protected vs.unprotected rechargable Li-ion safety

For single battery use, does it matter? For instance, using one 14500 in a chopped down 1AA miniminimag. Is it inherently safer to use a proteced battery rather than an unprotected one?

Where, as long as you charge the unprotected battery when the light dims and don't dishcharge it to 2.7 volts you'll be ok. And you use a DMM to monitor it while charging so as not to ovecharge it you would also be fine.

But with the protected cell you would not have to be as diligant for discharge and charging.

Clarification and thoughts appreciated.

basically.
protection is there for great reasons, shorts shouldnt start fires with them.
overcharge will vent gass, and start fires (most cells though also have anode disconnect)
over discharge ruins them, ruined they can get HOT when charging, start problems again.

if you can "insure it never overcharges" with a DMM then your a miracle worker /ubbthreads/images/graemlins/smile.gif
because when i dont have protection specifically ON a cell, it takes my entire LIFE to insure that it doesnt go over, because that Last Little Bit , is a very fast occurance, its not much of its capacity.
If something critical happened (in my normal existance) while i had one being WATCHED, something critical would have happened to it before i got back to remember it was there.

i could get away with dillegence in discharging, because the capacity is GONE when your supposed to stop. but then you still have accidental discharge.

with White leds, there is the fact that the gate will stop triggering and it wont discharge Totally till it cant be charged, but you still would lose some of it.

i hate protection, for example you cant hotwire a li-ion, because protection stops excessive discharges like 4A for the 18mm type cells.
but what kind of runtime are you going to get when you ram it for more than 2c anyways :-(.

If i had a CHOICE, i would FAR prefer protection.
i would never CHARGE without a cutoff
i will get away without discharge protection in parellel White LED setups.

the best thing they did, was put protection on each cell, so we can get ON with them becomming more consumer oriented (even for flashlights), once they become a consumer item, the improvements will ensue.

if your trying to run a RC off them at 10C i imagine they will either have some protection that will allow for really cranking on it, or they just avoid protection for just the discharge. but what do they care if they have to replace everything for each 100 hours of use /ubbthreads/images/graemlins/smile.gif thats RC for ya anyways

Hello Mike,

Using a "trusted" charger will eliminate most of the safety problems with Li-Ion cells. Most problems occur during over charging.

Over discharging is also a problem, but it usually manifests itself in reduced capacity and reduced cycles.

The protection circuit allows another layer of safety, at the cost of capacity.

If safety is a top concern, use a protected cell along with a quality charger in a light that stops working at 3.0 volts.

I use several lights with unprotected cells. I charge them frequently (it works out to once a week for my use), and I pay attention to how much use they get. No problems so far.

Tom

Hello VidPro,

Your assessment of RC battery packs is a bit optimistic...

They are hoping for 150-200 cycles when running at 10C. That works out to 30-40 hours...

Tom

[ QUOTE ]
SilverFox said:
Hello VidPro,

Your assessment of RC battery packs is a bit optimistic...

They are hoping for 150-200 cycles when running at 10C. That works out to 30-40 hours...

Tom

[/ QUOTE ]
so do they have protection (even available) for those kinds of high discharge rates?

Hello VidPro,

No.

Tom

thanks, i am still waiting for the Mega protection curcuit cheap. like 10A in , 20A out.

[ QUOTE ]
SilverFox said:The protection circuit allows another layer of safety,

[/ QUOTE ]

I agree for batteries (more cells), as balancing is very important.
Not so for single cells: All of this circuits need a connection in between the poles at very, very restriced space and add IMHO as much risk as they avoid (I'll tell that all the time and it was just proved in another thread).
I just use chargers were I know hat they do and prefer lights with do the same (that means for single cells, I prefer that the light takes care of deep discharge protection).
And shortages are better avoided through design and care.

I also avoided fuses on many of my devices, as they add complexity and sometimes bad contacts.

Of course it always depends on the situation....

Re: protected vs.unprotected rechargable Li-ion sa

I just had an sn2 clone stop working after over 2 hours running with a pair of protected "AW" 18650 2200mah cells.

Re: protected vs.unprotected rechargable Li-ion sa

3rd shift,

' stop working ' means the protection circuit kicks in due to low voltage cut-off or.... /ubbthreads/images/graemlins/thinking.gif

Re: protected vs.unprotected rechargable Li-ion sa

I hope someone's still reading. Two fast questions:

1) My chargers (Nano and JSBurly's) both charge my protected and unprotected cells to 4.3v. Have I damaged the cells by allowing that?

2) Tonight I accidentally shorted one unprotected cell for about 4 seconds until I noticed the heat in my hand. Should I stop using it?

Thanks.

Re: protected vs.unprotected rechargable Li-ion sa

[ QUOTE ]
HaulinLow said:
I hope someone's still reading. Two fast questions:

1) My chargers (Nano and JSBurly's) both charge my protected and unprotected cells to 4.3v. Have I damaged the cells by allowing that?

2) Tonight I accidentally shorted one unprotected cell for about 4 seconds until I noticed the heat in my hand. Should I stop using it?

Thanks.

[/ QUOTE ]

1) i dont think so, they certannly DIE completly at 4.5 i have tested some at 4.4 before i knew better /ubbthreads/images/graemlins/blush.gif, and they worked great. Note: Very very Slow

the overcharge, the cell itself going over the voltage, causes a pressure rise, which can activate the pressure disconnect that is a safety feature that is "required" to sell li-ions (can cells) in america. they wont work after the safety disconnect activates (ever again).
in the bagged cells they will expand/puff up and be ruined, when overcharged.

in my opinon 4.3 is just fine, i am testing 4.35 in controlled tests (Very Slow) and wont know how it effects the longevity of the cell, till about the year 2008 , i will get back to you then.

the way protection works, it could kick IN at 4.25 and still get the cell a bit higher than that, nice little safe place, with sufficient charge.

the protection curcuit that i am playing with, is at 4.35, and aparentally was a "last chance" type of cutoff. although so far it seems to work great.

the nano (from what i know) is voltage regulated, it could be off a bit here and there , but it should get to its max voltage very SLOWLY, so that should be a good thing. and TO ME, that sounds ok still.

if you wanted to, you could put a tiny load across, and read the max voltage, like a resister of some sort over 500ohms mabey.

2) rechargables will really heat up when shorted, and a wire across them as a dead short will go balistically hot, its not great to keep discharging a cell really really fast (that is basically what you did) but its not going to kill it instantally (unless the anode breaks, or it ketches fire). and it should present no safety issues, if it survived.

which leads to , if a li-ion canned cell heats up when you charge it normally, it might be junk. if a li-poly heats or bulges more than normal when you charge it normally , its probably junk.

from what i know now . . which is never much, your totally set to go.

if you shorted out a li-poly pack, you could heat and break the anode internally, and start it on fire.
a li-on canned cell is more likley to break the annode above the electrolyte roll. but you still could have cause a fire internally (whoosh).

and
a protection curcuit would normally only allow so much "discharge" at a time, so if you shorted out a properly protected cell it should just disconnect at its high current cutoff point.

Re: protected vs.unprotected rechargable Li-ion sa

VidPro, thanks alot for taking the time to give me such a thorough anwer. I feel better about using that battery again.

Unfortunately, the cell I shorted is unprotected and I had read somewhere about damage to the battery increasing the likelyhood of future internal copper formation that could cause an internal short and fireworks, so I needed some reassurance. I'm gonna try to pay more attention from now on /ubbthreads/images/graemlins/smirk.gif. I actually put the battery in a bucket outside for a while until I felt safe checking up on it. It was Hot.

Thanks again!

Re: protected vs.unprotected rechargable Li-ion sa

[ QUOTE ]
HaulinLow said:
VidPro, thanks alot for taking the time to give me such a thorough anwer. I feel better about using that battery again.

Unfortunately, the cell I shorted is unprotected and I had read somewhere about damage to the battery increasing the likelyhood of future internal copper formation that could cause an internal short and fireworks, so I needed some reassurance. I'm gonna try to pay more attention from now on /ubbthreads/images/graemlins/smirk.gif. I actually put the battery in a bucket outside for a while until I felt safe checking up on it. It was Hot.

Thanks again!

[/ QUOTE ]

wait just a darn minute /ubbthreads/images/graemlins/grin.gif
did you short it for a while, and get heat, or short it and it KEPT heating up.
because if it continued to go thermally wild on you AFTER you shorted it, then you damaged it , something internally connected.

if you were rushing it to a protective containment , because it was internally shorted, and it went crasy, thats different.

if it is internally shorted, or even gained a resistive increase, you could test it and see if it was still discharging itself 0V. if it still has juice then charge it safely, and see if it self discharges to fast.

Re: protected vs.unprotected rechargable Li-ion sa

VidPro, you are like my guardian angel, man. I may be in serious jepardy if you ever leave the forums! /ubbthreads/images/graemlins/wink.gif

The cell did not continue to heat after I removed the shorting clip. I just didnt want to have to explain how the rug and curtains burst into flames to my lady and decided the bucket was the the appropriate proverbial ``ounce of prevention``. By the way, what would be the metric conversion unit for the ounce of prevention?

Im going to have to test the resistance as you recommended. I dont have a charger sophisticated enough to allow me to slow the charge rate, or any resistors to play with. I will charge it up to 4v,give it a week, and see how it is holding up.

I appreciate your going out of your way to protect my property and posterior.

Re: protected vs.unprotected rechargable Li-ion sa

28 grams of prevention :-D

i have shorted half dozen LiONs of course by accident in the process of building lights.. mostly when introducing a short in the head of a nano... the battery gets very warm very quickly... and if i charge it at a normal rate (C/2) afterwards.. it will not charge fully.. i mark them with an 'x' so i won't end up selling that battery and use it for testing. when i charge them at C/4 they usually come right back to a full charge but i do keep them marked so i can keep track.

i shorted a LiPoly flatpack battery a while back when i dropped something on my bench across the leads.. got a nice loud pop when something melted and apparently it made really good contact and probably pulled 50+A internally.. the battery read zero volts immediately.. i drew a frown with x x for eyes like the cartoon and kept the battery... it puffed up over time (like 2 weeks) and still is inflated.. i keep it as a reminder... which apparently still is not a good enough one... yesterday i dropped an x-acto knife on my OTHER lipoly battery and got to smell some tape on my bench start fire while the entire cathode lead turned bright orange... this time the connection was not as good.. the battery survived.. but i don't think it holds a full charge anymore.

with some of the LiON 'events' of late.. when i will charge batts in an 'iffy' charger... i'll leave it on bare cement w/o anything flammable too close if i have to charge it unattended.

I had over discharged some cells.. and stupidly tried to charge them in series... big no-no... one of them died in the charge process and became very unhappy, but only amounted to leaking something out that melted the ouch... fivemega 3x168 irreplaceable battery holder... i didn't even see any residue on the table (wood) below it, so that was odd.. the other two batts charged to 4.0 before the dead one opened.. and afterwards i could charge them to a full 4.15.

I just checked that 'shorted' bat and it charged to a full 4.15 just now.. mebbe 'before incident' it may have charged to 4.18 or something but that's not 'worst for wear'...

-awr

Re: protected vs.unprotected rechargable Li-ion sa

right if you charge un-protected in series a imbalance in the cells could have one higher, and another lower.
so even if you had a set max voltage for the series, there is nothing to stop ONE in the series from going over.

---3.7---4.6---

same basic thing for discharges un-protected in series, one could still be at say 3.6 and the other being deep discharged at 1v or lower. a luxV or a series set of luxI-III would just finish triggering then, so mabey it wouldnt KILL it completly, but it wouldnt be good.
a Driver curcuit that takes the batteries all the way down or incadescent, though would totally reverse charge the low one, and poop on all your plans.

---3.6---1v---

a protection for the series , basically gives each battery its own cutoff. BUT /ubbthreads/images/graemlins/smile.gif a lot of series protection curcuits suck bad, because of thier design (or did a few years ago).

parellel is much simpler.

Re: protected vs.unprotected rechargable Li-ion sa

It is reassuring to know that Im not the only one who goofs with these even though I know to watch them.

andrewwynn, I love the design of the minimighty. I hope to own one someday. Keep on impressing us, sir!