Nitecore i4

Hi, i just charge my Panas 3400 mah green 1 day ago.

This morning i decided to have some fun with my TK 75, and test out the runtime & heat management on turbo.

I put it to turbo, after like 20 mins i come to check out, and the light was quite a bit hot, a tiny bit before uncofortable to hold. So i decided to let it cool of a bit and re run.

Then on my suprise, the light would shut off on high only after 2 mins or so not quite sure how fast. I read on CPF taht this is charger issue, and not cells or flashlight.

I’m using Panas green 3400 mah…

Anyone got an idea what is the problem? charger? cells? flashlight issue? i got other charger, to test tonight but i got a bit nervous.

Do you have a multimeter?

What voltage are your cells coming off? Should be 4.2±.05V

I have three nitecore i4’s and they all charge perfectly to 4.20.

20 mins on turbo for a stock TK75 they should all still be on well over 4v.

Yes, even if 30 min on turbo, the light should not go to high after few mins! one user on CPF said that his TK 76 goes to high after 30 mins on turbo,

What he said…

AFAIK Fenix use great drivers on its flashlights, very good regulation, so this is very odd to me, there is some lose chain, batteries-charger-defective units??

I dont have multimer atm, tonight i will get it and other charger as well, but i must say i didn’t expected this…

Does the light turn off or just drop out of turbo? And are your batteries protected or unprotected?

1. Protected.

2. No it does not turn off, it goes to high mode.

Edit, i just tested, it goes to high after 30 seconds!

My Fenix TK70, 41 and LD12 will all go into high from turbo when the cell’s juice is not enough to sustain it. Time to recharge, as the cell’s voltage/s will quickly drop when used.

Yea, but my cells are fresh charged! last night i fully charged them….

~ 25 mins on turbo is nothing, afteral they are 3400 mah Pana cells, and are used on torch with high quality driver/regulation.

Well, go through the process of elimination. If you have your DMM, check the cell’s voltage. If all are ok, then there is small possibility that one of your cells have abnormally small discharge capacity left compared to the rest. (An analyzing charger/discharger is needed here). Also another possibility is, does your charger’s individual channel properly charges each cell? If all these test prove ok, then look at flashlight itself.

Yes, in few hours i will test everything as it should.

That has never happened to me. Did it happen also with the black panasonics?

Didn’t test with them, i will report back in few hours i’m 90% sure its batteries/charger.

Ok this is really strange. I recharged my cells in other charger, they came out around 4.16-4.17V

Then i tested runtime on turbo, 3 times for around 15 each making it like 45-50 min max overall.

What i notice is, that under 3.7V or 3.6V not sure, the light goes only ~ 2 mins on turbo and then goes to high! i read many reports of running turbo to around 90 mins withut stepdowns if you restart after timed step down which is around 20 mins.

What gives? bad cells/flashlight?

If you are pulling your batteries off and reading 4.16-4.17V it’s NOT a charger issue

So what can it be? is 3.6V to low for turbo?

How come others are getting ~ 90 mins on turbo without stepdowns? (3400 mah cells like me)

Are my cells damaged or what?

I have Orbtronic 3400mAh for my TK75vn KT[USE TO BE STOCK!]

I would get 62 minutes of turbo minus the split second step down every 20 minutes. the ONLY reason[s] it should step down to high:

  1. The 20 minute step down
  2. The batteries are weakening and can no longer sustain turbo

Any other reason there is something wrong w/ your batteries or the torch!

P.S. amazing as it sounds my run time is the same or very close to it even w/ the mod!!

My Batteries are 17 months old[mostly used on turbo] and I still get about 54 minutes of turbo! That was before and after the mod,which I got done a month ago!

You do NOT get 90 minutes of turbo!! Whoever told you that must have used an extension,then it would be 2h 54min. like I got!

When I got back from my walk after using turbo for 62 minutes minus step downs, the batteries were around 3.55V to 3.6V……….so yes, it can not maintain turbo anymore when the batteries are that depleted!

Don’t know anything about TK75, but if it has regulated driver on turbo assuming constant power you can get situation when those Panasonic cells are not the best choice. Sanyo or better yet some hi amperage cells would be better. In the process of draining you are getting lower and lower voltage. To maintaine constant power, driver pulls more current. When it pulls more current voltage drops even more. When driver detect some voltage limit it steps down. Simple as that. Hope you understand. I’ve experienced similar situation with some regulated drivers before, particular with THIS one.

Compare battery curves of Sanyo and NCR18650B with HKJ comparator. You’ll see Sanyo has higher curve at second half. In general higher curve cells are better for your situation. Also notice the protected cells have lower voltage curve. You should also compare curves at constant 10W power. You will notice down to 3.4V Sanyo 2600 can run 10 min. longer than protected NCR18650B regardless of capacity.

The 62 mins are without any 2 mins or so stepdowns right? you get full 3x 20 mins without going to high?

So i tested again and the runtime under fan on turbo is around 45 mins, after that it drops to high!

This is very low for 3400 mah batteries? :frowning:

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OP’S COMMENT

The 62 mins are without any 2 mins or so stepdowns right? you get full 3x 20 mins without going to high?
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As soon as it steps down to “High”, I bump immediately back to turbo. I do that for the duration of the battery charge for a TOTAL: Of 62/65 minutes of Turbo.It steps down no matter what,Like I said, I just bump up right away. If it keeps stepping down to high, that means the batteries are getting to low to sustain Turbo. It will do the same thing from High to medium when it can not sustain high. that is how the flashlight tells you the batteries are getting weaker.

You must have a faulty battery[batteries] or the charger is not charging them enough.As I said, my Orbtronic are 17 months old and I still get more turbo minutes than your new batteries!!