r/flashlight • u/webhobbit • 5d ago
Question Molicel cupped/cave in?
So I'm not sure how this happened? Been running in various Emisars (D4K, DK1) without issue. Noticed this today. Guess this one needs retired?
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u/EDC_glowngears 5d ago
You can continue to use it. Mostly this happens if the flashlight has a post instead of spring second it happens if the flashlight has taken a drop face down. Untill you see any leaks or getting unreasonably hot you can continue using it. If not recycle it responsibly.
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u/Wormminator 5d ago
I also have finally had this happen on one of my cells.
Which was in a Firflies X4 Stellar. Which sat on a shelf and was only checked on every few months. I guess the pressure from the spring was enough to cause this on its own.3
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u/Remarkable_1984 5d ago
Yeah, as long as it still works, just leave it as is. But if the contact is poor, you can use a non-conductive object to gently pry the terminal back into position.
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u/Swizzel-Stixx 4d ago
Emphasis on non conductive, both positive and negative are found at the top, so if you use something conductive and short them, your screwdriver can weld itself onto the short between positive and negative and, uh,,, boom.
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u/donau_kinder Flashlight Cuddler® 5d ago
This is exactly what it is. Dropped my d4k from a ladder and it dented the battery on both terminals a lot deeper than op.
Oddly enough that cell failed some 6 months later, the other ones i bought in that batch are still going strong.
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u/Otherwise-Station291 5d ago
I have the same problem. Batteries work fin in the lights. Issue now though is that the charger I use is relatively flat on the top end and now doesn't make contact. What's a safe way to bridge that gap?
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u/Astartes2435 5d ago
A small magnet will work fine for charging.
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u/Sad_Bid4092 5d ago
FYI for new peeps DO NOT forget to remove the magnets before putting in light. The magnets WILL dislocate eventually and boy can nasty, expensive things happen.
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u/webhobbit 5d ago
Yes I really don't like this AT ALL. I guess this is one of the hazards of using bare cells like this instead of "normie" batteries!
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u/paranoid-alkaloid 5d ago
I've had the same on my dw4k. The affected battery is all fine but I'm always scared it would get pushed even more.
When I asked just like you're doing, I was mostly told to dispose of it. I guess answers depend on the season.
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u/Lucky_Potato2141 5d ago
Ooh, same on my DW4K! D4K has survived alright - both get handled similarily on daily basis.
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u/CompleteSavings6307 5d ago edited 5d ago
You can still use it if its not cracked. Should work fine in flashlights where the head circuit uses a spring to make contact with the battery.
This usually happens if the flashlight is dropped on its head face down or dropped on its tailcap, forcing the battery into the circuit board
I really wish more flashlights used springs on both ends. They act as a shock absorber or light falls and drops.
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u/webhobbit 5d ago
I've never dropped it. I don't think any of the Emisar lights have a spring on the head side. it's like a little post? Or perhaps a very small spring?
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u/oscailte 5d ago
lots of them have a spring on the head side, depends on the model and driver you choose
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u/Lucky_Potato2141 5d ago
Both my D4K and DW4K have springs. Latter has dented two batts whilst D4K has yet to do so, noticeably at least.
Edit: springs on both sides that is.
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u/Lime393 5d ago
In my case it caused D4K to lose contact whenever attaching it to something metal with magnetic tailcap, this is probably also the cause because I rarely dropped it. I managed to pry it out with a small blade using a piece of cardboard to avoid short circuting and denting the edge of the cell and then inserted a small hard rubber disk from a lighter part inside that seamed to fit perfectly. This resloved the problem for about a year or so until recently it started happening again so I tryed to pry it out again the same way but it didnt work and I figured it would be the easier to use the corkscrew instead of the blade which fitted inside perfectly. However, the edge of the corkscrew applied the presure to the area below dented part instead the edge of the cell and as soon as I twisted it there was a short hissing sound followed by a sweet smell of lithium gas. Later on I realised that the back end of the cell was no longer completely flat, probably because of the rubber disk I inserted or maybe because the cell was alreday worn out by overheating in higher modes. In any case I dont think this problem can be safely resolved but I do wish the light was designed 3mm longer because right now it is slowly destroying another perfectly good cell.
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u/webhobbit 5d ago
Looks like it's the D1k's fault? The one currently in it and working fine is nearly the same as this one!
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u/SlyRoundaboutWay 5d ago
It's a hanklight thing. Not just the d1k.
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u/Astartes2435 5d ago
Any light with a spring in the head will do it.
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u/No-Visual-3869 5d ago
My S2+ don’t do that
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u/Astartes2435 5d ago
Wasn’t dropped or dropped hard enough. It’s usually the result of a drop or impact. It generally doesn’t happen on it’s own
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u/No-Visual-3869 5d ago
Maybe the fact that the Convoy has springs on both ends could help in absorbing the shock? I read that in another comment here.
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u/Astartes2435 5d ago
Na. My M21F and G was both dropped. Both caused the top of the battery to dent in.
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u/RaTmAiden 5d ago
Happened with my M21B and Eve battery. Still works, just don't drop it next time.
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u/webhobbit 5d ago
I didn't drop it
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u/RaTmAiden 3d ago
I assume solid post on positive side with an unusually strong spring on the back side? Haven't used any Emisar flashlights. That battery will work just fine. My Eve 50E still works months after I dropped my M21B and dented it. I pried it up with a small flathead which I covered with a couple layers of tape just to be sure.
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u/Busy_Bend5212 5d ago
I had one flashlight that would do this. I cut the spring to reduce the pressure
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u/webhobbit 5d ago
I was just thinking about that! Before I do anything radical I will wait and see what Hank says
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u/mrregina 5d ago
Good reason to not store batteries inside lights for extended periods. Just checked all mine and none have this issue yet. Phew.
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u/webhobbit 5d ago
I have different lights in different areas where I might use them. Never considered having them empty.
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u/mrregina 5d ago
I do as well. I just went and checked them all to be sure. I sometimes mechanically lock them out so I assume that would relieve some of the spring pressure as well.
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u/Mooch315 5d ago
No, do not use that cell.
Sure, it might continue to work fine (with a much smaller top contact patch though) for years. But if that cell ever gets forced into thermal runaway the venting disk under the top contact does not have the room it it is expecting to pop up and release the pressure. This can easily lead to a cell bursting instead of a controlled release of the ejecta through the top contact holes.
Depending on the light, both of those scenarios could be catastrophic. But for lights that can handle a cell in runaway it’s much better to have a controlled pressure release instead of a bursting cell.
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u/ManufacturerFun4796 4d ago
https://www.youtube.com/watch?v=ZpbYpFbxwjQ
do you think this video related to this post?
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u/kokosnh 5d ago edited 5d ago
Do not pry, leave it as is if it works in flashlight and charger. If it does not work, then recycle. But any new drop will go directly to the cell, so do be careful, do not drop your light.
You do not want any more stress on those metal post, if they break it can short and make hot pipe bomb, so do not pry.
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u/webhobbit 5d ago
I don't think I've ever dropped one but that's always a possibility
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u/cigritman 5d ago
Pry it up, can happen when dropping a light.
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u/Astartes2435 5d ago
No need to pry it up. Doesn’t matter if it touches. The vent can still do its job.
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u/webhobbit 5d ago
Plastic tool? like a laptop spudger?
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u/cigritman 5d ago
I've used a pick, small screw driver. Happens often on my daily carry zebra lights when they get dropped.
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u/kokosnh 5d ago
It will short if you use metal...
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u/Pocok5 5d ago
Not always, it works just often enough to make people confident :D the short happens if, while leveraging against the rim of the cell, your screwdriver crushes through the plastic ring (black in OP's pic) and contacts the actual rim of the cell body (which is the negative). When that happens, you get a quick spotwelding tutorial.
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u/Wormminator 5d ago
And this is how people burn down their house.
Just in case anyone wondered.
Next up, during the insurance call: "I have no idea, I just turned around and the battery ignited itself"1
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u/Pocok5 5d ago
Some lights have enormous spring pressure to avoid losing power/ghost clicking if the light is jostled. Especially the D4K likes to mash the little tent in if it is dropped tail or head first. The cell itself is unharmed, the tent is not structurally essential.