Li-Ion protection technology and possible dangers

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NewBie

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greenLED said:
I guess this is slightly OT, but why don't li-ion cells have raised "button-tops"?

Because most of those types are bare cells, the most dangerous of all the cells you can obtain.

They are not unprotected.

Nor are they protected.

They are bare- Please go back and read the thread from the beginning.
 

NewBie

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greenLED said:
I guess this is slightly OT, but why don't li-ion cells have raised "button-tops"?

They do.

The very dangerous bare ones do not.

These are not supposed to be used without a bunch of fancy protection mechanisms added to them before you use them. They are intended for making battery packs out of.
 

TooManyGizmos

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I did read most of this thread and others like it , enough to say it's scary . I don't recall any mention of this so I will propose an analogy.


These battery issues remind me of the used oxygen canisters improperly packaged that reportedly somehow ignited violently in flight and brought down a commercial jet several years ago .

Are there any similarities in batteries & oxygen canisters and how they work. Is it possible in some way that discharging battery power caused those canisters to erupt ? Is there anyone reading this who understands oxygen canister science/engeneering and how they failed .

Could this analogy be used to warn people further about these new battery chemistries and designs - some not even meant for amateur consumption cause were too ignorant of the dangers .

Are we , in a way , playing with equivelent oxygen canisters inserted into a flashlight tube creating a potential pipe bomb ? A roman-candle flashlight ?


Lets all be real careful....If you don't know what you're doing.....DON'T do it . Don"t play with fire .




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TooManyGizmos

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What possible hazard is posed by those overdriven Golston 7 WATT Luxeon lights.

If one is left on a long time , suplying a heavy load quickly draining and heating up the Lithium batteries in it ,whats gonna happen if those Lithiums are'nt evenly matched .


I don't wanna be holdin it ............... or near it .

Overdriving Lux's combined with multiple Lithium batteries......:oops:.



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NewBie

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TooManyGizmos said:
What possible hazard is posed by those overdriven Golston 7 WATT Luxeon lights.

If one is left on a long time , suplying a heavy load quickly draining and heating up the Lithium batteries in it ,whats gonna happen if those Lithiums are'nt evenly matched .


I don't wanna be holdin it ............... or near it .

Overdriving Lux's combined with multiple Lithium batteries......:oops:.



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Just pushing the Li-Ion cells outside their ratings is a dangerous thing to do. The interesting thing is that once the cell is abused, the potential for a disasterous event increases. Many of the folks that are hurt by Li-Ion cells each year, were not caused by the user abusing the cells at that time. Often it comes at a later point, due to what the cell was exposed to earlier.

It is also dangerous to push a single cell outside it's specification, it is not an issue with just a multiple cell senario.

You don't have to be abusing the cell at the time, in order for the event to occur.

An example would be when a dendrite growth is created, or when Lithium is plated out of the chemistry due to the cell being pushed beyond it's rating. The Li-Ion has a maximum discharge rating (and on plenty of cells it is not 2C). Pushing it beyond this rating results in the normal Lithium Ion exchange not to occur properly, and things don't recombine as they would normally, keeping everything in the Ion transfer state. This results in a layer of raw Lithium, which is just waiting to start a chain reaction. Pushing them beyond their rating also causes dendrite growth, which can form a near short within the cell, just waiting for something to happen that closes the path for an actual short.

Once the cell goes into thermal run away, a PTC isn't gonna do much at all. The PTC is mainly there to prevent the cell from getting hot enough to get into a condition for the thermal runaway situation in the first place, and to prevent too much current from being pulled out of the cell, such that the cell can get warm enough for thermal runaway. That is why they usually put the PTC's on each individual cell. Often the thermal runaway condition, since it is internal to the cell, is a self sustaining situation that cascades. If one is feeling extremely lucky, it may be possible, if the thermal runaway starts to occur during use, that removal of the load, could possibly reduce the likelyhood for the condition to grow and get worse. But in reality, the PTC should have kicked off long before the cell went into thermal runaway in the first place.

It is interesting how professionals treat these cells, with multiple protection mechanisms, both electrical, thermal, chemical, and mechanical. It just occured to me that the technique seems alot like a nuclear power plant.
 

Lunal_Tic

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Is it possible to test/check existing cells to determine if they should be retired? I've run a number of hotwires that have gotten quite hot but because I've got a lot of batteries I don't know which were or might have been stressed.

-LT
 

IonFire

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Excellent work Newbie.

I am so glad someone did this, it wasa long time coming i believe.
http://www.batterymart.com/battery/ACC-CH-RCR123AC03.html

These are them powerizers, not recomended for use in flashlights, probably good reason too.

I did however get a bit confused here on your post, i have re-read it a couple times, have sourced outside info and i still don't get how a cell can be unprotected an protected at same time, i am assuming this would mean the cell has some protection like low/high volt cut offs, and no temperature, short or other protection installed, is this correct Newbie?

I have some Li-ions sold to me as protected, but i can not find crap on them from the manufacturer ect about thier real abilities, any suggestions bro?
Thier Hitech GN Li-Ions, sold as protected 3.6-4.25 volt batts.

I really apreciate all the hard work you have done, thanks for compiling it for us man, very nice of you to do.

peace IF
 

SilverFox

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Hello Lunal Tic,

A Li-Ion cell should be retired when it falls below 80% of its rated capacity at around a 1C discharge.

When all this nasty stuff that NewBie is talking about happens, the first result is a loss of capacity. Things go downhill from there.

Tom
 

Lunal_Tic

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Thanks Tom,

The only thing is I've no clue how to test that. My new handy dandy ZTS battery tester is about as complex as I've managed in the world of battery-aholism.

-LT
 

NewBie

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IonFire said:
Excellent work Newbie.

I am so glad someone did this, it wasa long time coming i believe.
http://www.batterymart.com/battery/ACC-CH-RCR123AC03.html

These are them powerizers, not recomended for use in flashlights, probably good reason too.

I did however get a bit confused here on your post, i have re-read it a couple times, have sourced outside info and i still don't get how a cell can be unprotected an protected at same time, i am assuming this would mean the cell has some protection like low/high volt cut offs, and no temperature, short or other protection installed, is this correct Newbie?

I have some Li-ions sold to me as protected, but i can not find crap on them from the manufacturer ect about thier real abilities, any suggestions bro?
Thier Hitech GN Li-Ions, sold as protected 3.6-4.25 volt batts.

I really apreciate all the hard work you have done, thanks for compiling it for us man, very nice of you to do.

peace IF


Okay there are bare cells, with no PTC. These are usually the ones with no button top, and are intended for a bunch of fancy additions that are used in battery packs.

Then there are unprotected cells, which have mechanical/chemical/thermal protection mechanisms, such as the CID, PTC, fuseable link (different than a PTC).

Next come the protected cells, which have all the mechanisms of the unprotected cells, but will add on electrical versions of high temp, over current, over voltage, under voltage, and various other protection things.

It is definitely not recommended to use just electrical protection with bare cells only. The reason why is that there have been many cases where the electronic protection has gotten static zapped (due to cheap design-it can be avoided), and once the thing has been zapped, you are running nothing more than a bare cell.

On a side note, in another thread that I saw...my thoughts on it:
Putting just a PTC in line with a series of bare cells is one of the most ignorant things I have ever heard of, for protection mechanisms. It borders on ignorance, lack of understanding, and one hell of alot of danger, especially with D sized Li-Ion cells. I highly doubt even the Chinese would consider doing this on a product.

I hope like heck nobody gets injured!
 

milkyspit

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Slightly off-topic in that these don't specifically address the DANGERS of the Li-Ion chemistry, though the information they contain does help one avoid the pitfalls... posted here in the interest of gathering as much related stuff as possible in one thread, as one poster farther back suggested...

The Power of Li-Ion. Good (and short... four pages) overview of the state of Li-Ion technology, who makes what, relative dangers of various types of Li-Ion technology, etc. Written in 2000 but still seems quite relevent.
linux-7110.sourceforge.net/howtos/netbook_new/LIbattery/liion.pdf

LG 18650 Li-Ion Cylindrical Cell Datasheet. Linked from BatterySpace.
www.batteryspace.com/productimages/li-ion/186502400A2%20PS.pdf

14500 Li-Ion Cylindrical Cell Datasheet. Linked from BatterySpace.
www.batteryspace.com/prod-specs/Li-Ion%2014500.pdf

Hope these help someone.
 

jsr

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NewBie said:
Okay there are bare cells, with no PTC. These are usually the ones with no button top, and are intended for a bunch of fancy additions that are used in battery packs.

Then there are unprotected cells, which have mechanical/chemical/thermal protection mechanisms, such as the CID, PTC, fuseable link (different than a PTC).

Next come the protected cells, which have all the mechanisms of the unprotected cells, but will add on electrical versions of high temp, over current, over voltage, under voltage, and various other protection things.

Newbie - I'm looking into some 17500 and 14500 cells from e-lectronics.com. E-lectronics' cells do not have a button top, but the e-lectronics owner claims they have a protection IC built in (even specifically calls the cell "with IC").
Is this possible that it is a fully protected cell with no button top? Or am I being BS'd?
The owner states he carries both unprotected (no IC) and protected (IC) cells, but neither have button tops. You seem to state that if it doens't have a button top, it cannot be protected. Need help on this as I was looking to purchase some of these very soon.

Thanks for your help and knowledge.
 

srvctec

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jsr said:
Newbie - I'm looking into some 17500 and 14500 cells from e-lectronics.com. E-lectronics' cells do not have a button top, but the e-lectronics owner claims they have a protection IC built in (even specifically calls the cell "with IC").
Is this possible that it is a fully protected cell with no button top? Or am I being BS'd?
The owner states he carries both unprotected (no IC) and protected (IC) cells, but neither have button tops. You seem to state that if it doens't have a button top, it cannot be protected. Need help on this as I was looking to purchase some of these very soon.

Thanks for your help and knowledge.

I'm not Newbie, but I ran into the same problem after reading this thread as well. I ordered a 14500 thinking it would have a button top, not realizing that the "button top" is basically flush with the end. Technically it has a button top, but not really- are you totally confused now- me too? Here are some pics of a protected Li-ion to clear things up.

Positive end
Li-ion1ars.jpg






Positive end
Li-ion3ars.jpg





Negative end
Li-ion2ars.jpg


You may need to get some really small magnets (I got mine at Lighthound (CPFer jcciv) since he sells them as well as the batteries) to go along with your protected Li-ions which will stick to the positive "button" so the battery will make contact with it's intended connection. Your application may not require this magnet depending on if the point at which the positive end of the battery makes contact has a raised blob of solder or a button of it's own.

I am by no means an expert on this, this is just what I have learned in the last week after having ordered my battery.

Hope this helps someone else in the same boat.

jsr- Maybe the guy at E-lectronics is calling a battery like the one above "no button top" because the button doesn't protrude above the battery casing- just a guess.

I don't mean to step on your toes at all Newbie- you are obviously very knowledgeable in this field, I was just under the impression all protected Li-ions had a button top that protruded above the battery casing.
 
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greenLED

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AFAIK, the thin metal strip on the positive contact is part of the protection PCB. Feel free to contact Markcm directly with your questions, he is very helpful. There's an entire thread devoted to his batteries, BTW - can't remember the name, though. :)

I am weary of using a magnet as contact. If it ever were to slip it could cause a short and... :poof: :green:
 

chimo

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Here is an example of what that little strap goes to. This is a small PCB that is under the tailcap.

This is from one of AW's cells. AW's batteries use a better method than some others I have seen to protect the PCB and ensure good wear resistance on the cathode contact.

The little strap on the left goes to the anode contact. The tab on the right (B-) goes to the actual cell cathode. The big blob on the bottom goes to the steel baseplate of the battery on the other side of the PCB. The circuit acts as a switch on the cathode of the battery. The switch will open if the current is too high or the voltage is too high or low.

 

jsr

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Thanks guys. I did contact MarkCM and that's how I found out he has both protected ("with IC") and unprotected ("without IC") LiIon cells, but he also stated both types are "flat positive terminals". I've contacted him again to get clarification on whether "flat" means "flush button-top".
 

cy

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srvctec said:
You may need to get some really small magnets (I got mine at Lighthound (CPFer jcciv) since he sells them as well as the batteries) to go along with your protected Li-ions which will stick to the positive "button" so the battery will make contact with it's intended connection. Your application may not require this magnet depending on if the point at which the positive end of the battery makes contact has a raised blob of solder or a button of it's own.

I am by no means an expert on this, this is just what I have learned in the last week after having ordered my battery.
using a small magnet is not a good idea. sudden jar could slide magnet, possibly causing a dead short to ground.

much better to aply a dab of solder to positive contact, to make connection with flat top cell.
 

NewBie

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jsr said:
Thanks guys. I did contact MarkCM and that's how I found out he has both protected ("with IC") and unprotected ("without IC") LiIon cells, but he also stated both types are "flat positive terminals". I've contacted him again to get clarification on whether "flat" means "flush button-top".


Keep in mind, there are at least three types out there:

-Bare: No safety features but a vent

-Unprotected: Often fused, vented, CID, and PTC

-Protected: All the above plus electronics. Not all protection electronics are created equal, and some are much better than others. Better ones include ESD protection, battery thermal sense, etc...
 
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