Thrunite TN36 issues

My TN36 worked fine the first weekend I went camping. Now for someone reason it will not work on turbo mode. It is on for a split second, then off.

I have a feeling this is the light's built-in protection for undervoltage. All batteries are measuring 4.01 to 4.05 volts. Maybe this isn't enough. Maybe it requires 4.20 volts, and the batteries had enough juice when new, but not after a recharge? But I'm just now learning all this stuff as I do research.

Batteries are Thrunite 3400MAH. The label says "integrated battery overcharge/discharge protection circuits". I think this means it's an ICR (cobalt) battery because IMR do not use/need protection. If I understand correctly, IMR (manganese) batteries have higher discharge rate capability.

Is my 7300 lumen light right on the verge of being too much for ICR batteries? Will switching to IMR fix my problem?

Or maybe I shouldn't be suggesting a solution, because I don't know what the solution is. Maybe there is an actual issue with the light. But I'm suspecting it's the batteries.

What do you pros think?

I do think IMR or INR cells would make a difference . Maybe one of your cells is weak, at around 4v under load the voltage will drop, probably under 3.6v which is causing the step down. With higher drain cells the sag is not as much so can sustain higher outputs for longer. Samsung 30Q /25R or the 10a 3500 LG/Sanyo cells would be my choice.

Think the voltage is to low, to maintain that Turbo level. I use Samsung 25R's in mine.

Thanks for the replies. I will take a look at the cells mentioned and order some new ones. For the record, here is the reply from Thrunite:

3.6v 18650 can be charged to 4.2v. like 1.5v AA can be charged to 3.0v


TN36 is such a powerful flashlight that the electric current has to reach to 5 A (also reach 4.2 volts)to support turbo and strobe mode.

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Dont know how a 1.5v can be charged to 3v !! 3.6v is the nominal voltage of a 4.2v cell, so they should be charged to 4.2v for 100% . However when in turbo, the 4.2v cell might be 3.8v after sag as an example(dont know and not tested so a guess). Once the voltage drops bellow 4v, the v will be lower under load(under 3.6v as an example).

Either way there are more suitable cells and these i am sure will solve the issues with short turbo mode.

ven said:

I do think IMR or INR cells would make a difference . Maybe one of your cells is weak, at around 4v under load the voltage will drop, probably under 3.6v which is causing the step down. With higher drain cells the sag is not as much so can sustain higher outputs for longer. Samsung 30Q /25R or the 10a 3500 LG/Sanyo cells would be my choice.

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Are these the 3 you're talking about?

http://www.rtdvapor.com/samsung-inr18650-30q-3000mah/
http://www.rtdvapor.com/samsung-inr18650-25r-2500mah-green/
http://www.rtdvapor.com/lg-18650-mj1-3500mah/

What's the difference and what do we know about their chemistry? Any disadvantage to the 3500mah cells? All else being equal, they would last longer on a charge right?

Also, regarding my Thrunite 3400 batteries, since they worked when new, I'm wondering if there's a better way to charge or condition them. I use a Nitecore i4 charger.

FWIW.

I had this light using 4 X 18650, 3400mAh KeepPower protected cells. With those batteries I had no problem using Turbo at any point above 3.60V.

I returned it because of the HEAT,Not the inability to sustain turbo!

My TN36UT had this behaviour when I first used it with TN 3400mAh cells. My tests were compounded by a "charger" that gave up at 3.7V, so its idea of "fully charged" didn't do much. I've had it working well with higher current (and lower capacity) cells from various manufacturers. I'll experiment again with the ThruNite cells now they've hit 4.2V and see what happens and how fast they give up. I believe some of the online reviewers had been using these cells and run the flashlight on turbo for an extended period, so I'd recently switched from blaming the cells to blaming the charger. (With my other cells, it'll stay on - presumably throttled - turbo until the cells hit nearly 3V, although it gets toasty warm even with a fan on it. My MM15MB steps down to "high". Both cut out completely with under-charged cells. Alarmingly, my newer - also Nitecore i4 - charger thinks some of the Thrunite cells had dropped to nearly 2.8V during my experiments, despite the cut-out; I suspect the cells started unequally charged, due to my dodgy charger, and this confused the cut-out.) When off or at low brightness, the both flashlights thought the cells had charge (which is why I didn't check my charger sooner).

I'd expect you to be okay at 4V, but I'll report back when I've tried my cells. LGs, Panasonics, Samsungs and Efest were all fine if you have doubts. There's a bit more in my "High power flooders - postmortem" thread if it helps.

The heat is a problem, although at least the throttling isn't as bad as the MM15MB (I can't keep that from throttling even sitting right in front of a fan - insufficient fins, I suspect). As I've said before, I'd love someone to give up on waterproofing and make one with a CPU fan impeller sitting on the back of the LED heat sink block, pulling air in through the cell holder.

Good luck.

GrandPixel said:

Are these the 3 you're talking about?

http://www.rtdvapor.com/samsung-inr18650-30q-3000mah/
http://www.rtdvapor.com/samsung-inr18650-25r-2500mah-green/
http://www.rtdvapor.com/lg-18650-mj1-3500mah/

What's the difference and what do we know about their chemistry? Any disadvantage to the 3500mah cells? All else being equal, they would last longer on a charge right?

Also, regarding my Thrunite 3400 batteries, since they worked when new, I'm wondering if there's a better way to charge or condition them. I use a Nitecore i4 charger.

Click to expand...

Yes those are the 3 examples which are all good cells. The 3500mah do offer more run time potential if the application is not "too" high drain. The 3500mah will suffer more voltage sag than the other 2 cells. Imo the 30Q offer a good happy medium at 15a and 3000mah. The cells are "hybrid" which is a combination of chemical/s. The manufactures specs will tell you the chemistry ie:
http://www.nkon.nl/sk/k/30q.pdf

The thrunite being 3400mah will be panasonic B inside which are good for 4-5a off the top of my head. Fully charged they will offer turbo but for not as long as the 30Q or 25R cells due to sag under load.

Charge them up and check voltage when terminated, will get an idea then if the charger is actually fully charging them or not. The i4 is quite a slow charger at .375a per cell, i would look at a 4 bay charger that can do 1a across all bays(opus bt c3100 v2.2 is a good do it all charger and well priced as an example). This will also give you a rough idea of the cell V when putting the cell on charge and termination. The charger will allow you to refresh the cell too which is handy.

According to Thrunite, the TN36 uses 5A, not 10A or 15A or 20A+ that some of these cells provide. But you're saying the light cuts off because of voltage sag while under load.

Let's say the batteries are supplying sufficient voltage and "turbo" is working. In general, will voltage drop steadily as you discharge a set of batteries? Or will it remain at close to 4.2V until close to running out of juice? Which batteries are best in this regard?

Sorry if my questions don't really make sense. I'm trying to get a proper frame of mind regarding how different batteries will work in my light. This is all new to me.

I think some of the batteries are not OK (too low voltage under load). Exactly the same effect I had with Fenix FD40 -- it immediately fell back at attempt to enter turbo mode. But my situation was much more simple: the only 26650 was flat (3.2V).

I either use 10a 3500 cells or 30Q in my tn36vn which is around 8300 out the front lumens. No issues with turbo at all...

Just reporting back, now my Thrunite 3400mAh cells are charged to 4.2V. They don't run the TN36UT on turbo - it wasn't my charger. I assume the cells' protection circuit is tripping (there's a brief flash, then nothing). Since I saw the same behaviour with my MM15MB before, I imagine the same applies there. They'll run the TN36UT on high, no problem. so I've no idea how people have been reviewing the TN36UT with these Thrunite cells - I swear I've seen at least one review that managed it.

The same cells will run a TN30 on turbo, having checked (at least, it worked when I tried it, with no sign of cutting out). Obviously that's nothing like the same light output - IIRC, around 4000 lumens instead of ~7000, and with more of a hot spot. Turbo on the TN30 is more output than the high mode on the TN36UT, though - but IIRC reviewers found that the TN30 thermal throttles from turbo down to about the same level as the TN36UT's high mode after a bit anyway. Obviously the TN30 is cheaper - I got one in the expectation that running them with the Thrunite cells (or other higher-capacity but lower-current cells) might be viable to complement the higher-power flooders. I'm sure there are higher capacity cells that can handle the TN36UT current, as others are reporting.

Fluppeteer said:

I've no idea how people have been reviewing the TN36UT with these Thrunite cells - I swear I've seen at least one review that managed it.

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When my Thrunite 3400's were new, they would power my TN-36 UT without issue. I've seen reviews from both sides on Amazon. I think it's just borderline too much for these cells, and they work when at peak condition.

I'm going to order some new ones but not sure which exactly - probably LG MJ1, 3500 mAH 10A.

While I'm at it, anyone have some good info on 18350 cells for my EC11? People say Efest and AW are good, but they are rebrands. I would rather purchase Samsung/LG/Panasonic if I can find them.

I have the 8a keeppowers in my 18350 lights, spot on!

Perhaps, not the best advice, but I use unprotected batteries in my ThruNite TN32. Not a single issue so far.

Most of my 18650s are unprotected - the Thrunite protected cells are a really tight fit in the TN36UT, but all my others are fine. As far as I know, all is well - all the flashlights I own have a battery-protecting cut-out, although the TN36UT does seem to get quite close to the 3V line below which I gather one should not go. The MM15MB seemed to cut out at a higher voltage. That I saw some of my ThruNite cells at just below 3V might be because they weren't balanced after "charging" them on my cheap charger. I did see different behaviour from different Thrunite cells (some worked in turbo very briefly, some not at all, with the MM15MB). Other than unwittingly using them in a less-than-fully-charged condition, my cells were new, so I guess there's just some tolerance there and these flashlights run up close to it.

I'm using an Efest IMR 18350 (700mAh) in my TN Neutron 2C V2. (I'm mostly ignoring the capability to run off two and use the extension tube, because it'll hit not far off full turbo brightness with just one cell. The Nitecore looks nice, and I'd use the red LED, but it's quite a bit pricier on first glance; it looks like Selfbuilt hasn't got to it yet.) Again, I've not noticed any issues.

Annoyingly, the only thing that's given me problems (other than not being able to hit turbo on the flooders with Thrunite cells) is my Thrunite Ti3. My first one seems to have gone missing after I used it to try to help me deal with a bag inside which a drink had exploded. I ordered another (they're cheap and good gifts if I find the other one), but this seems much more prone to turning on when in - or clipped to the outside of - my pocket, and the mode control is less reliable than the original one, so it's sometimes managing to do so in turbo. I wouldn't have thought that was possible from a twisty light, but I'm probably going to burn through a few AAAs while I get used to it. Fortunately I somehow ended up with a house full of AAA lithiums...