So the real question is, what makes a light reliable or indestructable? It isn’t simply potting. the electrical components have to be high quality, capable of running the light at it’s design specs for a lifetime. Potting is good for a weapon mounted light, not so much any other reason.
Case in point, Eagle Eye built an X6 for cheap monies with a military grade type III hard coat. Super tough relatively small light. While everybody else was drop testing it and driving over it I tossed it out the window of a car going 60 mph. The light got a slight few scrapes but was comparatively undamaged, the only real damage was that a couple of the impacts (I video’ed it) collapsed the springs so the light quit working. I replaced the springs and the light is good to this day (years later) Now , had it been potted it likely would not have been possible to replace the spring on the driver and the light would have been trash.
I’ve modded potted Army Tek lights too, they even stole my pictures because they had never seen inside their own light! Designed in Canada, made in China… they warranty by throwing away defective lights and replacing them.
So that, ultimately, is what potting does for a light… makes it gun proof and trash ready.
Oh, I’ve potted my own builds before, and I’ve cut through a driver on the lathe to get back inside and rebuild it. Manufacturers like to pot as a warranty measure, lock it in so people can’t mess with or copy their design, and for that I can hardly blame them.
Good gun mount potting is NOT silicone, normally those have a black epoxy that is hard as a rock. You just aren’t gettin in that one and have the driver remain intact. And for this flooding of epoxy, well, normally it comes at a price…
Thanks for the post DB! Definitely a lot of good food for thought there.
I’ve had many lights fail over the years after seemingly trivial impacts or for no discernable reason at all (to me anyway). This had led me to question the durability of flashlights and to baby the ones I have now as a result.
Maybe potting isn’t as straightforward a solution as I thought, but I’m also not immediately convinced that it’s really only warranted for weapon-mounted lights either.
The prospect of manufacturers making more inexpensive spare parts available is a positive and another possible point against potting, but at the end of the day I’m interested in what it takes to make an affordable light that won’t break in the first place.
And yeah, I could “afford” to buy more expensive lights with a good warranty or whatever, but there are other reasons I don’t really want to go over ~$30-40 on a light in general these days. In the meantime I’ll start researching the most durable budget lights.
This what got me potting a few lights. I’ve also found another reason, it’s water proofing and to some degree strengthening perpendicular board-to-board connection. I picked up a few Mateminco TK01 lights. A great and over looked light in my limited opinion. It’s got one glaring weakness. It’s charging port is too open. Meaning a gap around the Micro-USB leading right inside. I potted one for the pool test with the port cover off. After two days at 7 feet it came up dry inside.
Related to previously asked questions, but what kills a flashlight when it’s dropped? I assume it’s just components coming loose from the impact, right? I think I read somewhere that linear 7135 based drivers tend to be more durable for that reason, because all of the components are fairly low profile.
My S2+ lights get dropped all the time, like all-year-round. So far, nothing has ever happened to them? The cells look a bit dented, but that will buff out
Lights are fine.
So what would potting bring in addition to the regular protection? Higher drops? break-resistant lens? different solder?
DBs post was excellent and gave me details I needed.
You need to restrict the movement of the battery from impacting the driver spring, which when bottomed out (coil bind) impacts the driver, Potting also aids in thermal transfer if you use the right stuff.
Not really…. battery/cell stops in the battery tube, a shoulder restricting the cell from going too far forward on impact/recoil…usually a shoulder with an o-ring to eliminate abrasions to the cell wrapper.
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. Even a bumper on the tail cap….limits movement allowing the spring(s) to maintain contact
It is easy to do with the Surefire lights because they are all mostly CR123 powered and have to be bored for the 18650/350 cells, even my 6P mods can be weapon mounted, I machined a battery stop into the battery tube on the head end.
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. Then polish the battery tube for a tight slip fit for certain cells like the VTC5A’s I use.
. Came up with a quick change module system fully potted driver, copper sink and reflector, the whole head is thermally potted and can be changed out from 2 different battery tubes depending on what emitter head I want to run.
Usually the batteries will get damaged. I have a few batteries with dents from lights falling hard enough to break the lens and smash the flat top in from the spring bottoming out. Restrict the battery movement = less damage.
The problem with springs is that not all of them are made equal.
Steel wire springs are good springs, but they don’t absorb a lot of energy on impact, meaning the cell has to absorb a lot of kinectic energy from impact.
BeCu springs are different since they take much more force to compress, depending on wire thickness and the number of coils, along with top diameter to bottom diameter ratio.
A large thick 1mm BeCu wire spring will take beating like a champ. A smaller 0,5-0,7mm BeCu spring will protect the cell, but might collapse.
I agree with what you have said. I have my first 2 Malkoff lights arriving tomorrow, and I ordered the battery bumper kits for both lights, and of course they are potted. I understand these are not budget lights, but it isn’t expensive to add a couple o rings to the front and back of the light. Then if you have a solid built light and you pot it, your good to go. Just as long as your not looking to mod it.
Malkoff’s are double thermally potted and done very well, a copper shelf, potting, driver with brass battery contact/sink, potting, spring. Heavy duty to say the least.
1. Battery stop
Initially the spring compresses, transferring some impact energy to MCPCB. Then there’s stop which quickly transfers the rest of impact energy directly to the body.
2. Stiff battery
All the energy is transferred to MCPCB but unless the spring bottoms out - the transfer is much smoother and peak forces much lower.
BlueSwordM, did you try to bottom out with protected cells? That should be easier to do.
Big force on the driver will make it crack. A little smaller - will make it bend. Repeated bending will make it crack eventually.
Intuition tells me that both long stiff battery and a stop should work well enough. Note at the tail cap there’s a similar issue. Though I think it’s easier to support the tail PCB with the tailcap wall, at least in lights that don’t have tail switches.
But that’s not all of it.
F.e. this light died due to a sideways impact. Managing battery impact wouldn’t help.
This may be related to
But there’s also another thing making me think this is not a full picture. DB Custom’s EE X6 experiments. A spring collapsed there so it was not very stiff and there was nothing that would prevent it bottoming out. Yet the driver (as well as the tailcap) survived despite being directly hit with a cell multiple times.
