New cheap 26650 diving light at DX

Welcome to BLF flydiver! Looking forward to hearing how that light performs on a dive.

Couple questions since I’m new at LED mods.
How would I do this?: [Emitter to pill thermal path is weak (small mod would make it much better)]

I did not take the lens off. Is there an O-ring under that? Pictures don’t show well there.

Tail stand? It’s supposed to be a dive light, at least that’s the way I interpret it. It has a retainer loop on the tail that is critical for diving. I don’t see that as a con for this light.

Welcome to BLF flydiver! You'll love being here! :)

Rinsing is always a good idea, but I wouldn't be too worried. The switch is magnetic and there are no other mechanical parts than the metallic spring and small pellet (which are used to lock the switch to on / off positions). I would add some vaseline to the spring. Those parts will rust anyways, but I bet they'll last quite a long time. The spring is easy to replace if needed, but the pellet is very small.. So small that I lost it already. (Be careful when disassembling! The pellet is shot off as soon as the ring is taken away!) Not sure where to find a replacement..

See photos below.

Magnet side of the switch. Magnet is located in the plastic ring, body has a groove allowing it to move to on & strobe positions:

Hole & spring. Pellet should be on top of the spring.. (note also the notches in the plastic ring):

This light has basically a dreaded hollow pill, see below (reflector & pill assembly opened from middle seam):

The mod would be simply filling the hollow part with copper (or similar). For example couple of suitably sized coins would do. Idea is to have some metal under the emitter star and touching the sides of the pill, allowing the heat to escape from the emitter.

[quote=flydiver] I did not take the lens off. Is there an O-ring under that? Pictures don't show well there. [/quote]

Yes. There is a thick O-ring, sitting on a ridge, partially glued in to keep it's position. The lens presses that down so that it will tighten between body, reflector, and lens, sealing the head well. You could apply some silicone when opening the head for modding.

The O-ring can be seen well in this photo:


[quote=flydiver] Tail stand? It's supposed to be a dive light, at least that's the way I interpret it. It has a retainer loop on the tail that is critical for diving. I don't see that as a con for this light. [/quote]

I fully agree, but this light is so affordable that it will be bought also by non-diving purposes. So I thought it's good to mention that.. And of course there might be a situation where you come from a dive, go to your cabin, and electricity goes off -> tail standing light would be useful then. ;)

Unexpected and painful

That pill is a bummer. :expressionless:
Everything else looks good too.

Thank you for the great pictures and explanations. My level of understanding just took a notch up.
I’ve got other lights so using this above water is not an issue. Obviously I have some great cooling in NW water but I gather the path from the emitter to the sides isolates it so even though I’m cooling the body, the emitter may not be getting cooled properly. Hmm. That could fry it over time?
Is that unit simply pried apart? Can’t be a screw because of the wires.
I’m used to using PC thermal paste, but that won’t hold things in place I would guess. For this mod do you get some kind of thermal glue?

In my Underwater Kinetics SL3 the emitter has a direct track to a sleeve the length of the light to help cool it. The whole exterior unit is plastic so that compromises the transfer a bit. The SL3 kind of my standard for this kind of light. The SL3 is a very good NW backup light or main tropical light. UK has excellent customer service. For diving good customer service is very nice indeed. I’ve been through 3 of them, none my fault, and they’ve replace them all. I’m sure that exchange is now negative $$ for them.

Note-sorry you lost part of the switch taking it apart to show me. Should I venture to do that I’ll keep it in a plastic bag. May I suggest getting some silicone grease from a scuba shop instead of Vaseline for assembly. I think Vaseline is petroleum based. Though this has silicone O-rings they are often neoprene (petroleum based) in dive gear > like dissolves like, so we avoid petroleum products. Regulators are breathing life support with lots of O-rings in them so we avoid petroleum for that reason too. You really don’t want to be inhaling that kind of stuff.

No problem. Glad if I could help.

[quote=flydiver] I've got other lights so using this above water is not an issue. Obviously I have some great cooling in NW water but I gather the path from the emitter to the sides isolates it so even though I'm cooling the body, the emitter may not be getting cooled properly. Hmm. That could fry it over time? [/quote]

Yes. That's exactly why hollow pills are evil, and why I'm planning to mod my light.

[quote=flydiver] Is that unit simply pried apart? Can't be a screw because of the wires. [/quote]

It is a screw. Wires can be kept straight if you loosen the driver first (it is held by a retaining ring, see below)

[quote=flydiver] I'm used to using PC thermal paste, but that won't hold things in place I would guess. For this mod do you get some kind of thermal glue? [/quote]

I thought of taking the driver off and simply soldering a chunk of metal to the pill (= lower section of the assembly)

[quote=flydiver] Note-sorry you lost part of the switch taking it apart to show me. [/quote]

Not your fault. I did it before you even asked. :) Just a bad habit taking all my flashlights apart and taking photos. ;)

[quote=flydiver] May I suggest getting some silicone grease from a scuba shop instead of Vaseline for assembly. I think Vaseline is petroleum based. Though this has silicone O-rings they are often neoprene (petroleum based) in dive gear > like dissolves like, so we avoid petroleum products. Regulators are breathing life support with lots of O-rings in them so we avoid petroleum for that reason too. You really don't want to be inhaling that kind of stuff. [/quote]

Good point. I actually use silicone grease for flashlight threads, but I thought that vaseline would better keep the rust away from the spring.

My preference would still be silicone, especially for O-ring, but I use it on threads too.
I use ‘grease’ for bearings.
Can’t say I use Vaseline for anything. Probably got some way in the back of the medicine cabinet about 20 years old.

Useful picture for getting inside the unit.

I had this light a while back, it was ok but didn’t like it enough to keep it. I gifted to a buddy at work.

Here's how I modded this light.

The inner diameter of the upper part of the pill matches 5 Euro Cent coin pretty well, so I don't need to go to hardware store.. ;)

However, stacking coins on top of the existing ridge would make the emitter to sit too high => some work was needed.

First I dremeled some aluminum off:

Then continued with dremel and made holes for leads:

Then, again with dremel, smoothened the coins:

The bottom wasn't exactly leveled, so I added some desoldering braid and solder to straighten the coins:

Finished pill from above:

Add some Fujik, emitter, and solder leads:

Done. Much better thermal transfer.

While doing this I figured that a blob of solder could work as replacement for the lost pellet. And it did! So the light is again fully functional. :)

Of course the emitter in the last picture was there only for presentation purposes.. :)

Now the light has XM-L2 T6 3C emitter on SinkPAD, resulting nice NW tint and about 800lm OTF (after 30s, of course). I'm happy!

great job and shots :slight_smile:
I ordered 1 too with the 5$ GC, the heat dissipation looks poor the 5 cent coin is copper only externally, inside as you can see sanding is steel, that will not help thermal dissipation right?

Ever wondered how is the thermal conductivity of the nordic gold, (10, 20, 50 cents) is 89% Al and 5% Copper 5%zn and 1% stain so in the paper should be good but how in fact mixing and shaking all? anyone know that?

Btw destroy the money is illegal XD

I didn't know that 5 euro cent coins are not copper before sanding them, but decided to continue because steel is still 2000x better than air. ;) (and "only" 4x worse than aluminum / 7x worse than copper)

[quote=MixoMaxo] Btw destroy the money is illegal XD [/quote]

Not in Finland :evil:

Thanks for the review! Is it possible to operate the control ring with one hand - critical for me underwater?

Welcome to BLF!

Yes, it's not only possible, but also easy. I'm starting to like this light a lot, especially after the mod. :)

Thank you very much for welcoming and your answer. This flashlight is cheaper than money - looks like the best deal in town. Will be acquiring it shortly along with a 26650 battery. Which one would you recommend? My usage pattern would be turning it on only on occasion underwater - looking into caves while spearfishing. 10 minutes a day at most. So one battery can last me for at least two weeks without a need of a charger.

Thanks in advance!

I have been using protected Trustfire "5000mAh" flames (about 4000mAh real) and unprotected King Kong 4200mAh cells. Both of them are good.

Unprotected cells are usually better for diving (they don't shut down suddenly when running low on power, just dim slowly), but as you are just looking into caves, that shouldn't matter so much.. And protected ones are safer! You can't ruin the cell by overdischarge and protection helps in case of short circuit (or overcharge caused by faulty charger).

Those Trustfires can be bought also from DX (about $2 more expensive than FT, but if you want them to the same package..)

Excellent, thank you! I assume this flashlight can take a protected 26650 battery (size-wise)

No problem!

Yes, protected 26650 fits well.

In that ‘TrustFire’ link you gave me there are two options: red ones unprotected and black ones - protected. Red ones have three reviews, black ones - none. I did some search and some say that the red ones are protected, but it does not say it on the battery. On the black one it does. I assume you are using the red ones. Are you sure they are protected?

I use these:

..and they are protected. It is also said on the cell: "...with PCB", see here: