greatest danger using li-ion cells occurs during re-charging

cy

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I've noticed as li-ion cells age, their ability to receive a full charge goes down. so a charger that keys on voltage alone will keep attempting to charge until set volt is reached.

when you remove cell from charger after termination to end voltage. cell will quickly drop.

just repeated this with a protected R123 cell charged to 4.1v and repeated to 4.2v. both instances cell dropped to 4.02 after removal.

SilverFox said:
When the cells are healthy, this should not present any problems, however as the cells age they will be subjected to a trickle charge for an extended period of time. ~

Back to the aged cell. The cell is considered "dead" when its capacity drops below 80% of its initial capacity. The reason the capacity drops is because the internal resistance of the cell goes up. This increase in internal resistance limits the maximum voltage of the cell. This means that it spends more time holding the constant 4.2 volt as the current tapers off. If your current never shuts off, you can effectively trickle charge it for quite a while as the cell struggles to stay at 4.2 volts.

As soon as you remove the cell from the charger, the voltage will drop on a cell with increased internal resistance. Your cell may have been charged to 4.2 volts, but when you take it off of the charger it may drop down to 4.12 volts, or something like that.

Tom
 

MrAl

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Hi Tom,

That's a good question, and my best guess is that they simply seek to define what
is a fully charged cell and what is not. Not all specifications are there to protect
the product and by specifying some low charge current cutoff point they also
provide some reasonable length of time that they can call the "required charge time".
If it were not for that cutoff point (which is easier to measure by current level)
the charge time could be many hours, with the many hours after the cutoff point
contributing little to the total charge.
For example, it may take two hours to reach the low current cutoff point, but
another four hours to reach say 1ma. Would you rather say your product charged
in two hours or in six hours? This doesnt mean the cell is going to warp into another
dimension if it's charged for six hours, but it does give the manufacturer a nice
selling point which is competitive with other cells like it.
Another way of saying this is that if the little green LED lights up after 2 hours
most people will be more happy with their charger than if it takes 6 hours and
the last 4 hours of that time didnt do much.

There are other good examples of where the spec's are a bit misleading, and another
very good one is about charging this very kind of cell...
The spec says something like: "Charge with a constant current and then with
a constant voltage". The misleading part is the 'constant current' part because
a constant current is a current that is fixed at one specific level, and that level
does not change. In actual practice there is no reason why this current can not
change however, as long as it does not exceed a certain upper level. In this
case the upper level point is more critical but the better way to define this is to say
it is a "current limit" and not a "constant current". The main point is that
either way the cell gets charged and there is no damage to the cell, but the
selling point here is that with a constant current the cell does in fact charge
somewhat faster than with a current limit in some designs, although the difference
can be very small.
Designing a constant current can be much more costly than a current limit,
but then again even a current limit is a bit misleading, because it should
really read "approximate current limit", where the upper set point is
roughly near the max for that cell (within maybe 20 percent or so).
Some people could even think that 'constant current' means
"precision constant current" or that "current limit" could mean
"precision current limit", where neither of these are correct.
Maybe it should read, "Charge with any dang current, just dont go
too high above the max spec, and then switch to voltage mode".
The only drawback would be if 'any dang current' was too low it
would take much longer to finish the charge.

These are both examples of where the specification seems to take on more
meaning than it was originally intended to have. This is something like where
a parts tolerance is over specified, making a project much more costly than it
should really be.

Of course some specs must be taken as exact and should not be changed,
such as the max voltage spec of 4.2 volts, which is allowed to go as
high as 4.25 volts but not any higher no matter what or damage can
be done to the cell.

We thus have to recognize these two different kinds of specifications
so we can design cost effective products that are also safe to run.
 
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PhantomPhoton

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Is this the Pila IBC charger that you are talking about?

Pila IBC Charger

jsburlys seems to be the only place selling it on my list of flashlight bookmarks. Feel free to add in more places that offer it but this one was the only one I could find without significant hassle.
 

Led-Ed

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That's the one, Phantom.Great charger that I use for all my Li-ion cells.
 
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LuxLuthor

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The Pila 2 slot charger is well designed, but limited by its 600 mA per slot charging rate which takes a long time. I think the next best charger is the DN/Tenergy setup with AC power adapter, but you still need to get the Voltcraft cradle sent from Europe and modify it. Beyond that you are into the Triton, Schultze, Hyperion, or other brand of Hobby chargers & balancers...but still need the cradle.
 

cy

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yes this is the correct model, but please note this is not valid for early Pila chargers. which were completely different.

early pila chargers were dumb chargers and contained no termination electronics. they depended completely on pila cell to terminate charge. charger puts out aprox. 4.8v.

it's amazing how many different versions of loose li-ion cells and li-ion chargers that's been available through cpf sellers for the last two years.

li-ion cells.JPG


PhantomPhoton said:
Is this the Pila IBC charger that you are talking about?

Pila IBC Charger

jsburlys seems to be the only place selling it on my list of flashlight bookmarks. Feel free to add in more places that offer it but this one was the only one I could find without significant hassle.
 

Phredd

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cy said:
1. recognize greatest danger of using li-ion cells occurs during re-charging.
2. invest in a hobby grade charger and avoid use of low end chargers.
3. use li-ion cells with overcharge protection if you are not going to invest in a hobby grade charger.
4. don't charge in series without balancer leads going to each cell.
5. safest way to charge li-ion cells is in singles.
6. it's safe to charge li-ion cells in parallel as cells will self balance.
8. never charge li-ion cells unattended
9. charge li-ion cells in a protected area, so if fire should occur. your home will not burn down.
10. discharge larger li-ion cells to 3.4v before shipping. this removes almost all stored energy in cell.

Is #7, "don't over-discharge"?

I'm new to unprotected lithiums. My first Orb is in the mail. I thought the most danger was in over-discharging, because then the cell could explode during charging.

Phredd
 

cy

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many thanks for pointing out #7 is missing. shows how difficult editing you own writings is.

#7. be aware of dead short dangers. li-ion cells can discharge at high rates.

this includes dead short dangers while handling cells. check to make sure there will be no internal dead shorts. positive nipples on li-ion veri widely in width and height.

if you discharge a bare li-ion cells below 3v internal damage may occur. discharging below 3v is not dangerous, but will damage li-ion cell.

firefly and other lights that uses a metal clip to hold sammie in. larger nipple of R123 could cause a dead short.

HD45 is designed for 18650 and/or 2x CR123 primary cells. combine extra width for 18650 with kilroy spring and extra wide nipple of smaller diameter R123 could bridge center contact with kilroy spring. note if you put 2x R123 in HD45 you will kill board.

Phredd said:
Is #7, "don't over-discharge"?

I'm new to unprotected lithiums. My first Orb is in the mail. I thought the most danger was in over-discharging, because then the cell could explode during charging.

Phredd
 

hburner

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Great thread and very imformative cy.

I never divulged this bit of information, mainly becaue I knew it was my fault.

I had 2 17500 cells that I was using in series my C3. They where freshly charged and placed in the light the night before. The next day I had to go in early and was going to use my C3 (surefire) becuase the maintenence guys always shut off the lights when I go in on Sunday mornings by myself it is dark as crap in there(me and the plant manager).

Anyway, prior to leaving the house I turned on the C3 and nothing. Dead. This was beyond me at the moment. So I just grabbed my L5 and went out the door.

When I got back home I tested each cell. 1 cell was at 4.0v and the other was 0.00. ZERO? how in the heck did that happen? I still do not know. Like a complete idiot, I knew better but was hard headed and going to try anyway to recharge this cell. My MAHA would not start a charge on it. So I switched it another voltage sensitive charger and it would not charge it either. So I put it in serises charge with the other cell and after checking it about an hour later it had a charge of about 3.0v

I thought I can save this thing. I went into the living room and left it charging in series with the other battery, fell asleep and was awakend by a .410 gun shot going off in the back bedroom and my wife screaming somethings on fire.

Sure enough when I got back there the one cell had exploded and was cherry red and parts of it were going thru my computer desk, printer, and external burner. Luckily none of it got on the carpet. I put water on the red parts of it and cleand up the black crap that had gotten everywhere within 3 feet.

Just a little story to add cy's very important message, signed, anonymous.
 

cy

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Yeooooo.... glad your house didn't catch on fire and most importantly no one got hurt!!!

operator error or course, but which charger did you use to set it off?
and at what setting?

what brand 17500 cell and was it a protected cell?
got any pictures?

this makes the second documented li-ion explosion posted on CPF.

DISCLAIMER/CAUTION: I am not a battery expert nor do I pretend to be one. Please verify this information for yourself. Use this at your own risk. Not responsible for anything. Information for consumer use of loose li-ion cells is constantly evolving.

hburner said:
Great thread and very imformative cy.

I never divulged this bit of information, mainly becaue I knew it was my fault.

I had cells that I was using in series my C3. They where freshly charged and placed in the light the night before. The next day I had to go in early and was going to use my C3 (surefire) becuase the maintenence guys always shut off the lights when I go in on Sunday mornings by myself it is dark as crap in there(me and the plant manager).

Anyway, prior to leaving the house I turned on the C3 and nothing. Dead. This was beyond me at the moment. So I just grabbed my L5 and went out the door.

When I got back home I tested each cell. 1 cell was at 4.0v and the other was 0.00. ZERO? how in the heck did that happen? I still do not know. Like a complete idiot, I knew better but was hard headed and going to try anyway to recharge this cell. My MAHA would not start a charge on it. So I switched it another voltage sensitive charger and it would not charge it either. So I put it in serises charge with the other cell and after checking it about an hour later it had a charge of about 3.0v

I thought I can save this thing. I went into the living room and left it charging in series with the other battery, fell asleep and was awakend by a .410 gun shot going off in the back bedroom and my wife screaming somethings on fire.

Sure enough when I got back there the one cell had exploded and was cherry red and parts of it were going thru my computer desk, printer, and external burner. Luckily none of it got on the carpet. I put water on the red parts of it and cleand up the black crap that had gotten everywhere within 3 feet.

Just a little story to add cy's very important message, signed, anonymous.
 
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VidPro

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its funny how you say you wouldnt use a cheap charger, kinda suggesting that normal people need to plunk down $100 for a charger, with some cute brand name, and complex capacity to do things.
yet when they blow up the cells in TESTING, what do you think they use ? A High amperage hobby charger.

because these overpriced chargers need a expert practicaly to operate them Correctally, and CAN exceed the specs for a cell, mabey a expert would want to use them, but there is no need for the consumer to try and charge FASTER to be safer.

lots of these cells are tested to 5V <--- yup WAY over, to see if they will start a fire, and they do not, untill you increase the AMPerage too.

while telling people to avoid cheap chargers, that go OVER spec when charging, is a good idea. The TOO high ones need to be identified, but the current on a cheap charger is so low, that catastrofic failure is LESS likly than a improperly used FAST charger.

if people aint gonna plunk down the cash , and time , and read manuels, they are better off with a LOW amp rate, then a High amp rate charger.
look at the specs for the Caused Fires, they are always pumping in some major juice.

ID the junk, and stop the sale of it alltoghether, its not good enough to say "pull it when its green" , it should be the thing sucks send it back, dont use it.

there are a lot of good SLOW chargers, and the day you see people setting them up out back to blow up batteries, you can convince others that they will.
Wheras the high end hobby chargers Misused are what you CAN/DO start a fire with.

we need good chargers, consumers dont need FAST chargers, nothing good will come of that, and proof of that is What exactally were each Fire causing event using? High end RC fast chargers, and fast high amp laptop chargers.

if i was staging a fire event, the last thing i would use is a nano.
ID the junk , but dont increase the rate.
 
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LuxLuthor

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VidPro, you make some good points...and I agree with most everything you say. However, in reality there has not been much use or testing of the type of Li-Ion cells we are using from AW over a long time, and in larger diverse applications, chargers, and with the kind of sample size you have in the RC community with LiPo's. I don't know how long AW has been selling his Li-Ion's here, but as the cells age, there may be more problems develop with them.

I think it is very reasonable that it would be the "Hobby Chargers" that have the higher amperage which would be more likely to cause problems, but we really don't know how much of the Li-Ion problems will be related to those stronger chargers. I don't expect to see as many disasters with the Li-Ion cell users not being as likely to push their cells as compared to the RC users with LiPo, but it is fair to extrapolate with their experiences.

I suspect there are a few others who had this type of "clandestine explosion" like hburner posted...and just don't want to talk about it. We don't know what his charger setup was but it seemed to be something from MAHA and some other charger or two. It would be nice to get more specifics so we know what was used.

In the case of Norm's exploding Li-Ion cell post here, remember he only was charging a single 14500 cell with the Alin universal Lithium charger set on "2 cells" and that charger only outputs 500 mA, so it is not necessarily a high amp charging issue. The new example is apparently combined with a questionable/defective cell....but I'm guessing he was using a low amp charger.

The problem is whether people will know they have a defective cell, and then how it then behaves with even a low current charger.
 

SilverFox

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Hello VidPro,

Here is the reason people move up to more powerful chargers for Li-Ion cells...

To keep track of things, you need to attend to your charge. A good charge rate is around 0.5C - 0.7C. The maximum charge rate is 1C. At 1C it usually takes an hour and a half or two hours to complete the charge. At 0.5C, this time is extended.

Some people have lots of time and can attend to their charging all day while charging at low rates. Others, prefer to spend a couple to three hours charging, then they have other things they want to do.

I am charging an 11.6 Ah Li-Ion battery right now. Charging at 10 amps means that the charge will be finished before I am ready to go to bed. If I were charging at 500 mA, it would take around 32 hours. I am not staying up that long to baby sit the charge.

Now, when I go to charge my 330 mAh or 600 mAh cells, I set things up a lot differently, and charge at lower rates. It is nice to have the capability to also charge large batteries when you need to.

I think the problem is that people jump on the Li-Ion bandwagon without thinking the whole thing through. People are interested in a lightweight light that is very bright and that draws them in. All of the sudden they have a light that is using Li-Ion cells, now they have to figure out how to recharge those cells.

I believe this is what LuxLuthor ran into. Fortunately, he is taking the time to learn about Li-Ion chemistry and is proceeding cautiously while he is figuring things out.

Slow charging has its place, but it isn't a universal answer.

Tom
 

cy

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most may not realize it, but we on CPF are on the bleeding edge of consumer use of loose li-ion cells.

information concerning safe use of loose li-ion cells is still constantly evolving.

I'm not a battery expert, nor do I pretend to be one. but I do know who the battery experts are. IMHO Silverfox, Newbie and JS are some of the most knowledgeable folks around.

due to the bewildering combinations possible with loose consumer li-ion cells and chargers. safety with li-ion cell use has to start at the cell level.

Meaning protection needs to be at cell level in the form of built-in overcharge protection for loose consumer li-ion cells.

loose bare li-ion cells are originally meant for professional battery pack builders who will place protection circuits in final product.

when you purchase loose li-ion cells from US companies. typically requires signing off of safety disclaimers. here's one Tenergy uses http://www.all-battery.com/datasheet/TenergyProductSafetyandUsageAgreement.pdf

VS overseas li-ion suppliers require no such disclaimers. for all practical purposes, they operate without liability for possible accidents.

this is a good thread for information about DSD and new Pila chargers. https://www.candlepowerforums.com/threads/130249&page=1&pp=20

can you pick out 14500 li-ion cells from identical looking AA NMH cells?

14500 cbp.JPG
 
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VidPro

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LuxLuthor said:
In the case of Norm's exploding Li-Ion cell post here, remember he only was charging a single 14500 cell with the Alin universal Lithium charger set on "2 cells" and that charger only outputs 500 mA, so it is not necessarily a high amp charging issue. The new example is apparently combined with a questionable/defective cell....but I'm guessing he was using a low amp charger.

The problem is whether people will know they have a defective cell, and then how it then behaves with even a low current charger.

it might put out 500ma, but then it was at 7.2V, and it probably had a much higher voltage differential than intended, and might have pushed more like 750 or 1000ma.
but indeed that is a good example. doesnt relate to trashing a little weasily nano charger that ONLY charges to a max of ~4.2, and would not have that problem. those types of chargers wont even go to 36V at 4amps :)

I have charged "defective" cells for DAYS, and DAYS, with them heating up, at .4-.5C rates, and they heat up. this particular set of cells was trash from age, and deep discharge, and was heating up, but keeping the rate low, i could not get multiple cells to even open up, let alone fire.
 
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VidPro

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SilverFox said:
Hello VidPro,

I am charging an 11.6 Ah Li-Ion battery right now. Charging at 10 amps means that the charge will be finished before I am ready to go to bed. If I were charging at 500 mA, it would take around 32 hours. I am not staying up that long to baby sit the charge.

Slow charging has its place, but it isn't a universal answer.

Tom

in the same sence while i was slow charging HUGE D cells with no problems for weeks on end and now for years, the first time i handed it to a "shultz/triton" user they slammed 1C into it and had a massive fire in "a few minutes" (thier words).

it isnt a universal answer at all, experts , and people who Learn everything they need to know, indeed SHOULD be using a great charger like that. but from what we have seen, the average person and the person having a lot of FUN :) can have more problems fast.

-----------------------------------------------------

reguardless , its like this with everything, sombody plunks down 250$ for a light, a charger, a car, some knife, some cool gadget, and EVERYONE should do the same thing. so just for the practicality of plunking down 250$ everytime somone on a forum thinks its the "best thing in the world", WHEN its great for experts, and people in the know, and people with to much money.

its not a reason to trash every other item out there that costs 1/12th that and can do the job.
meaning my 1litre car , would never pass the muster at a monster truck convention, but it still leagally does what any car can do, and it aint got a scratch on it :)

there are some people who overclock thier 2500Mgz Cpu to 5400Mgz, dance all over the forum telling how wonderfull it is. but the rest of the people following thier advice, tried to return thier fried $200 processor :).

sometimes experts forget how much time and effort and thought went into thier knowlege, and how dum the rest of us can be.
 
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VidPro

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take another example, just for the sake of examples.
people had been charging ni-mhys for some 20 years, then along comes the "best charger in the world" those 900 and 9000 untested digital masterpieces. plunking down huge sums, charging at high rates. suddenly things are melting .
set these digital items incorrectally, or use them evil crap batteries that everyone in the world owns, and it Could be a bigger problem, than the "crudiest charger in the world".

i am not saying that ANY of it is "bad" , but that "improvements" often have as many ramifications, as the old stuff. so recommendations for moving way up in a world that you dont yet understand, are not going to "solve" problems by themselves.

one more point to the side, wasn't it high end RC chargers that were doing SEIRES charging without balancing? if these companies and thier chargers were so great of items, why did it take them so long to get balancing taps?
To compare what THEY DID, to your simple little parellel non-series charger, is crasy, it was thier seires charing without balancing, by those brand name chargers that caused loads of the problems that everyone gets all worried about.
ok Charring, charging , same differerance :) you get the idea.
 
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uk_caver

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VidPro said:
in the same sence while i was slow charging HUGE D cells with no problems for weeks on end and now for years, the first time i handed it to a "shultz/triton" user they slammed 1C into it and had a massive fire in "a few minutes" (thier words).

I was thinking about what various people have written regarding overcharging, and was wondering if it's possible that extended low-rate overcharging might well not be enough to blow a cell, but could put a cell in a state where it was then particularly vulnerable to high-rate charging it might normally not have problems with?
 

VidPro

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uk_caver said:
I was thinking about what various people have written regarding overcharging, and was wondering if it's possible that extended low-rate overcharging might well not be enough to blow a cell, but could put a cell in a state where it was then particularly vulnerable to high-rate charging it might normally not have problems with?

overcharging CAN indeed cause the same issues that over-discharging can, set the cell up for overheating when its charged.
overcharging even very very slowly, for a Long time will puff a li-poly, or open up a cell.

but most of the junk china slow rate chargers were Not going over 4.25, ever, green light or not. some are based on cheap protection curcuits.
and really ALL the batteries should have thier OWN protection, reguardless.

they wouldnt even SELL me cells , long ago, untill i defined what type of protection i would use on them. Seperated unprotected cells are for pack replacments, and pack making, packs that would have not only protection but thermal disconnect of some sort.
but heck protection curcuits are 2$ what was the problem? other than hotwires :)

if some of them are going +-.05v of 4.20, then they are still in spec, if they are going to 4.35v, then we should be saying "Dont Use it" if its a problem. we know of one that people claim that is what it does, can we call a hoe a hoe?

besides who puts the name "FIRE" on a li-ion battery or charger anyways :) thats just asking for it.
 
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