rw Guinn

Ok,
"splain this one to me.
Bought a new. 2 cell 700 mah lithium Polymer battery pack yesterday. Along with a new charger.
the Battery was checked out on the A/C system, and then put on the charger. Charger is FMA Direct LIPO-203. 220ma charge, till the charger quit charging (light went out), about 3 1/2 hours.
Took them off the charger, set them on the counter. 2 hours later, we stuck them in the airplane-a "littlest Stick", and put the wing on. Barreries are just in the airplane, not connected to anything. Just setting there.
15 minutes later, smoke is pouring out of the fuselage. Batteries are STILL not connected to anything, except that all the insulation is melted off of everything in the fuselage, and batteries are swolen up like to Nicad size. Big mess. May have gotten so hot as to melt the reciever, which was in the same general area.
Any ideas? If these things are THAT dangerous, maybe we need a different power supply.

Roger

RC Extreme power

My Feedback: (24)

Could have been a short inside the pack. I would get in touch with the vender that sold them and see if they have had any other problems with the brand that you got. I dont know the charger that you have but do you have to change jumper for different cell count.
Milton

RedBarronBen

That sucks! I have been using Kokam brand lipo's for a few months now and I find that they are working excellent for me. I use a 1500 mAh, 3cell (11.1V) pack in my "super-spree" with a brushless setup and the power vs. weight is incredible. Anyhow, I find that charging my 1500 mAh batts at 1C (what is recommended by the manufacturer) (1C in this case is 1.5 Amps) it takes about 70 to 80 minutes to get a full charge after running the battery down to about 9.0V (min. discharge recommended). If your batts are charging for 3 1/2 hours, I think something is wrong with your charger or its setup. Something else: when I charge my lipo's, they do not heat up at all, they stay room temp. If yours got hot whilst charging, something was probably out of whack.
When I discharge them in the airplane though, they get hot. Hot is a relative term I know, but I think around 110 - 120 deg. F might be close. They feel hot, but not so much that you can't handle them. This is in FL too, where the temp. is about 90 to 95 deg. lately.
Hope some of this helps. Anybody else experience different?
This is high-tech/new-tech stuff to be sure, and needs to be handled with respect. Learn all you can about charging and discharging these batteries, find out what the battery manufacturer suggests. Understand the terminology and what it means for your particular battery.
Also, check your esc set-up - it will be different for a lipo than a nihm or ni-cad. This is important to your radio reception at the end of the flight!
My opinion is that these batteries perform much better for model aircraft than the nihms or ni-cads. Energy stored vs. the weight is better than any other electric set-up I've tried.
Good luck!

rw Guinn

The charger I bought will only charge at a max 220ma rate, which for a 700mah pack is 3 to 3-1/2 hours.
What is scary is that it was a good 2 hours after they were disconnected from the charger, and it was just sitting there, unconnected with anything when it blooied!
Made a mellofahess inside the airplane.. I have e-mailed FMA asking whether it was bad technique, bad luck, bad cells, or bad Karma (The smoke all came out when I entered the room)

and more info on the ESC set-up? What do you mean it needs to be different?

Roger

edited to add question on esc

Matt Kirsch

My Feedback: (21)

I believe the "special ESC set-up" he's referring to is programming the low-voltage cutoff (LVC) so it shuts the motor down when the pack reaches 3.0 Volts per series cell. Strictly optional, IMHO. Technically, the ESC will work just fine if you don't change any settings, but if you insist on flying the plane until it won't stay in the air anymore, you can draw the LiPoly cells down too far, and damage them.

You should be using a timer regardless of whether you have a programmable LVC or not. Figure out how long you can fly by making short flights, then measuring the voltage. Add 'em up, knock off a couple minutes for landing, set the timer, and recharge.

Greg Covey

The most likely scenario here is that the Lithium pack was overcharged.

When a Lithium cell or pack is overcharged, the degree of overcharging determines the delay before combustion. Typically, you will get some degree of bloating long before the combustion occurs.

If you see a pack bloat when charging, the best approach is to take it outside on a concrete surface and poke holes into the pack with razor knife, ice pick, etc. If you don't release the Lithium, a fire will result soon enough.

Assuming that the cell count was correct when charging, a faulty cell can make the pack look like it has one less cell which results in overcharging. The newer chargers like the Apache 2500 or Astro Flight Lithium 109 have much more safety procedures built into them as well as automatic shut-off timers for 60 minutes max.

Matt Kirsch

My Feedback: (21)

Greg, I've read accounts where poking a bloated LiPoly caused it to catch fire.

Probably the best course of action with a bloated LiPoly is to take it somewhere safe, and wait it out. While you're waiting, prepare a bucket of salt water. If the pack hasn't gone up yet, scoop it up and put it in the bucket, letting it soak until it stops bubbling.

rw Guinn

That is all well and good, but>
The cells never even got hot while charging (I checked Frequently)
they appeared just as they had before charging
they waited over 2 hours to blow up. Thats over 2 hours without being connected to anything at all.
These things are outrageously dangerous!

Roger

Ultimate3D

one thing that i would keep a check on is how fast are you chargeing them. ex. and 1600 mah battery should at most be charged at 1.6 amps and i don't charge mine that fast

rw Guinn

I give up!
I say :" 220ma charge, till the charger quit charging (light went out), about 3 1/2 hours. " on a 700mAh battery. I get "keep a check on is how fast are you chargeing them. ex. and 1600 mah battery should at most be charged at 1.6 amps and i don't charge mine that fast"
I state "220ma charge, till the charger quit charging (light went out), about 3 1/2 hours. " on a 700mAh battery.
I get:
"The most likely scenario here is that the Lithium pack was overcharged. "

I charged these things at 220mA. Measured. I asked for help. I stated the circumstances. I get accusations.
Electric, and LiPo's especially, are extremely dangerous, obviously.
I will therefore work to get them banned from use, anywhere. Its the only solution, since nobody who uses them has the foggiest notion of what makes them go boom![:-]

Ultimate3D

sir what makes them go "boom" most of the time is heat. heat can be caused by many things such as overcharging and dischargeing them to fast!! another thing that will cause it blowing up is if you drop them and it cracks the pack. so i do know what make them in your words "GO BOOM"

Ultimate3D

we build li-poly batteries and we do a ton of testing to see what will make them blow up!!
so i know what you can and CAN'T do

rw Guinn

So, If I charged them at 1/3 C, on a brand new battery pack, per the manufacturers directions, fresh out of the wrapper, they did not get hot, they did not noticably swell up, and they charged for a little over 3 hours...
what made them go "Boom" 2 hours and 15 minutes after they were taken off charge, in an air conditioned room?

Ultimate3D

most likely there was a short in the battery and it got so hot that it started to smoke and melted the insulation. What type of battery was it kokam thunderpower what?

rw Guinn

Kokam

Heck of an intro to Li-Poly. lose the battery, and the heat destroyed all servo leads, and the reciever., nott to mention the black char stuff inside the airframe....

Ultimate3D

that happens tell kokam about it and should give you another one how much was the battery?

majesticmonkey

My Kokam Packs came about 1/2 charged from the manufacturer. Maybe this is you cause of overcharging.

Marcus

ChuckAuger

My Feedback: (12)

Not accusing, but were you sure you had the charger set to 2 Cell, or 7.4 V or whatever, and not 3 Cell, or 11.1V?? What Charger was it??

OK I missed it..FMA charger...

PaulVi

I hate to ask. Was that pack droped at any time before or after charging. Internal damage or a faulty pack from the vendor (Who could have droped it befor packing it) could be the root cause. But. I still state that and I know I am asking for my own GO BOOM Pack now.. I have not had any problems in the year that I have been using my packs 1200mh 2 cell charged at 800mh untill the charge lite goes out. This is a 8.4 volt charger used to camares it has been midified to use the JR type conectors..

I am sorry for your lose but please do not catagorise every lipo as being bad or unsafe. Many of the horror storys we read about come back to home brew chargers and or forgetfullness.

In your case this seems not to be the cause but rather a default on the packs part.

Good rule of thumb is to always cycle your packs in a test condition before palcing it near your expesive stuff. I do the wan for Nicads as well. I still have a hole in my cealing where a core from a NiMh blew out (My Fault I was testing to see how hard I could push it.)

Sabot

Everyone already said they thaught you had a faulty pack - and were discussing how overcharging makes them 'go boom'

Ok consider this then: no one else said their pack has blown up unless it was faulty, my cell phone has a li-ion battery in it and it hasnt 'gone boom' yet after a year,

And its very clear from the thread that dropping them or overcharging them makes them blow up so how can you say:

"I charged these things at 220mA. Measured. I asked for help. I stated the circumstances. I get accusations.
Electric, and LiPo's especially, are extremely dangerous, obviously.
I will therefore work to get them banned from use, anywhere. Its the only solution, since nobody who uses them has the foggiest notion of what makes them go boom!"

one pack 'went boom' and you think the entire world should distroy their li-ion batterys i dont think so.

rw Guinn

Obviously, no sense of humor there. Can't read either.
I even went against my normal policy and inserted a at the end, indicating the sarcastic nature of my tirade....

PaulVi

remember opinions are like A**H**** everone hasone and they usally stink.. [X(]

Johanto

Hi all,

I'm a Kokam distributor tucked far,far away on the Southern Most point of Africa, living in a placed called Cape Town. For anybody wondering where Cape Town is, right at the bottom of Africa. www.BallisticRC.co.za

I personally have a few Kokam packs that I use on indoor and outdoor configurations. Ranging from an Ikarus Shockflyer to a .40 size Kyosho Cessna electric converted. A MScomposit Hornet etc.

I'm using a Great Planes Triton Charger and I have a JJ Power Kokam charger specifically sent from the Kokam manufacturer.

Till date no booms but I do had 2 packs that went bloaty on me.... 1200mah 7.4C rated max 4C. Why? Well I misused and tested them on a Shock Flyer with a AXI 2208/34 and a 8 A Jeti Advance ESC out of the 4 packs tested I only got 2 off them bloaty due to putting allot of Amps through them with prop hanging etc.

I've dropped packs quite hard from out my Shock Flyer due to doing crazy stuff 2 to 3 feet off the deck. No boom yet. [:@]

I keep to the following rules:
1. If a pack size is let say 1500mah 7.4V I will charge it on the Triton at 1.5A on 7.4V etc.
2. Do use a Digital charger either the Triton or the Kokam JJ power unit. When in doubt you can always monitor the on screen display telling you what's cooking. I use a stepdown transformer giving me a constant 13.1V output for my chargers. Do invest in one of these.
Personally I do not like connecting it to a 12V battery. And it takes forever.......[:'(]
3. When attaching the pack to my shock flyer or what ever I use some masking tape to keep it in it's position and also preventing it from becoming a projectile while doing a snap role. The foam inserts does'nt keep it there. And if you do hit the deck, mostly the pack does'nt impact with the floor or whatever. It only pulls loose and dangle's around.

Till date no boom and no smokers yet...... Maybe I'm just lucky????

If you do damage a pack dropping it from afar in the blue yonder and it does seem damage. First discharge it completely.... cause??? If you stick a ice-pick (metal) like mentioned above somewhere through a charged pack it will go boom in your face. It's a DEAD short. Rather use a wooden skewer after its discharged. Then dump it in the salt water.

I've never used a voltage protector unit like on FMA's site, never charged it in a pyrex bowl ( I presume this is made off glass??? Hey if it goes boom you'll have glass shrapnel everywhere.. just a point to ponder???) The best method is take a metal pipe 3 or 4 inches in diameter by at least 3 feet. Charge your pack inside this (Around the half way mark), if it does ignite or go boom the metal pipe will absorb most of it and whatever's around won't go up in flames or you don't have to take glass out off your 1/4 Scale pilot's face...[X(]. Hey and at least you don't have to go sit down in your dungeon hole with stone walls and a 10 feet charge fly leed. Cause just maybe,maybe it goes boom!!!!!


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