Hello,

I just taught this would be of interest to all Lithium battery users in RC parkflyers. - Where they tend to be most abused

Not sure exactly what type of battery (Li-Ion, Li-Po or anyother)

http://story.news.yahoo.com/news?tmp...tch_handset_dc

Watch out those cell phones !!!.

"In all cases it was caused by a replacement battery which was not a Nokia accessory. The manufacturers violated security requirements which should prevent it from heating up after short circuiting, for instance, after it was dropped."

Absolutely right, in this case was totally because of user's neglicence.

My point was just to show how explosive these things could be and to not forget to be carefull with batts in general.

Accidents happen to even when you know what you are doing,
at least it happened to me once that even with carefully soldering I produced a short-cut in one of my packs. Needlees to say how hot it got after !

This of course won't take me away from soldering my own packs or installing Lithium packs on my planes

SO

It just goes to show that things can even go wrong in "safe" applications of Lithium Polymer batteries.

Well, she's lucky that it wasn't worse. Elemental lithium is even illegal without licensing, due to the highly explosive nature of lithium (it burns white hot; enough to melt steel without any form of artificial flame enlargener other than the lithium itself.

--Alex

Originally posted by sontiveros
Absolutely right, in this case was totally because of user's neglicence.
SO

I went back and re-read that story, and I still cannot find the "user neglience".

Brad

Originally posted by Andy W
"In all cases it was caused by a replacement battery which was not a Nokia accessory."

Those corporate spin doctors are true artists, aren't they? They managed to pull off a complete publicity polarity reversal.

It's interesting because it's similar to the incident of a crash-damaged LiPo pack starting a fire in the backseat of a car. The way I read it, the lady bought a "no-name" replacement battery pack for her cell phone, and the pack didn't have a proper safety circuit to stop it from self-destructing after it was damaged in the drop. It's a stretch to call this negligence. It sounds more like a "buyer beware" to me. The replacement pack was probably labeled as a "direct replacement" for her Nokia cell phone. Sounds like something that could happen to any one of us. It is a great commercial for "official Nokia accessories."

Dave,

The safety circuit in a consumer Li rechargeable pack can't (and doesn't pretend to) protect against mechanical damage.
The protection circuit is for electrical abuse at its terminals, anything that happens the other side of the circuit like a crunched cell, it can do nothing about.

It is up to the cell manufacturers to produce cells that can withstand mechanical abuse without going critical and this is where the mainstream manufacturers have a lead on the also-rans.

Andy.

The news article was, obviously, not detailed enough for thorough understanding of what went wrong. If dropping the phone caused damage to the cell, and if a safety circuit does not help in this situation, then one might naturally assume that the same thing could have happened with any lithium cell, Nokia accessory or not. So, in the end, this is just another story that shows that things can go wrong, but really doesn't teach us a lot.

though I would give a word of warning about my experience with a Li-ion battery pack and the Triton charger.
It is very easy to set the charge voltage incorrectly!!
I had a 3s2p Li-ion batt that I wanted to charge at 11.1v on the Triton.
You press the dial to set the voltage ,let go, then turn the dial to set the voltage, then press down again. then you press down and hold the dial for 2 seconds and the charge starts, there is no indicator on the main charging data screen at what voltage you set the voltage to, and there is a tendency to hold the dial down,move to the voltage you want,then continue to hold the dial down to start the charge,
IT IS EXREMELY EASY TO ACCIDENTLY MOVE THE DIAL ENOUGH TO END UP WITH A HIGHER VOLTAGE(it take just 1 click, )
I charged this battery for 35 min. and it showed 600mah and the battery was cold.
I left the room for about 10 mins. and the
battery EXPLODED!!!! melting my counter top,
and sending molten metal on top of a samsonite brief case, melting it and catching a
place mat on fire-
Insurance said they will replace everything, including a foam plane 2 ft away that looked liked swiss cheese.
Turned out that I that I had let the dial slip over the to 14.4 setting.
Totally accidental-but still my mistake .
Funny thing is, I have the optional thermo sensor,but I was't using is because IT WOULD NOT FIT ON THE BATT.(EVEN A 2S SIZE).
I WROTE GREAT PLAINS AND THEY JUST BLEW IT OFF!(I guess because I blew it up
I tried later to heat the probe with a lighter
and the meter read -47 F degrees, then with the probe warmer than could be held-the temp climbed to -25 F, then started back down.
so I'm not sure if holding it on with masking tape would even work
Just a word of warning- from someone who learned the hard way.

Keary

Keary, thanks for your excellent description of your unfortunate accident. It's fortunate that a major fire wasn't started. Many of us have been trying to develop safe charging setups that would contain an exploding pack in the event that something went wrong during charging. Yours is one of several documented cases now of packs exploding in a shower of sparks.

It would be helpful to the rest of us if you could estimate approximately how many feet away from your pack the furthest burning ember landed? Also, based on your experience, do you think that charging the cells inside a metal box would have contained the burning embers and prevented anything nearby from being damaged? I've started in the last week charging my lithium cells inside a double wall steel box with fire-retardant insulation between the two steel walls, and I'm hoping this would contain any shower of sparks in the event of a pack exploding.

Just some random thoughts from this thread:

More and more I am becomming convinced that a dedicated LiPo charger that requires the user to manually set and confirm voltage and current is what I will only use.

Of course I want high cell count and at least 8 amps.......

Another thought:

Many of the fires/explosions have been "user error" and it is great that modelers have been willing to share their pain. But what will it be like when we start seeing LiPo in lower end beginner/newbie parkflyers?

Geeze, a kid on the schoolbus taking his plane to show and tell??

I feel like there is a sword hanging over our heads as RC modelers. That sword is labeled LiPo, when will it drop and kill somebody?

Brad

the battery was sitting on top of the metal cabinet of my 10 amp power supply.
the plane that melted was about 3 to 4 ft away on the right side and the brief case was 2 ft away and 2 ft above the power unit.
The main "chunk" landed on the counter as you saw, but my guess the plug to the charger prevented it from traveling further.
I might add that the piece that burned the counter was only the empty shell of 2 of the
cells( I heard 2 dull thuds), and when I saw it, was glowing red hot,
I was incredibly lucky that I had some forceps
handy to pick it up.
My guess is the 1st cell exploded, sending the
6 cell pack to the limits of the attached cord, and the contents landed on the brief case,melting it and dripping on to a cloth matt which caught fire, and the 2nd cell exploded 10 secs later sending the shrapnel
to the plane-my plastic tool box( fist size hole
in it-melting a soldering gun and other electronic parts) and landing on the back
of my radio melting a hole thru it.
-- My biggest concern is that while the Triton is a very good charger- 2 little design changes(making confirmation of charging voltage and not being able to start the charge by continuing to hold down the dial(which by the way tends to stick) and the design of the OPTIONAL temp probe which prevents it from being used on square Lithium batt.would have prevented my error.
Also the manufacturers lack of concern about the design of the temp probe is disturbing.
If the probe would have fit the cell pack , I would have used it.
I just hope that if Li-Po spread to the"kiddie"
market- that there be design changes to prevent both internal shorts( as I have read on other similar posts) and in dedicated chargers with fixed outputs and self contain temperature
moniters.
Dave, I think that would be a very good idea
about the box, I am getting one of the smaller fire-resistant boxes from wally world- removing the lock to thread the wires thru, and using an outside clip to hold the top down to charge all my batteries ,I have also set all my timers for 30 minutes and will not charge above 1 amp. on the lithium batteries
keary

Good stuff, keary. Thanks for the detailed explanation.

Brad, I'm with you on the dedicated LiPo charger. I just missed the cut on getting my SC2 order filled, and will now be getting one of Troy's second generation dedicated LiPo chargers. I suspect that reading some of these threads will influence how Troy designs the second generation SC2, although I don't recall anyone reporting any safety problems with the original SC2.