Protected 18650, meaning of "PCB is tripped" ?

Those two batteries you received with the headlamp are unprotected. It’s the same wrap used on protected and unprotected, Sofirn used the same wrap on the first version without protection until someone on BLF mentioned it. Their battery now has a black wrapper.

I’d just plain stay away from anything that cheap. Usually a safety risk

Any of you grabbed some led MCPCB and did the diode test with a multimeter? Diode test current is quite a low value (<2 mA), and you should see a value of ≈2.45 V on the multimeter's screen at that current. When you add a tiny driver plus other parts voltage drop overhead, you know cell voltage is quite unlikely to drop below 2.5 V even if left unattended for a while, and definitively will never drop below 2 V which is the absolute minimum value for li-ion cells safety wise. I tested what I say here attaching a couple of old cells to an led with some thin wires and magnets, and waiting until the die would very barely glow.

I won't repeat myself with this @#$%. And don't be anal with the too low voltage on a cell (as some of you take it), it's a bs thing in my opinion. I do not mean to say it may not matter, but ask yourself how much actual time will a cell remain at 2.5 - 3 V in a flashlight, probably very little if at all.

Sun, 03/15/2020 - 04:38

Anduril isn’t everyone’s cup of tea, way too many options and config being only 4 clicks, is annoying for some. It’s way too close to everything else. NarsilM was 16s hold and couldn’t be accessed by accident

I enjoy Anduril myself but would prefer config to be changed

The only thing that is a exception to this (light output is getting dim my battery voltage is low) is a light that excepts alkalines, Nimh and li-ion.
They contain a boost driver for Alkaline or Nimh. Once the battery falls below the vf of the led at a current load, the boost circuit kicks in and tries to maintain the current to the led. Most of these type drivers dont have any kind low voltage warning for li-ion. They can’t distinguish between if your using a Nimh or a very low voltage li-ion.

Barkuti is my battery management guru, but on this one point I disagree based upon a study. It has more data than I care to assimilate, but some of it is worth reading.
From another thread:
docware wrote: The study is dated 19.4.2017, cells are Panasonic NCR18650PD. You can read the whole study here :

It reads:
Rdc,10s (related to the charge transfer resistance of the NCA cathode) has increased by ca. 60% when discharging to 3.4 V, whereas it has increased by more than 200% when discharging to 2.5 V (from 4.1v. at 25C). Hence, microcracks of the NCA cathode and weakened particle contacts are assumed to aggravate with larger cycle depths and cause the marked impedance increase.

While I agree with anyone that says terminating a charge early or not draining a cell to low will prolong life of a cell.
My thoughts are that I usually only cycle any one particular battery of mine a few dozen times a year. I just have several batteries with several different lights.
So any one battery doesn’t get used that much per year. Then about every two years or so out comes a better battery in the same format. Like most people I buy a few to replace my out dated cells. I never really use any cells longer than about 4 years with a few hundred cycles on them, I have newer better cells to use.
So while draining them to 2.5v that’s suggested lowest in most data sheets could be considered abusing them. I will probably never see the day when it actual matters becuse I have already replaced them with something better.
Not everone will feel this way, and some people will want the cells to last as long as possible which is fine. Nothing wrong at all having health cell practices.
I have mixed feelings about what I read in datasheets and some test data. When you use cells outside what the test data showed or outside what’s in the datasheets things change a little, kind of uncharted territory in the cell data world. There were a few peolpe that experienced this uncharted territory in this thread.

That’s a interesting thread on battery voltage being to low.
Most of us received batteries that had been setting on a shelf for 3 years never used and measured 1.9v upon arrival. As comfychair said ” they appeared to be just taking a little nap”. I still have those cells at 11 years old now. Its about due for another discharge test.
If I was using them hiking and needed the light to see, it definetly wouldn’t bother me to squeeze ever last lumen out of the cell.

adjust your assumption:
the gas tank is empty at 2.7v
it is half empty at 3.6v

Lithium Ion Battery Safety 101

use your light until you notice it get dim, confirm the battery voltage on a meter at that point

now a warning
using a light with Two Batteries has a additional risk, IF they are not of matched charge. It is possible for the battery with higher charge, to transfer power into the less charged battery. This is dangerous. Therefore, I would not recommend a light with two batteries, to a newbie, unless they are of equal charge, age, condition. Dont mix and match batteries with different charge levels.

battery chemistry
Unprotected ICR is most dangerous
Unprotected IMR and INR is less dangerous


On another note, I’ve had two cells (18650, 26650) that appear to have protection circuits in them.
The cells were 70mm long with button tops and space for the protection.
Both had the higher resistance expected from protected cells.
One was an 18650 crap cell included with an “as seen on TV” zoomie that tested way below the rated “5000mAh” (naturally).
The second was a 26650 that was rated at 5000mAa and tested to 5400mAh – a nice surprise.
This was included with an $11 light from Amazon.

In both cases the lights and the cell protection allowed the cells to be discharged below 2.5v.
So it would seem that there are some “protected cells” that the protection may not do what we normally expect.

I wonder just what would trigger the protection? It’s not undervoltage.
Perhaps an over current situation is what these are designed for?

This maybe what you have going on with your setup.
All the Best,

Protection doesn’t always work so never rely on it. Learn about lithium safety and use with a flashlight that is confirmed to have a low voltage cut off.

Jeff51 - sometimes cheap protection chips cut off lower than 2.4v so you may have not taken it low enough yet.

I’ve had cheap cells with protection charge when reversed in a charger. Scary stuff. Gave an error inserting the correct way but started charging when reversed

I had 2 incidents with battery tripping.

My Sofirn 14500 tripped so I zapped it with 12v just briefly. It worked in flashlight, stored it away and then no work few weeks later in flashlight.

My Pansonic Eneloop Pro AA went to 0V. It wouldn’t charge again right away. Few hours later put back in charger and it started to charge. Now it’s fully charged and okay! :smiley:

Hope this helps. :slight_smile:

A protection pcb is a electronic circuit with electronic components. It is a electronic form of protection for the battery running outside of acceptable perimeters.
A TV is a electronic circuit with electronic components, you ever had one fail?
Its there just incase the user doesn’t follow proper use. They do fail and sometimes dont trip at the right times.
Its better to learn proper use, and use the protection circuit as a back up.
Its like driving and using the seatbelt to save you from your bad driving all the time. Learn to drive properly and you want need to rely on the seatbelt. :smiley:

I’ve had no trouble reviving protected cells with low voltage protection tripped.
Some chargers will do it just fine. I’ve also had cheap headlamps with built-in charging do it also.
This is with no-name protected cells that came with the headlamps.
These lights have no built in protection. They run till you think it gets too dim or until the LVP tripps.
I’ve done this several times with these lights.

Also you can just use a working cell to reset the protection.
All that’s needed is to put the “tripped” cell in parallel with the working cell.
It would be a good idea to use a resistor in between to prevent a big current surge.

Others have used a pair of AAA in series to provide 3v to put in parallel with the tripped cell.

I have seen POSTs where the protection circuit has died and no tricks work to bring it back.
In that case the cell might be just fine.
Remove the wrapper and disconnect the electronics, check the voltage, and presto – a working non-protected cell.
A little more info from HKJ
All the Best,

Thanks for the reference links. I had read those before but somehow I failed to notice that a LED will stop working properly when the cell is close or reaching the cutoff low voltage. Now that I know this detail. I will just go will unprotected Samsung INR18650-35E. I have no usage of high current, careful by nature and I use a Nitecore new i2 charger. I think that I could manage with unprotected cells. The overhead of the protection mechanism may even be counter-productive for my case.

Once I receive the new cells, I will proceed for the test procedure you advised to learn about the safe runtime of the cell. This headlamp uses 2x 18650 in parallel. When I remove one, it works perfectly with the same brightness. So I think I will carry the 2nd as backup cell to avoid the multi-cells scenario.

I have the exact same headlamp and it drains the cells below 2v.

This hasn’t been my experience. I’ve had many flashlights with no low voltage protection discharge under 2v

2.5v on load should be the absolute minimum but not all batteries, you need to check the datasheet for each model. The reviewer HJK has stated that he no longer runs tests down to 2.5v anymore due to ruining some batteries, he now only tests to 2.8v.

I do however just immediately switch off a light once it goes dim. If you leave it on once it’s dim it’ll very quickly drop too low.

Do not attempt to charge a battery that’s under 2v unless you know what you’re doing.

Did you get that? safety wise, not ruling out damaging your batteries irreversibly.

Since you are carrying the spare battery, why not carry it in a flashlight with Anduril UI? Then you can check the approximate voltage of the battery you are using by putting it in the flashlight. Just make sure to lock it out so it does not come on in your pack/pocket when hiking. Really, it is not difficult to click three times, I do it often and have no issues, trust me. And you have another flashlight available as a backup or to use around camp. I always carry a backup light… one is none and two is one, etc.

And yes, if both batteries get down to 3.4V anyone would run them down on an overnight trip. But that is something that has not happened to me. On a longer trip, carry more batteries. Then you can relax and enjoy the outdoors.

I just don’t know why someone would risk using those cheap batteries, they are a safety risk, period.

Years ago I saw a thread on BLF of a SkyRay flashlight literally explode which blew out his apartment windows. This was a result of using the cheap Chinese cells it came with.

I’ve seen multiple stories of Chinese cells catching fire, smoking, exploding. Just don’t use them, purchase something decent such as LG, Sony, Samsung, Panasonic etc

I’ve even seen some covered in rust when I removed the shrink wrap for my RC heli.

Same for lights that take (non-rechargeable and nominal 3v) CR123A as well as (rechargeable and nominal 3.6v) 16340. Some models do have LV warning and/or cutoff for rechargeables, but the LVP is defeated if the battery is reconnected when its voltage is lower than about 3.3v. The driver resets and assumes it has the lower voltage non-rechargeable, which of course can be safely driven into the ground.

Is there any kind of required standard compliance to prevent such an irresponsible design?!?

Or maybe any flashlight that has a LED displaying red when the battery is low could also do the job? I am not sure if my next flashlight would have Anduril UI.

Simple by ignorance. I ordered that headlamp on eBay end Jan 2020. At that time, I was vaguely aware that I should use genuine brand name 18650 cells. I just ordered those 2 cheap cells anyway, at least I could use the headlamp right away. In fact, I think most customers, myself included would feel happy as they have no way to know to judge the quality of the products.

Thanks goodness I got educated now thanks to BLF members. And the reason was pretty silly, I was looking for a way to disable the next memory mode in my other eBay flashlight. That was then I discovered a whole world of better designed flashlight and in particular about the Li-ion cells. Here’s another example of benefit I had learnt thanks to the BLFers. I bought some DC-Fix Diffusion Film , just to playaround. I put a diffusion film and an orange filter on a cheap ebay flashlight. And miracle, the ugly beam is transformed into a nice warm light without any hard hotspot.

So now my solution is simple. I’ll give up on those cheap 18650 cells and that F&^%! headlamp. Or maybe keep it around as backup. The winter is over now, the evening walk is not that dark. I have almost a year to order a multimeter, brand name cells & headlights.

use of unprotected LiIon requires an educated operator

as moderator007 pointed out, there will be no built in LVP in most lights that are dual fuel, that is, a light that can use either a primary or a LiIon, will not prevent overdischarge of the LiIon, because primaries get used to lower voltage levels than LiIon.

for those reasons it is recommended to use Protected LiIon in unprotected lights.

even so, an educated operator, can use unprotected LiIon, IF the operator takes responsibility to monitor Voltage.

now the granny scenario
I lend a light to granny, that has no LVP, and is loaded with unprotected LiIon.
she falls asleep with the light on, and it overdischarges the cell…
IF the cell is INR or IMR, odds are good there will be no Venting with Fire, upon recharge

but in the interest of safety, recharge in a fireproof location, and remain present to monitor the charging cycle, to ensure the battery does not overheat

Do NOT put LiIon on charge overnight, while you are sleeping…