explosion when charging li-ion cell, Universal Smart charger set on wrong voltage

[SilverFox]

Re: A Cautionary Tale

Hello David,

There is no feed back loop that tells the charger how many cells it is hooked up to.

Tom

 

[Kevin Tan]

Re: A Cautionary Tale

I'm glad you and your property are OK !

So much for the "smart charger" part. If it really was a smart charger, it wouldn't be relying on YOU to flick a switch.

It seems "convinent" that Li-Ion manufacturers are making AA, cr123 and other sized batteries, but I can see how maybe it's not such a good thing.

LB, I beg to differ here, I prefer to think that blame should fall where blame is.

In this case, the fault of the operator ( whom has stated that its a lesson learnt )
- for not checking the charger is charging the proper cell or cells,
- for buying an unprotected lion battery and ignoring the safety issues
- for not buying a protected lion which wud have avoided the problem.

So learnt as much as possible about whatever batts you play with and understand the limits of the beast. The beast bites back!!!!

 

[jusko]

Re: A Cautionary Tale

Isn't it more safe if the charger charges cells in parellel ? No switch is needed.

 

[SilverFox]

Re: A Cautionary Tale

Hello Jusko,

Yes.

However, it may take longer if your charger only has one charge rate.

Tom

 

[David_Campen]

Re: A Cautionary Tale

Hello David,

There is no feed back loop that tells the charger how many cells it is hooked up to.

Tom

I am not assuming any feedback loop. If the charger is going to charge batteries in series and one of the batteries in the series is removed then you have an open circuit and none of the remaining batteries will see any voltage. This is just like Christmas Tree lights that are wired in series; if you remove any light in the string then none of the others will light.

 

[paulr]

Re: A Cautionary Tale

Pairs of li ion cells should normally be charged in parallel, not series.

 

[VidPro]

Re: A Cautionary Tale

why didnt the anode disconnect function? the one that is supposed to be on the battery when they are sold in the US.

why didnt the charger know there was that battery in it? heck a ni-cd charger knows when a alkaline battery is in it. 2x charging series li-ions at 8.4 alone isnt fully safe without seperate battery protection.

dont seem like the user is to blame to me, both of the above items should prevent that from happening, seems like a really flipping dumb charger, and a battery not to spec.
what kinda cheap junk are they selling us, when it takes a 2$ chip to keep this from happening.

i could see it from a triton, or some expencive battery charger accepting expert user parameters for charging, but it looks like a drop in charger for normal humans.

 

[matrixshaman]

Re: A Cautionary Tale

Glad you are okay Norm. My Opinion : A charger should not be able to blow up a battery simply because of operator error - to err is human and things like chargers should not so readily be able to cause exploding batteries by a simple mistake of the switch setting. Just my opinion - a different design for these chargers COULD save serious injury. Just caught the above post while I was writing - AGREE - it's not a 'smart' charger - and a sensing circuit could prevent the problem...... charger

 

[65535]

Re: A Cautionary Tale

Although cheaper I find series chargers to be less reasuring.

 

[eebowler]

Re: A Cautionary Tale

:eeew: :grouphug:

 

[AndyTiedye]

Re: A Cautionary Tale

That charger is really made for charging battery PACKS (which are supposed to have their own protection).
It obviously has no way of balancing the charge, so the cells had better be well-matched.

 

[jimjones3630]

Re: A Cautionary Tale

Glad to hear you are ok. Sounds like the kind of mistake that anyone of us could make.

Maybe built in charger protection should or should not be required. If so, the cost will certainly be passed on to the buyer.

If not, I'm certainly going to pay attention when I charge my unprotected cells in what's probably the same charger you have.

As pilots say any landing is a good one, maybe any story you live to tell is a good one aswell. Jim

 

[Norm]

Re: A Cautionary Tale

That charger is really made for charging battery PACKS (which are supposed to have their own protection).
It obviously has no way of balancing the charge, so the cells had better be well-matched.

I can be used to charge a single cell otherwise what's the use of the single cell setting. I'm inbetween chargers I just sold my DSD and am waiting on an UltraFire charger.
Norm

 

[SilverFox]

Re: A Cautionary Tale

Hello David,

The way that charger works is that it raises whatever is connected to it to whatever voltage you select.

If you select 1 battery, it raises the voltage to 4.2 volts. If you select 2 batteries, it wants to raise the voltage up to 8,4 volts, and so on.

The connection is made because you hook the + lead to the + of the battery(s) and the - lead to the - of the batterie(s). Unlike your Christmas tree light example, when the battery is hooked up it completes the circuit.

If you hook up an Alkaline cell, it will try to raise the voltage of the cell up to 4.2 volts times the number of cells that you have selected. If you hook up a NiMh or NiCd cell it will try to raise the voltage of the cell up to 4.2 volts times the number of cells you have selected. It is "smart" because it doesn't exceed 4.2 volts/cell, but you have to select the right number of cells and make sure you are charging the correct chemistry.

Some RC chargers (like the Schulze, Triton, and ICE) have a voltage check that sounds an alarm if the voltages don't match up. If I try to charge an over discharged Li-Ion cell on my Schulze, I get a under voltage warning, and the charge will not start. If I try to charge a NiMh cell using the Li-Ion setting, the alarm sounds and the charger shuts down. However, I have to select the right number of cells while I am setting up the charge. Chargers that automatically select the number of cells that you are charging have to be closely watched to make sure they get it right.

Tom

 

[AndyTiedye]

Re: A Cautionary Tale

That does suggest that this "Universal Smart Charger" makes no attempt to avoid
charging an over-discharged battery or battery pack. Li Ions can explode if they
are charged after being run down too far.

If this charger had such protection, and you put in a single Lion cell on the 8.4v setting
it would refuse to charge it, because if it really WAS a 2-cell pack, it should never
have been discharged to a total voltage of 3 or 4 volts, and a properly-designed
charger should detect that.

I think this charger has earned a big fat JEER.

 

[David_Campen]

Re: A Cautionary Tale

The connection is made because you hook the + lead to the + of the battery(s) and the - lead to the - of the batterie(s). Unlike your Christmas tree light example, when the battery is hooked up it completes the circuit.

So you are saying that there is not an individual slot for each battery but a single, long slot that somehow adapts to many different lengths of batteries? Is it spring loaded? It must be a very long spring! I would like to see a photo of this mechanism.

But then you say that "you hook the + lead to the + of the battery(s) and the - lead to the - of the batterie(s). ". This is a description of a parallel connection.

 

[cy]

Re: A Cautionary Tale

norm, is there anyway you could post a better picture identifying charger?

do you have the link of where you purchased charger and cell?

what brand is the 14500 cell? bare or protected?

I understand Silver's explanation of why it happened, but don't understand why this design was allowed to be sold. did instructions specifically warn this would happen. if you selected wrong settings?

some type of safety should have been built-in to prevent user error. if charger was designed to charge li-ion. it's not if this is going to happen? it's more like when...

my triton will not allow this to happen, regardless of user settings.
this goes for any other charger I've used.

awhile back there was a Chinese two cell li-ion charger that would catch on fire. would not damage cell, but charger would be destroyed.

 

[Barton]

Re: A Cautionary Tale

Is the toxic danger in a lithium ion cell the same as a primary CR123A? Do they have similar chemistries? Do they vent the same poisons when they burn?

HF is bad stuff. I read the other threads about the primaries, is the HF danger the same with the rechargeable?

 

[cdosrun]

Re: A Cautionary Tale

The charger has no slot, it simply has two wires coming out to connect to the cells. It is designed to charge packs (whther they have one or more cells) and are therefore connected by a lead. I presume the OP had a couple of leads with magnets on them to connect the cell up to the charger.

I believe the term 'smart' is used with the charger to indicate the it has end of charge termination, over current (short circuit) protection etc. I think it is an easy mistake to make and serves to highlight the care required in handling unprotected Li-ion cells. With this sort of setup, it would also be very easy to connect the cell in reverse (although I believe the charger in use here has reverse-polarity protection). As with the other posters, I am glad that only equipment was damaged (no people).

Andrew

 

[cy]

Re: A Cautionary Tale

title needs to changed to reflect exact charger responsible for this failure. other owners and seller of this exact charger needs to be warned.

you would think that PTC device inside cell would have reacted to high temps and shut down current going in. unless high temps needed to activate PTC was reached after thermal runaway had already occurred.