Li-ion batteries

Lets talk batteries OK , seems some folk probably know Jack about there battery pack

We all are aware that Li-ion can flame / explode right , watched enough of them on Youtube and think we know everything there is to know right .
Even watched the ones where 18650 are nailed , shorted etc .
And after watching all those vids one probably thinks that they are relatively safe ...

Well , they still explode ( Li-ion ) , quite a few flashlights have gone the way of the hand grenade , and last year quite a few chargers were blown up as well .

Not all li-ion are the same , the quality varies greatly . Most people buy the cheap Chinese Fire Brands , and there is a reason these batteries are cheap , they are bottom of the barrel . I have tested and owned enough of them , and some are so bad I have thrown them away after testing as they were simply to dangerous to own ( But what do I know ) .

Now , what makes a bad battery , resistance .
Resistance to discharging , and resistance to re charging . Obviously there is a reason for the resistance but we don't need to get into that . ( But its a good indication of battery quality )
I have tested batteries that can do a 5A discharge , and I have tested batteries that can not do a 2A discharge let alone 1.5A .

So imagine how much stress a battery that cant do a 1.5A max discharge would be in , if it were put into a high powered application ( High current draw ) .. Think about it like this , the red line on your engine is ? 6000RPM , so how long would it last if you drove around with it doing 10,000RPM .

This is why testing , and using the appropriate battery for the intended application is very important . ( Im not going to get into cell matching now either ) .

Here is some useful information : Discharge levels ..
Li - ion will degrade faster the more you discharge the battery , and what I mean by that is :

If you recharge @ say 3.8v , verses say running the battery down to 3v or the safety cut out ( most flashlights these days are 3v cut out ) ..

The battery recharged at 3.8v will suffer far less internal degradation than the battery depleted all the way .


Now , when batteries get old enough , or degraded enough they begin to degrade internally and develop internal shorts ( worst case ) ..

Now these internal shorts are not catastrophic by themselves , but if you have a older or a super cheap charger , and the battery suffers an internal short while on the charger . Then you need to understand that the charger will contribute power to the short , so the battery is drawing external power in its attempt to self destruct . ( SO its not just the battery )

In a worst case scenario the battery will flame or explode , and there is already a documented case of a house being burned down because of the overnight charging of li-ion batteries .

Charge rate : I love this one ..
A battery is at its most vulnerable to damage when it is fully depleted .
A high charge current is bad for batteries in the sense that the lower the charge current , the batter for the battery .

All you need to do is go on youtube and see all the li-ion flamers , cars buggies and planes .. Why ?
Because folks are drawing huge amounts of current from the batteries ( BAD ) , and then quick charging with large currents ( BAD )
Cells are failing , and when a cell fails a situation of revers charging can occur or a internal short in the cell , and the entire battery pack goes up .

Cell failure : Any battery can fail in a high current situation , and if it is part of a pack , then reverse charging can occur ( BAD - flame / Boom )

At what point can a 18650 fail .. I have noted several batteries failing @ 3Amp current draw . What do I mean by fail ..

Hobby charger is drawing 3A and after about 3 minutes the discharge ends with the hobby charger reading 3v for the voltage level ..

Was 4.2v , rated at 2600mAh and after a few minutes is reading 3v , that is a battery failing big time , and in a big flashlight , could make for a hand grenade situation .

So , high discharge is bad for a battery ( stress ) , high current charging is bad ( stress ) .. Over discharging ( BAD ) , and the fact that we don't have more flame/boom events , shows how tolerant Li-ion is to abuse . But I would still not call the battery safe because stuff can happen . In a worst case scenario it can blow something up , or burn it to cinder . ( That's not safe )

Don't like my explanation : ( Tough )
DO your own research , its your life and your responsible for it !

To date I have only noted Cells failing a 3A discharge , none have failed a 2A discharge ( Cheap batteries ) .. That does not mean they can not fail at a lower level of discharge . ( My own personal observations from battery testing 18650 ) Smaller batteries ( 16340 - 14500 ) I only test to 1A discharge .

It would be interesting to have a box of cheap batteries and seeing at what point the batteries fail .. ( As this would be the DANGER point )
All you guys running multiple batteries , I hope your testing and matching the batteries !

That's it for me : Got questions , hit google !

I'll just use Lithium Iron Phosphate batteries then. Much safer.

old4570 said:

Li - ion will degrade faster the more you discharge the battery , and what I mean by that is : ...The battery recharged at 3.8v will suffer far less internal degradation than the battery depleted all the way .

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Um... have you SEEN the discharge curve for a lithium cell?



You're gonna throw away SIXTY PERCENT of the battery capacity just for the sake of babying it?

"A ship in port is safe. But that's not what ships are built for."
- Grace Hopper

old4570 said:

there is already a documented case of a house being burned down because of the overnight charging of li-ion batteries .

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Billions of lithium cells have been charged since their advent. I'd say one out of a billion is a good track record. Why the fear-mongering? Why is that necessary? You've got a better chance of being struck by a meteor than being killed by a lithium cell.

old4570 said:

A high charge current is bad for batteries

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And driving over 50mph is bad for gas mileage.

I want PERFORMANCE, and I will not sacrifice performance for fear of slightly reducing the life span of a <$9 part

old4570 said:

folks are drawing huge amounts of current from the batteries

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Do you have any other suggestions on how to power a quad copter? Good luck taking off at 1 amp.

Another consideration is fakes. It's hard to know who is selling fakes and who isn't and as we all like a bargain we may be more likely to buy fakes.

I found a list of authorized Efest shops in USA and Europe. (which I used when buying some Efest IMR 18650 button tops)

Cyparagon said:

Um... have you SEEN the discharge curve for a lithium cell?

Dud , I used to make them , chart them etc ( Discharge charts ) .. Been testing batteries for over 5 years ..
That chart don't mean squat if a battery FAILS due to high discharge .. If you knew anything at all you would know that ..

You're gonna throw away SIXTY PERCENT of the battery capacity just for the sake of babying it? Really ? I didn't know one was throwing away anything at all , how much bother is it to charge your batteries ? For me its no bother at all .. Ok I own over 100 flashlights , so I have plenty to chose from , but still . I charge my batteries around 3.8v because I want to , I want to baby them , I want them to last longer , I don't want them to go Boom on me , and who cares about how much you are using ? Your not loosing money or anything , that's a rather ???? statement , obviously you feel like being the monkey on some ones back . Does it make you feel good raggin on people ? Your POV must be so important to you .. How about starting your own threads ? Let people have a go at you ?

"A ship in port is safe. But that's not what ships are built for." Li-ion were not made to go Boom either
- Grace Hopper



Billions of lithium cells have been charged since their advent. I'd say one out of a billion is a good track record. Why the fear-mongering? Why is that necessary? You've got a better chance of being struck by a meteor than being killed by a lithium cell. Killed , did I say that ? But Li-ion has been blamed for bringing down Aircraft so ? - Loss of life ? Certainly a Ban on Li-ion for air transport or did you miss all that ?

Drink driving kills - Drugs are bad for you - smoking kills etc and etc ... Sweet lord - Its called knowing what your doing - Want to be a dumb F , not my problem



And driving over 50mph is bad for gas mileage. Really was never about mileage was it - That IQ thing again

I want PERFORMANCE, and I will not sacrifice performance for fear of slightly reducing the life span of a <$9 part
Yeah , and that's where it gets interesting



Do you have any other suggestions on how to power a quad copter? Good luck taking off at 1 amp.

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JFK U like taking things out of context don't you .. Got nothing better to do , don't have any friends .. Don't tell me you could coach a football team better than any NFL coach right !

The RC boys use flame proof bags now because Li-ion fires are so common , the more performance we push out of Flashlights the more issues we are likely to see , even the Vapor boys have had battery problems from using cheap nasty batteries ..

Take from this what you will , but why would you be such a dick about safety ? Is it wiser to avoid problems , rather than go sucking for them ?

I guess ignorance is bliss , what you don't know wont worry you ..

A friend of mines parents house burnt down from a LiPo fire charging a battery for an RC chopper near some laundary in a garage. I always treat Lithium cells with respect and charge the quadrotor cells in a LiPo bag (not convinced they're that much of a help) or the fireplace. Few people realise their android tablets come with a nice flat 4Ah+ LiPo in the back. But at least they are charged way below 1C.

It's a balance between performance and safety. People will argue for either end of the scale as seen above, but for most they will sit somewhere in the middle. But it is good to be aware that the scale exists and make informed choices.

clansley said:

Another consideration is fakes. It's hard to know who is selling fakes and who isn't and as we all like a bargain we may be more likely to buy fakes.

I found a list of authorized Efest shops in USA and Europe. (which I used when buying some Efest IMR 18650 button tops)

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Yes the good old fakes .. 5 years ago the fakes started showing up , and now , there are more battery flavours than I can count and most of them are garbage .. Stick to the Japanese cells , and you should be fine . Single cell lights are safer than multi cell .. But then everyone wants that monster light these days , not getting 5000Lumen goodness ? Just go on Ebay and buy one , and they often come with garbage batteries . I dare say we probably don't hear about 90% or more of incidents , just like we don't hear about every car accident or every heart attack etc .

Any one know if you need to worry about IMR versions? (all my batteries are IMR) Should I get a bag to put my charger into?

Don't these bags reduce air flow and therefore cause cells to heat up quicker (although I guess it will just mean the charger will cutout more frequently and just charge them slower?)

Bags are generally for hobby charging cells, where the battery is separate from the charger. As you observed, putting a charger in a bag wouldn't be a good plan because of the heat generated.

tttonyyy said:

A friend of mines parents house burnt down from a LiPo fire charging a battery for an RC chopper near some laundary in a garage. I always treat Lithium cells with respect and charge the quadrotor cells in a LiPo bag (not convinced they're that much of a help) or the fireplace. Few people realise their android tablets come with a nice flat 4Ah+ LiPo in the back. But at least they are charged way below 1C.

It's a balance between performance and safety. People will argue for either end of the scale as seen above, but for most they will sit somewhere in the middle. But it is good to be aware that the scale exists and make informed choices.

Click to expand...

You can have your cake and eat it . I fly 450 class helicopters , run 2 chargers , and have over half a dozen battery packs . And I charge my batteries ever so slowly @ 1Amp ( Balance charge ) . I always balance charge at a slow rate . Because the packs are made up of 3 cells ( mine are ) and the cells are not matched ( Matched for discharge ). At the end of the flight the voltages are not always even in the pack . There is just enough variation that if you did not balance charge , you could have a larger variance at the end of the charge . As the pack voltage is a combination of the 3 cells . And this variance over time could become a serious issue . So always balance charge your RC packs . Some people run maybe one or two packs and treat them hard .. I never do that . Hence I run more packs and baby them as much as possible .
Now the really high performance Boys know how important batteries are and build there own packs , they do this to match cells . They test the cells individually and then combine them to make packs with the cells that test the closest . They been doing that since 1/12 scale electric took off and that's a long time ago . This is nothing new , its just that a new generation needs to learn what is generally some rather old know how , and yes I have been around that long

clansley said:

Any one know if you need to worry about IMR versions? (all my batteries are IMR) Should I get a bag to put my charger into?

Don't these bags reduce air flow and therefore cause cells to heat up quicker (although I guess it will just mean the charger will cutout more frequently and just charge them slower?)

Click to expand...

Eeer , buy a better charger ! or Charge outside ..
Lots of people use the old tin lunch boxes and the like ..
But don't seal it ..

Xtarlight.com makes some advanced chargers .. And over time they will only get better .. If your still using the old Trustfire TR-001 , it might be time for an upgrade ..

old4570 said:

Eeer , buy a better charger ! or Charge outside ..
Lots of people use the old tin lunch boxes and the like ..
But don't seal it ..

Xtarlight.com makes some advanced chargers .. And over time they will only get better .. If your still using the old Trustfire TR-001 , it might be time for an upgrade ..

Click to expand...

I have a NiteCore Intellicharger i2 2014 (review). which I believe is a good charger.

clansley said:

I have a NiteCore Intellicharger i2 2014 (review). which I believe is a good charger.

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Yes , that should be a good charger .. Don't own one as there were so many counterfeits going around at the time I wanted one .
+ I have a drawer full of chargers .

It seems there are fake everything!
Even the charging bags:

clansley said:

Any one know if you need to worry about IMR versions? (all my batteries are IMR) Should I get a bag to put my charger into?

Don't these bags reduce air flow and therefore cause cells to heat up quicker (although I guess it will just mean the charger will cutout more frequently and just charge them slower?)

Click to expand...

There are IMR and IMR .. I have a IMR that's around 6 years old and still going strong ( Been babying it ) ..

All batteries need to be treated with respect ..

No don't put you charger in a bag , it needs convection cooling ... The circuits inside can get rather toasty .. Why I sometimes open up the chargers and drill extra holes for cooling ( moving air )

If your really concerned , charge outside ! - Do you have a shed / garage ?
A porch , put the charger in a metal box outside where rain cant get at it ( why beg for problems ) and it should be sweet . If it goes boom , it will do so in a metal box .. Just don't put a lid on it - needs air for cooling .

One really should get to know ones batteries ( multi meter ) , where you have discharged the battery ( Voltage ) , and the termination voltage after charging ( Give it an hour before taking a reading ) ..

A decent charger should take a good battery to 4.2v , and when it settles it may be 4.18 or 4.19v depending on internal resistance ...
Older batteries and batteries that are nasty ( cheap ) may end up around 4.10volt or less .. ( Less is not good if the charger terminated at 4.2v )

Now a lot of people get ants in there pants about over charging , and its not really a huge deal unless its a large amount . And then its very dependent on the initial quality of the battery .
If you charge to 4.25v its not the end of the world , if you charge to 4.3v you may want to buy a new charger . If you charge to 4.5v , then you might have a issue you need to deal with ( oh dear ) . Now you might think no way ! 4.5v your dreaming . Well If I am so was my multimeter . I took a Panasonic to 4.5v and that was over 2 years ago and that battery is still going strong ( no I don't charge it to 4.5v - That was a ooops , because stuff happens ) . It pays to keep an eye on starting voltage ( Battery before you charge ) and termination voltage .. This way you can monitor the health of your battery .

We missed a bit of talk about the relation between Internal resistance-voltage sag-capacity, e.g sometimes the IR causes sag and then you need XXXX voltage to run whatever, and because of the sag and voltage need of the flashlight you are sort of going to loose capacity on the higher drain applications, unless you use the high IR batts for low load applications then you will still get a good capacity out of them,
Dont forget protection circuits too! they are quite common these days!