Good Quality 26650 Cells

I recently purchased a dive canister light from eBay. It's a decent quality build but I'm having problems with it which I suspect are battery related.

The light unfortunately is a 3S configuration. his drives XML-U2. I haven't been able to measure the current yet. It has a pushbutton on the canister that cycles between 100%, 50% and off.

The problem, using the original blue TrustFire protected cells that came with it, is that between 2-3 minutes (sometimes more, sometimes less ) it auto down switches from 100% to 50%. Then a few minutes later it'll turn off. Sometimes it'll run on 50% without ever seeming to switch off.

I bought a set of UltraFire protected cells because the light was advertised as unprotected cells. The light behaves better with these batteries installed but it still flickers a little and doesn't seem to be at quiet 100% the entire time.

I don't have any batt diagnostic equipment. How should I go about solving this? Is there a known good quality 26650 cell? Do I need to do a deeper dive?

Very much doubt it is your cells causing auto down unless they are really bad.
A single XML driven around 3 amps, with fully charged cells, current draw will be less than 1 AMP draw if using 3 cells in series.
As cells deplete, depending on driver efficiency and light resistance, draw will still be not much higher than 1 AMP.
That's very low current for 26650 or 18650. Even a decent RCR123 should be able to handle that without problems.

The vendor claims the draw is 2.5amp (unverified). I now have 12 26650 cells to play with (Blue and Red TrustFire/UltraFire/No Name) and I found another set that also did the auto drawdown. Another set did not do this and stayed at full power for a very long time. I actually ran it all night long until it was very dim and it took two taps off the button (->50%->Off) to turn off so I'm very happy with these.

Another set also worked but the light became very tap sensitive. If I rapped the battery canister the light would flicker and if I hit I harder it would shut off. With my other set of batteries it does not do this.

So I guess I just have to find the right batteries?

I'll admit my knowledge of LiIon batteries is minimal..... that said I found 3 batteries that work well. I have 9 other batteries that were suspect. I fully charged all 12 batteries and then using 2 of the good 3 batteries I tested with each of the 9 suspect batteries 1 at a time. In all 9 tests the light auto down after 1-3 minutes. When I went back to the 3 known good it was fine again.

Very odd..... so I think I have 3 good batteries that will give me a few hour worth of diving. That should be fine or 2 1+ hour dives a day. But I don't know how to be successful in finding three more cells for a second set. Maybe I should just look for Panasonic 18650 cells with sleeves?

All cells with xxxfire are crap ans may be dangerous.
High quality cells are Keeppower, Enerpower, Xtar, Efest, 4sevens, Tensai.

Do a search, there are more than enough topics about 26650 cells.

I have kinoko 26650 which vinh recommends,i get 9.6A on the x3vn 3300lm


MNKE are rated at 30A max


Also if want protected 26650 cells then xtars come out well:thumbsup:

king kong too,have a read here for ideas
http://www.candlepowerforums.com/vb/showthread.php?379813-Best-26650-for-VN-Lights

:thumbsup:

Bear in mind thats for a specific light,so obv results vary,but will give an idea of 26650 options either way

Yes the thrust fires are generally crap, but the flame ones are quite OK.

But I do not think the problem here lies with the cells. You say dive canister? Is it plastic or metal? Does it get raging hot? Those lights are meant to be use under water to dissipate heat. If it is plastic, you are out of luck I think, the light is than as crap as the batteries you bought . Plastic lights are always low powered for a reason: the can not get rid of heat .

Epsilon said:

Plastic lights are always low powered for a reason: the can not get rid of heat .

Click to expand...

They melt the heat away :laughing:

I totally understand the light would be suspect. And it still is.... after all it's cheap Chinese made found on eBay. That said, I have a set of 4 TrustFires (also cheap eBay) and the odd thing is when I use 3 of the 4 all seems stable and the light runs for a couple hours no problem. However if I replace one of those 3 batteries with the 4th battery from that purchase the light behaves badly and turns down within a couple minutes.

I didn't want this to get booted to the lights forum so I only mentioned it was 3P 26650 driving a single XM-L U2. The light is metal and it doesn't get very hot. The bad behavior was also observed in 70f water. ( I wanted to do a nice easy checkout dive in the Comal River which is blue with 25' visibility spring fed and relatively warm before taking it to 130' in 5' vis 0 ambient light and 50f water temps! )

So I have a weird observation. 2 of my 3 cells measure about 4.11v. 1 of my 3 cells measures nearly 0. On the 200mv scale it measure 1.0. The odd part is that when I put the three cells together in series the light works fine. Do protected cells pass current when they are bad?

I will get to the point here,get some decent cells,trustfire(in general do not fall in that category).

For a decent 26650 i am sure it was under $20,as for light it will just bring down the other cells,if meant to run on 3 and using 2 its more strain on the cells,some lights you loose max,cheaper probably just run on..........

Sorry to be blunt,but advice on poor,unsure QC is difficult,mkne/kinoko/king kong/xtar to name 4 good 26650 cells,in short(no pun intended) you get what you pay for.I actually have some fire cells,ones with fire on,they have been fine,so i guess its a 50/50

Spend a bit more,get it right 1st time imho.

Good chance the mah rating is plucked from the sky too.............mkne are good cells,well priced as are xtar...............get 3 of them and take from there.

Dont know much on the light,if its cheap its been made cheap,not something you want failing on you in working conditions,xtar make some well priced diving lights,d06 to name 1 18650 size though

Blunt is wonderful. I just haven't had a chance to source more yet. I'm thinking I'll go with 618650 cells and sleeves as it seems easier and cheaper to get good quality protected cells that way. 2600 x 3 is more then enough for my longest dive and I'll just switch out cells between dives.

chrpai said:

Blunt is wonderful. I just haven't had a chance to source more yet. I'm thinking I'll go with 618650 cells and sleeves as it seems easier and cheaper to get good quality protected cells that way. 2600 x 3 is more then enough for my longest dive and I'll just switch out cells between dives.

Click to expand...

:thumbsup: just read up on here,charging/safety side,also make sure if protected fit light,try and stick with known makes,not chinese cheap ebay ones.

Ideally protected cells if using 3+

Have a read up,keeppower,panasonic,orbtronic,xtar,lots more,just make sure reputable seller and good cells,decent charger,dont cost the earch.Under $40 for 4 decent 3400mah protected cells,around $20-$30 for a decent charger...............job done and will last years if top cells off(after use just charge up again,without running tight down)

BTW I think I finally have perspective on my real problem. I think the dive light is defective. I think that when I give it the 3 fully charged LiIon cells it's just too much to handle and it switches down. When I put in the cell that "works" (the one that's actually putting out 0 volts but still allowing current through ) the voltage is much lower and the dive light is ok.


Still, it seems to run real bright for 2 hours on the remaining 2 cells actually putting out juice. I'll just live with it.

Have you tried using 2 26650's and a spacer? might solve (sorta) your problem.... sounds like the driver is only rated to 8/10v max, and it sulks (strobing prob) when you put 12.6 through.

how about some pics?
the root of this issue is likely the crapfire batts.
in series?:fail::eeksign:
paralell safer.