Years of reading and battery safety is a mystery to me

airwolf41

Newly Enlightened
Joined
Sep 13, 2016
Messages
23
I have enjoyed many flashlights for the past 20 years, but due to a severe lack of technical knowledge, I have avoided any and all rechargeable flashlights.

Everytime I try to expand my knowledge, the info in the guides quickly go over my head. I read about how one needs to charge at a certain rate, how one needs to discharge at a certain rate, and store batterys in a certain charge status. I don't understand any of that or how to do it.

I would simply like buy a light such as a fenix or a Nitecore and would know nothing else except charge it and use it.

I guess these lights use Protected cells which I have read about and that seems reassuring, from what I can tell.

My main question is that I guess most rechargeables use what is commonly an 18650 battery? If I get a well known branded flashlight that has one of those batteries, am I getting anything more dangerous than a laptop or a cell phone?

Or should someone with my lack of knowledge just flat out avoid rechargeable lights.

I am interested in a Nitecore p20ix.

This nitecore uses a 21700 battery.

Even if anyone considers it ok for me to get an 18650 powered light, what the heck is a 21700, as it seems unique to Nitecore and would that mean is has less of a track record of being safe??

https://flashlight.nitecore.com/product/p20ix
 

chillinn

Flashlight Enthusiast
Joined
Jul 19, 2014
Messages
1,839
Here's your quick primer.

Only ICR, known as LiCo, actually LiCoO2 or lithium cobolt oxide, require a protection circuit, since this is the only chemistry that if discharged below 2.5V can form shorts in the cell (I believe called "dendrites,") and when placed back on a charger can cause a fire, or in extremely rare cases, explode and then cause a fire. So if you overdischarge LiCo cells below 2.5V, do not charge them, do not use them again. Find a battery drop and recycle them.

Every other available Li-ion cell chemistry tolerates overdischarge below 2.5V. Though it will still damage the cell, nothing bad will happen if placed back on a charger. They just won't hold peak capacity or put out peak current anymore. That's what happens to abused cells.

So the rule is do not overdischarge Li-ion cells below 2.5V, and never overcharge above 4.2V (or in some cases, for LiHV, or High Voltage Lithium Polymer, never over 4.35V).

If using lights with multiple cells, never remove the cells until ready to swap sets, because if you mix them up and place them back in the light, it could be bad.

Don't try to use a light that is cold and frozen when it has 3V Lithium primaries in it. Warm the light up first, or far better, toss the frozen cells and replace with room temperature cells.

Don't dispose of in a fire. Recycle Li-ion cells at a battery drop at your nearest hardware or big box store.

That is really all there is to Li-ion cell safety.

Best practices include never dropping your cells, and always rest your cells after use and before charging, and after charging and before use, at least an hour, two to be sure.

For multicell lights, create sets of cells that you never break up, and swap the location of the cells for each use for even wear. When initially choosing cells for sets, use new cells and match the resting voltages.

There really isn't anything else.

My main question is that I guess most rechargeables use what is commonly an 18650 battery?

Well, it's very popular, because 18650 has had a lot of R&D and advancements in capacity. This R&D interest has lately switched to 21700 cells, and we expect advancements in capacity here, mostly because Tesla has switched to using these cells in their electric vehicles.

If I get a well known branded flashlight that has one of those batteries, am I getting anything more dangerous than a laptop or a cell phone?

Not really, except the laptop or smart phone has a computer helping to condition the cells, watching its capacity and voltage, and should automatically not work with them anymore once the cell shows the computer signs it is or they are no longer any good.

what the heck is a 21700

It's a Li-ion cell. The convention for the numbered cells is the first two numbers are the diameter in mm, next two numbers the height in mm, so that cell is 21mm in diameter and 70mm tall. An ordinary AA 1.5V battery is also technically a 14500 cell, because it is 14mm in diameter and 50mm tall, though most commonly a 14500 cell is a 3.6V, 3.7V or 3.2V cell. An 18650 cell is 18mm in diameter and 65mm tall. An 18350 cell is 18mm in diameter and 35mm tall. It is very common for numbered cells to be slightly larger than their designation, so we often find large capacity 18650 cells that are 18.15mm in diameter, but I think you get the idea.

Samsung INR2170050E 9.8A 5000mAh is an example of a 21700 cell. Vapcell K40 INR21700 30A 4000mAh is another example. Molicel P42A INR21700 45A 4200mAh is still yet another good example. "mAh" is the capacity in milliamp-hours. The xxA number is the max current rating for continuous discharge in amps. Generally speaking, the highest capacity cells have a lower max current rating, and cells that put out a lot of current will have a lower capacity rating. You look at the specs for your flashlight, how much current it draws, and choose your cells based on that. I like my cells to be rated to handle at least twice the amps that my flashlight needs, but I have broken my own rule many times. I don't know NiteCore cells, have no experience with them, but many swear by them, though I believe it is possible to get better rated cells for less cost. If the light comes with a cell, use it.

Get different labelled cells from reputable manufacturers for a cell swaps. In no particular order, reputable Li-ion cell manufacturers include Samsung, Sanyo/Sony, Sony/Murata, Keeppower, Vapcell, Molicel, Imren, Efest, Surefire, and there are others I'll add as I remember. Only purchase from reputable sellers such as Illumn and Liion Wholesale (though I have purchased Keeppower cells from AliExpress, and they were legitimate).

In general, avoid using any cell made by a company with fire in the name other than Surefire, such as Ultrafire. I have seen that Olight makes some pretty crappy cells, no matter how loved their flashlight models are, their cells don't put out any amps.

There are lots of flashlight models that use 21700 cells. Noctigon, for instance, has several model flashlights that use 21700 cells. Zebralight sold a few models that use 21700 cells, such as their SC700 series. Many 21700 flashlights will also be able to use 18650 cells and 20650 cells as long as the cell's cathode (positive side) and anode (negative side) can reach the appropriate contacts in the light.
 
Last edited:

airwolf41

Newly Enlightened
Joined
Sep 13, 2016
Messages
23
Thanks for the response.

However, your response, highlights the reason for my post.

If I bought a flashlight right now, I have not the slightest clue how to know if I'm over-discharging a battery or overcharging a battery.

I have no clue of what "resting" a battery is, when to do it, why to do it, etc.

So it sounds like I should stay away from rechargeable lights.

When you mentioned a 3 volt lithium primary, are you referring to a CR123?

I have many lights that run on those and never knew anything about not using them when cold?

I thought cr123's were great for cold temp use in winter. I keep lights with CR123's in my car in Ohio winters.

Quite frankly I keep CR123 lights in my car year around. Am I doing something wrong here?
 
Last edited:

chillinn

Flashlight Enthusiast
Joined
Jul 19, 2014
Messages
1,839
Thanks for the response.

However, your response, highlights the reason for my post.

If I bought a flashlight right now, I have not the slightest clue how to know if I'm over-discharging a battery or overcharging a battery.

You get a decent smart Li-ion charger, such as one from NiteCore, it will take care of that for you.

I have no clue of what "resting" a battery is, when to do it, why to do it, etc.

Resting a cell simply means not using it. Resting a cell for two hours after you pull it out of your light means letting it sit there doing nothing before you put it on the charger. The idea is to allow all the heat to dissipate. In cold ambient temperatures, a hot cell can often rest in 10 minutes. But for conventional indoor ambient temperatures, CPF members recommend at least an hour of resting, i.e. sitting there doing nothing and not being discharged or charged, prior to placing on a charger. You do the same thing after it is charged, you set it aside and don't use it to let it rest. Two hours to 24 hours of rest is common. It's nice to have lots of cells so most of your cells are very well rested, for days and weeks, though, again, two hours is sufficient.

So it sounds like I should stay away from rechargeable lights.

With your level of confidence and comprehension after spelling out very carefully the extremely limited safety instructions, I'd have to agree. But for most, a light using a single large secondary Li-ion cell has been relatively safe. I really hope you can get your head around how to safely use Li-ion cells and your confidence grows, because there are a number of decent Li-ion LED flashlights now available, not to mention the joy of running high amp vintage incan flashlights.

When you mentioned a 3 volt lithium primary, are you referring to a CR123?

Yes, a primary cell is any non-rechargeable one use cell, and the most common 3V primary cell for flashlighting is a CR123A Lithium cell. Smaller CR2 lithium cells were also somewhat popular, and there are a few flashlighting holdouts that still use these smaller primary cells. A secondary cell is a rechargeable cell, whether Li-ion, NiMH, NiCad, etc.

I have many lights that run on those and never knew anything about not using them when cold?

In theory, it should not matter. Lithium primary cells should stand up to cold. But we had a CPF member significantly injured using a frozen cold light with frozen cold 3V lithium primary cells in it, and he had it in his mouth when it exploded. Which goes without saying, never put a light using lithium cells in your mouth.

I thought cr123's were great for cold temp use in winter. I keep lights with CR123's in my car in Ohio winters.

As above. When in use, the cells won't get cold. But heating something that is frozen quickly can and will cause thermal shock.

Quite frankly I keep CR123 lights in my car year around. Am I doing something wrong here?

No, maybe. Understand what thermal shock is. Also, don't pour boiling water into a frozen vessel. Get it? When the inside of a metal tube is heated up quickly, everything in it will expand, the air, the cells, the chemistry in the cells. The internal pressure will increase and if there is a weak point, it will find it, and it is usually going to be through the lens and out the front. But even metal will explode from thermal shock. Use quality CR123A cells, Surefire, Panasonic, Energizer, Duracell, Titanium Innovations, but be mindful of thermal shock if the light and cells are frozen. Further, multicell lights, primary or secondary, can be dangerous. If the charge reverses on one of the cells, for whatever the reason this can occur, it can cause an explosion. If the cell voltages are extremely mismatched, if the light has been sitting for a long time and one of the cells has lost a lot of charge due to self-discharge, the polarity of the cell can sometimes reverse, and rather than the light just being dim, one cell can explode, instantly causing the other cell to explode. This is more commonly known as a pipe bomb.

Lithium cells, whether primary or secondary, are not intrinsically safe, like NiMH cells are. In rare cases, things go wrong and bad things happen. Understanding li-ion safety and best practices is believed to reduce the frequency of such things occurring. But it can happen to even the most vigilantly safety conscious, or never happen to the most reckless. You should recall some national news after vaping became popular with people being injured by their vapes exploding. It is suspected in those cases there were bad quality cells pushed beyond the limits of their amp ratings. But if any cell gets too hot, it can cause thermal runaway, the cell is on fire, a very hot fire, sealed inside a metal tube, sometimes causing unexpected and rapid disassembly.
 
Last edited:

airwolf41

Newly Enlightened
Joined
Sep 13, 2016
Messages
23
You get a decent smart Li-ion charger, such as one from NiteCore, it will take care of that for you.



Resting a cell simply means not using it. Resting a cell for two hours after you pull it out of your light means letting it sit there doing nothing before you put it on the charger. The idea is to allow all the heat to dissipate. In cold ambient temperatures, a hot cell can often rest in 10 minutes. But for conventional indoor ambient temperatures, CPF members recommend at least an hour of resting, i.e. sitting there doing nothing and not being discharged or charged, prior to placing on a charger. You do the same thing after it is charged, you set it aside and don't use it to let it rest. Two hours to 24 hours of rest is common. It's nice to have lots of cells so most of your cells are very well rested, for days and weeks, though, again, two hours is sufficient.



With your level of confidence and comprehension after spelling out very carefully the extremely limited safety instructions, I'd have to agree.



Yes, a primary cell is any non-rechargeable one use cell, and the most common 3V primary cell for flashlighting is a CR123A Lithium cell. Smaller CR2 lithium cells were also somewhat popular, and there are a few flashlighting holdouts that still use these smaller primary cells. A secondary cell is a rechargeable cell, whether Li-ion, NiMH, NiCad, etc.



In theory, it should not matter. Lithium primary cells should stand up to cold. But we had a CPF member significantly injured using a frozen cold light with frozen cold 3V lithium primary cells in it, and he had it in his mouth when it exploded. Which goes without saying, never put a light using lithium cells in your mouth.



As above. When in use, the cells won't get cold. But heating something that is frozen quickly can and will cause thermal shock.



No, maybe. Understand what thermal shock is. Also, don't pour boiling water into a frozen vessel. Get it? When the inside of a metal tube is heated up quickly, everything in it will expand, the air, the cells, the chemistry in the cells. The internal pressure will increase and if there is a weak point, it will find it, and it is usually going to be through the lens and out the front. But even metal will explode from thermal shock. Use quality CR123A cells, Surefire, Panasonic, Energizer, Duracell, Titanium Innovations, but be mindful of thermal shock if the light and cells are frozen. Further, multicell lights, primary or secondary, can be dangerous. If the charge reverses on one of the cells, for whatever the reason this can occur, it can cause an explosion. If the cell voltages are extremely mismatched, if the light has been sitting for a long time and one of the cells has lost a lot of charge due to self-discharge, the polarity of the cell can sometimes reverse, and rather than the light just being dim, one cell can explode, instantly causing the other cell to explode. This is more commonly known as a pipe bomb.

Lithium cells, whether primary or secondary, are not intrinsically safe, like NiMH cells are. In rare cases, things go wrong and bad things happen. Understanding li-ion safety and best practices is believed to reduce the frequency of such things occurring. But it can happen to even the most vigilantly safety conscious, or never happen to the most reckless. You should recall some national news after vaping became popular with people being injured by their vapes exploding. It is suspected in those cases there were bad quality cells pushed beyond the limits of their amp ratings. But if any cell gets too hot, it can cause thermal runaway, the cell is on fire, a very hot fire, sealed inside a metal tube, causing unexpected and rapid disassembly.

I very much appreciate the time you have taken to respond to all these questions.

I am limited in my technical knowledge but am also a very skeptical, ocd, and very safety conscious person, so I am approaching from that persepctive.

Your lastest post has me far more confident in using rechargeables, as I now sort of disagree that my level of comprehension was lacking.

I respectfully feel your first response was quite vague, since I'm just now learning that the Nitecore charger will handle many of the overcharge/discharge issues.

Part of the reason of my post was trying to get the info as dumbed down as possible, and also focus on the fact that I am going to use a well known light brand and use it with the battery and charger provided. And part of me thought it would be odd for these lights would be sold to a person of my knowledge and not have protections in place.

But again thank you for your help.

You do have me really confused on the cr123 primary lights I have in my car. It sounds there is a is quite a risk to first powering these lights on in cold temperatures.

How would one know if the batteries are frozen to the tube and how could that even happen? Should I remove the batteries to look at them before powering on?



How much would the light need to warm up to be considered safer?

Just to note, in my limited knowledge, I did know that multi cell lights pose more issues, and I have ONLY been using single cell lights for years and only user name brand CR123's, almost exclusively Surefire cells.

But I FREQUENTLY use single cell CR123 lights in my car and we have seen negative temps here recently in OH, and I use the lights after they have been sitting in the car at these temps, sounds like a problem.

I also use flashlights with energizer lithium AAA's in them, including headlamps for camping that I also keep in my car, sounds like a headlamp with lithium AAA's would be extremely dangerous if it was powered on cold when on one's head from what your saying, I'm at a loss now learning all this.
 
Last edited:

chillinn

Flashlight Enthusiast
Joined
Jul 19, 2014
Messages
1,839
How would one know if the batteries are frozen to the tube and how could that even happen? Should I remove the batteries to look at them before powering on?
By "frozen," I just meant "very cold," as in freezing temperature of water and below. It's not that the cells are frozen to the tube, it's just if they are very cold. If your lights aren't drawing a lot of current, there is likely no risk. It takes a good amount current to cause cells to get hot. I'd say anything over 1 amp is a lot of current. With LED, that would be pretty bright, probably more than 160Lm. If you already know your lights, you should know if they get warm in your hands under ordinary temperature conditions. So if that light has sat in frozen temperatures long enough to reach thermal equilibrium, it will be the same temperature as the air. If you know the air temperature is freezing, avoid using a light that has sat awhile in the cold on mode brightnesses above 150Lm until the light and cells inside it slowly warm up. To avoid thermal shock, don't grab a freezing cold light and instantly use its highest brightness setting if that output is over 150Lm. Use a lower setting and let the light slowly warm up before using higher brightness modes. Slow is smooth; smooth is fast.

How much would the light need to warm up to be considered safer?

If it doesn't feel cold, and if it is the same temperature as your hand then it shouldn't, then it's probably fine. If it feels warm in your hand, you'll know its fine.

But I FREQUENTLY use single cell CR123 lights in my car and we have seen negative temps here recently in OH, and I use the lights after they have been sitting in the car at these temps, sounds like a problem.

Single cell CR123A lights are definitely safer than two or three cell CR123A lights. But I have used single CR123A lights that get so hot they can no longer be held, and I mean those made of aluminum that are 500Lm. They get hot. Test your lights. Bring them inside one at a time, let them sit over night, put in a fresh cell, and turn it on maximum. If after a minute, the light is hot, then you could have a problem if the light is frozen and you do the same thing. If it doesn't get hot in indoor temperatures even after a few minutes, you have little to worry about using the light when it is frozen.
 
Last edited:
Joined
Apr 13, 2020
Messages
249
My main question is that I guess most rechargeables use what is commonly an 18650 battery? If I get a well known branded flashlight that has one of those batteries, am I getting anything more dangerous than a laptop or a cell phone?

Single cell Lithium flashlights are rather safe if they have a good built in charger system or you use a good charger. Other than to protect shorts, you really don't even need a protected cell. The flashlight will prevent over discharge (just don't leave the battery in there for years), and the charger will prevent over charge, assuming you stick to the right chemistry for it. Lithium Nickel Cobalt is the most common and most chargers work just fine with it. The may not get 100% of the capacity as some cells take 4.3V, and many chargers are only 4.2V, but you get enough.

Some flashlights have the charger built it. They are rather idiot proof, like my magnetic attach charger Armyteks.

For cold temps, AA Eneloops are a good option. Hard to have the perfect flashlight for all occasions. Your lithiums will work at cold temps, but you will have significantly reduced runtime. You are not going to damage it discharging it, but the life is reduced. Just don't charge at cold temps.

LiFeP04 (Lithium Iron Phosphate) batteries, which are lower voltage, i.e. "3.2V", vs. "3.7V" are considered intrinsically safe, but they have less capacity. In automotive, companies like CATL have really pushed LiFeP04 density, but we are not seeing that at our level, and I don't think in 18650. I suspect many flashlights may run with them, but cut off early. You also need a LiFeP04 compatible charger. I just bought some 100Ah, 12V for my trolling motor. Prices have really dropped!
 

chillinn

Flashlight Enthusiast
Joined
Jul 19, 2014
Messages
1,839
LiFeP04 (Lithium Iron Phosphate) batteries, which are lower voltage, i.e. "3.2V", vs. "3.7V" are considered intrinsically safe
I have learned it really sucks to disagree with you, because no matter what, you can not be wrong, because you know ever damn thing, all of it, everything there is to know, you know it, have lived though it, and are expert in deep knowledge of it, even such droll subjects as thermal shock.

But you puncture a LiFePO4 cell and it can catch fire, expecially if fully charged, and youtube is chock full of examples of LiFePO4 cells burning, one in particular comes to mind that is very dramatic of a LiFePO4 motorcycle battery that spontaneously caught fire without any puncture.

I must absolutely agree that 3.2V LiFePO4 chemistry is safer than 3.6V or 3.7V chems, at the expense of lower capacity, and I very strongly suspect that is why it is safer, less energy.

But let's just agree to disagree on what "intrinsically safe" means and leave it at that, because as you know I am a damn moron with no education and three brain cells, and two of them don't work.
 

SYZYGY

Newly Enlightened
Joined
Sep 6, 2019
Messages
148
interesting discussion.

hopefully not too off topic, but i have a safety question.

this cell was used: https://www.vapcelltech.com/h-pd-41.html (Vapcell 18350 M11 1100mah 9A)

it was used in a D4V2 with boost driver. it was probably used in normal operation until it got low, and then it sat idle (with aux lights on) for quite some time. a month or more, maybe.

the cell was at or a bit below 2.3V. surprised it got so low. thought LVP would prevent that.

the cell was purchased last year. i did a capacity test on it, and it tested good (skyrc MC3000 charger) — almost as good as what it tested at when i first got it.

after reading this thread, since it's not ICR chem (it's INR), it sounds like it's safe to use. right?
also, NCR would also be safe in this situation, yes? ty
 

chillinn

Flashlight Enthusiast
Joined
Jul 19, 2014
Messages
1,839
since it's not ICR chem (it's INR), it sounds like it's safe to use. right?
also, NCR would also be safe in this situation, yes? ty

Yes, INR is LiNiMnCoO2, Lithium Nickel Manganese Cobolt Oxide, and can tolerate overdischarge, though it is hard to believe it sat there under 2.5V for so long and still has good capacity. INR cells usually do not have a protection circuit. The INR cell you linked to does not have a protection circuit.

NCR is LiNiMnCo, Lithium Nickel Manganese Cobalt Oxide, and it also is somewhat tolerant of overdischarge, but you should expect a loss of capacity.

Only ICR, LiCo battery chemistry, LiCoO2, Lithium Cobalt Oxide, should be discarded if it ever drops below 2.5V because it can form dendrites in the electrolyte, which can short the cell during charging, possibly causing fire, or in extreme rare cases, explosion and fire. Usually ICR cells have a protection circuit that will prevent the voltage from dropping below 2.5V. But not all ICR cells are protected.
 

airwolf41

Newly Enlightened
Joined
Sep 13, 2016
Messages
23
Single cell Lithium flashlights are rather safe if they have a good built in charger system or you use a good charger. Other than to protect shorts, you really don't even need a protected cell. The flashlight will prevent over discharge (just don't leave the battery in there for years), and the charger will prevent over charge, assuming you stick to the right chemistry for it. Lithium Nickel Cobalt is the most common and most chargers work just fine with it. The may not get 100% of the capacity as some cells take 4.3V, and many chargers are only 4.2V, but you get enough.

Some flashlights have the charger built it. They are rather idiot proof, like my magnetic attach charger Armyteks.

For cold temps, AA Eneloops are a good option. Hard to have the perfect flashlight for all occasions. Your lithiums will work at cold temps, but you will have significantly reduced runtime. You are not going to damage it discharging it, but the life is reduced. Just don't charge at cold temps.

LiFeP04 (Lithium Iron Phosphate) batteries, which are lower voltage, i.e. "3.2V", vs. "3.7V" are considered intrinsically safe, but they have less capacity. In automotive, companies like CATL have really pushed LiFeP04 density, but we are not seeing that at our level, and I don't think in 18650. I suspect many flashlights may run with them, but cut off early. You also need a LiFeP04 compatible charger. I just bought some 100Ah, 12V for my trolling motor. Prices have really dropped!

This is the light im interested in.

https://flashlight.nitecore.com/product/p20ix

Would this light be pretty much plug and play without giving much though to it and relatively safe?

Anything I should know about, as this light is pushing a lot of lumens.
 

KITROBASKIN

Flashlight Enthusiast
CPF Supporter
Joined
Mar 28, 2013
Messages
4,417
Location
New Mexico, USA
That Nitecore you linked is rechargeable; connect a USB C cord to charge. Have fun with it and let us know what you think of the double switch on the tail. Member chillinn is an ok person but this is being way overthought and some details are a bit suspect.

Nitecore is not going to give you a dangerous tool (though if you remove the battery, take heed not to short the circuit on that end of the battery with coins or something conductive). Resting batteries is the opposite of doing really foolish things that a kid might do; just not needed in of itself. That Nitecore has temperature sensing so it is highly unlikely to overheat whatever is done.

Sounds like you have good sense. Get it and try out all the features.

LFP battery technology is intrinsically safe. Can you start a fire with old hand sanitizer and a match? Yes but there is no need to be anti-queeky about it.
 

airwolf41

Newly Enlightened
Joined
Sep 13, 2016
Messages
23
Single cell CR123A lights are definitely safer than two or three cell CR123A lights. But I have used single CR123A lights that get so hot they can no longer be held, and I mean those made of aluminum that are 500Lm. They get hot. Test your lights. Bring them inside one at a time, let them sit over night, put in a fresh cell, and turn it on maximum. If after a minute, the light is hot, then you could have a problem if the light is frozen and you do the same thing. If it doesn't get hot in indoor temperatures even after a few minutes, you have little to worry about using the light when it is frozen.

Thanks again for responding to each concern I have.

As far as my headlamps, I use Energizer lithium AAA batteries and I'm guess that is just as dangerous as using a lithium CR123 as I'm guessing everything that applies to the CR123's applies to the Energizer AAA's?

My headlamp runs on three AAA's so I guess that makes it a multicell also which is bad for lithium, however, the headlamp housing is plastic so I don't know if that affects anything?

What you pointed out with lithium batteries concerns me most for my headlamps since those would obviously be near my face.
 

airwolf41

Newly Enlightened
Joined
Sep 13, 2016
Messages
23
That Nitecore you linked is rechargeable; connect a USB C cord to charge. Have fun with it and let us know what you think of the double switch on the tail. Member chillinn is an ok person but this is being way overthought and some details are a bit suspect.

Nitecore is not going to give you a dangerous tool (though if you remove the battery, take heed not to short the circuit on that end of the battery with coins or something conductive). Resting batteries is the opposite of doing really foolish things that a kid might do; just not needed in of itself. That Nitecore has temperature sensing so it is highly unlikely to overheat whatever is done.

Sounds like you have good sense. Get it and try out all the features.

LFP battery technology is intrinsically safe. Can you start a fire with old hand sanitizer and a match? Yes but there is no need to be anti-queeky about it.

Awesome, thank you for that response.

I know there has been a lot of talk back and forth here regarding extreme cold temps, I do use my lights in those situations and I know you and Chillinn are sort of butting heads a little but I appreciate both of your expertise.

In respect to Chillinn, I know he has concerns of lithium battery operated lights being stored in cold temps and then ran on high lumens, alleging they could explode.

Well this Nitecore with 4,000 lumens on that premise seems like it woud be a TICKING TIME BOMB.

I do a lot of cold weather camping and I take a lot of flashlights and Headlamps running on Lithium batteries, but this now sounds like an eventual recipe for disaster, epecially with a headlamp.

The last thing I need is a flashlight exploding on me in the back country when I am away from optimal medical help.

So this whole thread has me going back to the drawing board on anything I thought I knew regarding batteries, being good for cold weather.
 
Last edited:

chillinn

Flashlight Enthusiast
Joined
Jul 19, 2014
Messages
1,839
I'm guessing everything that applies to the CR123's applies to the Energizer AAA's?

I've been around, but I don't exactly know everything, but I have never heard of any event involving LiFeS2, lithium iron disulfide cells, which is the cell chemistry of Energizer Ultimate Lithium. Plus, under testing conditions, they can give a lot of current before the voltage sag is ridiculous, and there's not a whole lot of energy in AAA cells. Never say never, but unless you accidentally drop them in a fire next to your face... Energizers seem to be the exception among Lithium ion cells, but under extreme abuse conditions, like ripping the chemistry out of the metal container and taking a blow torch to it, it could burn a hole through you. Elemental lithium reacts violently with water, and explosively if there is enough of it. But in general, no one does that, so Energizers end up being really safe, especially if best practices are followed (like not using a dead cell with a full cell in a multicell light, though I am not sure Energizers would even do anything bad in that situation).

Well this Nitecore with 4,000 lumens on that premise seems like it woud be a TICKING TIME BOMB.

You'll have to look closely at a good review, but I suspect if it actually is 4000Lm, it couldn't be for very long.
X37Q3Q7_d.webp

Looks like a few seconds as it soon drops below 4000Lm, then drops rapidly to below 1000Lm at 30 seconds. This is pretty common, but by the description, sounds like a well built light with regulation. Maybe don't launch it into turbo when running with 2xCR123A immediately after pulling it out of a car it has sat frozen in for awhile, but otherwise, you should have no worries.

Member chillinn is an ok person but this is being way overthought and some details are a bit suspect.
I merely summarized boilerplate Li-ion safety and best practices in my first comment, what every member here tells new members. But I am pretty curious to know which details you thought were suspect, and you can not offend me, KITROBASKEN. We practice all day for accuracy. (FWIW Old Man LED & I have a history)
 
Last edited:

KITROBASKIN

Flashlight Enthusiast
CPF Supporter
Joined
Mar 28, 2013
Messages
4,417
Location
New Mexico, USA
Our nightly dog walk was in about 27°F, took about an hour and when we got home, I put the battery on the charger. CPF members here will have guessed correctly: no fireworks.

Others can refine the details if they wish regarding some of chillinn’s ideas, but I’ll just say the whole resting stuff is not a big deal unless things are being taken to extremes. That is my opinion.

CPF member old fashioned LED guy has the proper nomenclature for LFP batteries, not sure what post #16 second line is supposed to be.

The second post in this thread kind of looked like someone who either did not carefully read post #1 or wanted to provoke an obsessive compulsive episode. Or maybe the desire to masquerade as an expert trumped compassion or reason. We should help people asking questions, not trigger them, don’t you think?
 

Scotty321

Newly Enlightened
Joined
Jan 13, 2021
Messages
176
I have enjoyed many flashlights for the past 20 years, but due to a severe lack of technical knowledge, I have avoided any and all rechargeable flashlights.

Everytime I try to expand my knowledge, the info in the guides quickly go over my head. I read about how one needs to charge at a certain rate, how one needs to discharge at a certain rate, and store batterys in a certain charge status. I don't understand any of that or how to do it.

I would simply like buy a light such as a fenix or a Nitecore and would know nothing else except charge it and use it.

I guess these lights use Protected cells which I have read about and that seems reassuring, from what I can tell.

My main question is that I guess most rechargeables use what is commonly an 18650 battery? If I get a well known branded flashlight that has one of those batteries, am I getting anything more dangerous than a laptop or a cell phone?

Or should someone with my lack of knowledge just flat out avoid rechargeable lights.

I am interested in a Nitecore p20ix.

This nitecore uses a 21700 battery.

Even if anyone considers it ok for me to get an 18650 powered light, what the heck is a 21700, as it seems unique to Nitecore and would that mean is has less of a track record of being safe??

https://flashlight.nitecore.com/product/p20ix
I have the Nitecore P20i, P20iX, i4000R, and a couple of their older flashlights. The "i" series uses proprietary 21700's (generally Li rechargeable batteries can be understood by 21700 is about 21mm in diameter and 700mm long, 18650 is about 18mm in diameter and 650 mm in length). Other 21700 batteries will not work in them (I have tried Acebeam and Klarus without the +/- on both sides. I wouldn't let this dissuade you, as this seems to be the direction of the entire industry... Even similar length batteries with usb ports have different lengths (circuits and port adds to the length). Even my favorite Streamlight (Macrostream USB) uses a similar setup (although it ran on a generic 14500 I had... no charging through the flashlight USB port though). However, Streamlight's new 21700 battery has a wedge on one side so you can't use other batteries in it... I don't know if they will make an adapter for CR123's though.

IIRC, a couple years ago Tesla switched from 18650's to 21700's, and the industries followed... although there seems to be a new resurgence in LiPo this year (rectangle flashlights, powertools, etc.) The Nitecore P "i" series are about the same size and feel as the old Surefire (6P?) and feel great in the hand although a little large for pocket carry. They also sell a separate tailcap now if you want to tail stand.

Just my opinion, as I recently put the i4000R and P20iX in my box-o-flashlights (for use under particular circumstances), but I would only recommend the P20iX if you don't plan on using it over 20 yards. The 4000 Turbo is only meant to be used for a few seconds hear and there. It is impressive (4400 lumens in the discontinued i4000R), but the 4000 turbo works better to light up a large area at once, like a small parking lot or conference room for a minute or less. The other benefit to the P20iX is that you can program it for mode memory, although then the Turbo only comes on when holding the side switch, but you get an ultra low (2 lumens @ 5 candela). Tactical mode always comes on Turbo... and it gets hot.

** Side note, Nitecore offers cold weather 21700 and 18650's for purchase separately. If you're planning on going cold weather camping they might be handy.

Personally, I keep the P20i (not the "X" variant) as one of my bed stand lights and placed some DC Fix film from HD on the lense to give me good spill (light near my feet when pointing the flashlight straight ahead) and decent throw (light at a distance)... plus the "bloom" from the bezel crenulations was driving me 'batty'. With that setup, I can very clearly identify things across my yard (although it's only about an acre). The 4000 lumen P20iX will light up the entire yard for some seconds, but at 1700 or less (lower modes) it's really more for lighting up a relatively close area (great indoors or small outdoor area). For the record, my Streamlight HLX USB has almost the same range as the P20i but doesn't get nearly as hot with the 1000 lumen max... it doesn't have a charging port on the flashlight either though.

I think you'll have to decide on what type of beam profile you want... long range but relatively tight hotspot, close range but lights up the entire area, or a mixture (MH12S). I like my Nitecores if that helps any... I just prefer a different UI. Fenix might be a good competitive brand to compare with similar specs, UI, build quality, price, etc.
 

chillinn

Flashlight Enthusiast
Joined
Jul 19, 2014
Messages
1,839
Our nightly dog walk was in about 27°F, took about an hour and when we got home, I put the battery on the charger. CPF members here will have guessed correctly: no fireworks.

I'm not sure where you think I suggested there would be. OP was describing circumstances completely and utterly different, using his CR123A lights he left sit in a car in cold weather, as in frozen flashlight. Do you remember this?

Others can refine the details if they wish regarding some of chillinn’s ideas, but I’ll just say the whole resting stuff is not a big deal unless things are being taken to extremes. That is my opinion.

Resting cells has nothing whatsoever to do with Li-ion safety. That part was best practices, for those that take flashlighting seriously and want their cells to perform. If you don't care that your cells no longer hold capacity or put out amps, by all means abuse them by running them hot off your charger and putting back on immediately after use. I never suggested this was a safety issue.

CPF member old fashioned LED guy has the proper nomenclature for LFP batteries,

You put a nail through a NiMH cell, it isn't going to release poisonous fumes or catch fire. That is what intrinsically safe means. If punctured, LFP cells will release poisonous fumes and catch fire. So, in fact, "safe" is not an intrinsic property of LiFePO4 cells. They are safer than cells with more total energy and for precisely that reason. But they are not "intrinsically safe®," nor would any safety authority certify them as such, so, in fact, ofLEDg was in error and spreading false information.

not sure what post #16 second line is supposed to be.

I'm not sure what you're referring to, so I'll just quote the
entire first sentence, which takes up three lines on my display:

I've been around, but I don't exactly know everything, but I have never heard of any event involving LiFeS2, lithium iron disulfide cells, which is the cell chemistry of Energizer Ultimate Lithium.

What part were you having trouble with?

The second post in this thread kind of looked like someone who either did not carefully read post #1 or wanted to provoke an obsessive compulsive episode. Or maybe the desire to masquerade as an expert trumped compassion or reason. We should help people asking questions, not trigger them, don’t you think?

OP posted complaining with the title, "Years of reading and battery safety is a mystery to me." I answered all of OP's questions, and I concisely explained everything OP needed to know about Li-ion safety. I also added best practices to boot, because it's not a lot of information and easy to understand. OP had more questions, which I also answered, accurately, fwiw. And if you don't think safety is that big a deal, you should know that Li-ion cell failure has brought down planes. No big deal, right?

I'm really glad you posted, KITROBASKIN, because I and others are partial to you, and I know I am not only speaking for myself when I say we'd really prefer you not die in a fire.


Other 21700 batteries will not work in them (I have tried Acebeam and Klarus without the +/- on both sides. I wouldn't let this dissuade you, as this seems to be the direction of the entire industry...

Dear God, I hope not. I only first heard about such a thing recently, with a light by Thrunite that was sealed and wasn't supposed to be user serviceable anyway, and a light Streamlight used to to make. The only reason to design a light to only accept a proprietary cell is to fleece the customer and force them into paying more for a battery that should cost a quarter or a fifth of what they're charging. I wouldn't let this dissuade you, but I'll never invest in a light like that.

The good news is Scotty321 is mistaken, p20ix uses the Nitecore 21700 iSeries battery, which is just a ordinary 21700 battery with a built-in USB-C charger, and with the anode and cathode on opposite sides as indicated by the little plus and minus signs on the cell:
vvYnGqT_d.webp

1zsgWtZ_d.webp

So any decent 21700 cell that can provide the current the p20ix requires should do.

but I would only recommend the P20iX if you don't plan on using it over 20 yards. The 4000 Turbo is only meant to be used for a few seconds hear and there. It is impressive (4400 lumens in the discontinued i4000R), but the 4000 turbo works better to light up a large area at once, like a small parking lot or conference room for a minute or less.

As a CPF member since 2014 (not all that long considering), I can say I recognize this as some solid information. p21ix floods, does not throw, which surprises me because it does have a single emitter and a reflector, and yet I wouldn't doubt it.
 
Last edited:

airwolf41

Newly Enlightened
Joined
Sep 13, 2016
Messages
23
I have the Nitecore P20i, P20iX, i4000R, and a couple of their older flashlights. The "i" series uses proprietary 21700's (generally Li rechargeable batteries can be understood by 21700 is about 21mm in diameter and 700mm long, 18650 is about 18mm in diameter and 650 mm in length). Other 21700 batteries will not work in them (I have tried Acebeam and Klarus without the +/- on both sides. I wouldn't let this dissuade you, as this seems to be the direction of the entire industry... Even similar length batteries with usb ports have different lengths (circuits and port adds to the length). Even my favorite Streamlight (Macrostream USB) uses a similar setup (although it ran on a generic 14500 I had... no charging through the flashlight USB port though). However, Streamlight's new 21700 battery has a wedge on one side so you can't use other batteries in it... I don't know if they will make an adapter for CR123's though.

IIRC, a couple years ago Tesla switched from 18650's to 21700's, and the industries followed... although there seems to be a new resurgence in LiPo this year (rectangle flashlights, powertools, etc.) The Nitecore P "i" series are about the same size and feel as the old Surefire (6P?) and feel great in the hand although a little large for pocket carry. They also sell a separate tailcap now if you want to tail stand.

Just my opinion, as I recently put the i4000R and P20iX in my box-o-flashlights (for use under particular circumstances), but I would only recommend the P20iX if you don't plan on using it over 20 yards. The 4000 Turbo is only meant to be used for a few seconds hear and there. It is impressive (4400 lumens in the discontinued i4000R), but the 4000 turbo works better to light up a large area at once, like a small parking lot or conference room for a minute or less. The other benefit to the P20iX is that you can program it for mode memory, although then the Turbo only comes on when holding the side switch, but you get an ultra low (2 lumens @ 5 candela). Tactical mode always comes on Turbo... and it gets hot.

** Side note, Nitecore offers cold weather 21700 and 18650's for purchase separately. If you're planning on going cold weather camping they might be handy.

Personally, I keep the P20i (not the "X" variant) as one of my bed stand lights and placed some DC Fix film from HD on the lense to give me good spill (light near my feet when pointing the flashlight straight ahead) and decent throw (light at a distance)... plus the "bloom" from the bezel crenulations was driving me 'batty'. With that setup, I can very clearly identify things across my yard (although it's only about an acre). The 4000 lumen P20iX will light up the entire yard for some seconds, but at 1700 or less (lower modes) it's really more for lighting up a relatively close area (great indoors or small outdoor area). For the record, my Streamlight HLX USB has almost the same range as the P20i but doesn't get nearly as hot with the 1000 lumen max... it doesn't have a charging port on the flashlight either though.

I think you'll have to decide on what type of beam profile you want... long range but relatively tight hotspot, close range but lights up the entire area, or a mixture (MH12S). I like my Nitecores if that helps any... I just prefer a different UI. Fenix might be a good competitive brand to compare with similar specs, UI, build quality, price, etc.

I like lights that have a lot of spill. Most of my past lights uses have been for duty uses in addition to my outdoor excrusions. Most lights have enough throw for me, I like to overwhelm an area all around me with light.

I just want to trust that this light will be safe to use in more adverse conditions, which this thread has provided a lot of insight, as I have never ran a rechargeable light before.

I own several fenix lights, just no rechargeables so I'm also looking at the TK20R V2 vs the p20ix.

I did see that Nitecore offers cold weather batteries, and I guessing that is obviously a matter for performance and not safety.

The fact that a light could allegedly explode when having sat in cold tempertature and then abrupty powered on, had me take a pause. Particularly when it was mentioned that this potential event would be exaccerbated if the light was on a high lumen setting at the time it was powered on. 4,000 lumens certainly seems to meet that requirement.
 

Latest posts

Top