-circuit the cell in “Protected” cells.
Depends upon the quality of the cell.
But if the flashlight is sealed water tight such as IP67, then any vented gas from the cell would have no escape path and the flashlight would explode.
The light will vent with decent pressure from its switch and/or charge port becasue they are thin rubber.
But the light will likely explode like a grenade even if the tailcap was off if the battery is determined to explode at full power in all directions.
Interesting, flashlight explosions are a rare occurrence, there was a story of a modified maglite a number of years back which exploded and damaged a glass balcony - I believe the cause was cells of different types/voltages in series…
There was also a case of a 2 X CR123a light that exploded while a guy had it in his mouth causing him a huge amount of injury.
Occasionally there is talk of safety vents etc, I’ve never seen it implemented though.
A couple psi won’t make much difference.
In another thread someone mentioned that a flashlight fell into a lit BBQ and it exploded like there was no tomorrow.
I forget if they could even find the fragments.
>How could the battery be protected from an impact?
For some lights you can create&fit "donut" spacer rings made from soft material (o-ring, thick felt etc.) for both ends of the flash light to sort of wedge in the battery.
These have to be made fit precisely to not squish the battery or damage your flashlight.
The battery can't move (that much) anymore and is better protected against hard impacts.
Edit: springs on both ends are not enough to protect against hard impacts like an 8m drop. They will just be compressed flat and act the same as a solid at this point.
Flat top batteries were never designed to be used in flashlights. Some brands may have stronger top designs than others. Most springs are certainly going to lessen the impact to some degree. If we look at rewrapped batteries from some of the larger flashlight manufacturers that are available in retail outlets most do not use flat tops. Most add a button and a protection circuit. Armytek just recently got into the rerap 21700 game and they do use a flat top with the Wizard Pro Max but they also use a spring on the positive end. Of course size matters on some lights. I only have one light that uses a 21700 and it has a button /protection circuit and a spring. The two lights that I carry daily both use flat top 18650s. I don’t believe the Lumintop fw1a has a drop rating at all and it was sold without a battery. And I have dented some. The Armytek wizard C2 pro uses a spring and has a 10m drop rating. However armytek still sells some 18650 models without springs on the positive ends and still rates them at 10m. So these are on extreme ends of the spectrum. With 21700 batteries that’s a lot of extra weight. Again maybe some flat tops are stronger than others. On some lights size matters. Using button top batteries and springs adds length to a light.
Still haven’t found the pieces except for some glass shards near the stone.
Now I am more afraid of the lithium and other chmeicals of the battery in the garden. I’m going to borrow a metal detector and search for the pieces, hope that helps.
Any caustic reaction may have stopped by now, so I do not think there is fire hazard or similar.
Can the chemicals enter stable (non-poisonous) reaction products or do I now have to sieve the entire garden, until everything has been found?
This video may well be fake.
Who knows if the light on the stairs is really the light that has been thrown from the window?
It it really boiling water, or something else with a lower boiling point? Vaccum, low pressure?
How can a light that reaches 100°C in the boiling water, as is suggested in the video, still function without overheat protection turning it off?
I’d take videos like this with a grain of salt.
Edit: found Dichloromethane as a very common, not instantly flammable clear liquid that boils at less than 40°C
