E-Flight Power Sources Ask questions or read about power sources as they specifically relate to e-flight including Lithium-ion, Li-Poly, Nimh and Nicad battery packs.

LiPo FIRE

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Old 08-13-2003, 10:50 AM
  #1
hoppyfl
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Default LiPo FIRE

Saw this on another forum. http://www.rcgroups.com/forums/showt...79#post1206279

To add my story, I also had lipo's catch fire. I will admit that my charger (one that is supposed to correctly charge lipo's) incorrectly put in more amps and created a problem, but the results of this were not nice.
I was working at my bench and charging batteries (my first LiPo pack) when I heard a crinkeling sound. Saw that my LiPo pack was swelling up so I quickly disconnected it. I expected that it would cool down being disconnected, on it's own and left it be. As the swelling seemed to be abating I figured I was only out a new battery but that was all.
Wrong! 10 minutes later the pack exploded showering sparks in a 20 foot circle. I ran for my fire extinguisher and was about to let it go when the other side of the pack blew also. (2 cells -1300mah) More sparks and finally much powder all over the place and my planes, bench etc.
I admit I am at fault here, but advise the following:
These batteries must never be charged without supervision even though they take a long time. If I had not been there I may have lost my house! (Never mind the irate spouse)
These batteries cannot be trusted after any unusual event, such as hard landings etc. We will continue to use them in our hobby, for sure, as the power of advertisements and marketing will go on. However, I thing there is a level of negligence on the part of manufacturers and vendors, in that needed warnings and advice are, in my opinion, seriously lacking.
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Old 09-01-2003, 11:39 AM
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Greg Covey
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Default LiPo FIRE

Good advice, Hoppy.

I hope all is well.

The key to Lithium safety is in future charging advancements. I am curious to see what develops before too many folks start using them.
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Old 09-03-2003, 09:58 PM
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Default Li-Poly

I have 2 kokam 11.1 volt 1200 and have
had no problems. I use the Kokam 402
charger that only charges lithium.
I get over 20 minute flights using a
speed 400 I really enjoy the long flights.
I think one problem is people using
their ni-cad chargers.
Frog
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Old 09-04-2003, 11:11 AM
  #4
Matt Kirsch
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Default LiPo FIRE

Actually, Frog, most of the fire people swear up and down they're using an "approved" charger for LiPolys.

The biggest problem is that people are doing stupid things like putting a crashed LiPoly-powered plane in their car right after they crashed it, then leaving it unattended while the go crash another plane. No self-respecting glow plane pilot EVER puts a crashed plane back in the car without first removing all the fuel. Why should it be any different for an electric flier?

Another classic cause of LiPoly fires is unattended charging. People put them on charge, then go out for groceries, retire to the far end of the house to sleep, or otherwise leave the cells charging completely unattended. I'm not saying you need to stand poised over the cells with a fire extinguisher, but be in the vicinity, and check them from time to time. There is one recent account where a person was nearby when a cell failed on charge, and because he was paying attention, put out the burning embers of the cell before they caused a serious fire.

You read these threads, and lots of, IMHO, OUTLANDISH methods of handling these cells come about. People talk about lugging around fireproof safes. They recommend charging with the batteries suspended over a bucket of salt water in a plastic bowl so that if the battery gets hot, it melts through the bowl and drops into the salt water where it's neutralized. I've read accounts where people charge in a steel barrel on a concrete pad in the middle of their yard. What's next, a Brinks armored truck to transport them to the field?

Frankly, I think some plain old common sense will prevent 99.9% of the problems without having to resort to extreme measures. Spot check the charge process with a voltmeter from time to time. You don't need to charge on fire brick, but don't charge them where there is a lot of highly-combustible material around. Your run of the mill table requires the application of a significant amount of flame for a significant amount of time before it will burn. Ever tried to set a table on fire with a Bic lighter? It's a good idea to have a smoke detector and fire extinguisher around, but you should have those around the house and shop anyway.
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Old 09-04-2003, 01:19 PM
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Default LiPo FIRE

While I agree that the users need to be better at keeping a eye on the charging process the problem is that people get distracted and forget about what they should be doing. Result is that you have accident when you least expect it.

IMHO the makers of lithium batteries and chargers have to make them at least as fool proof as Nicad and NiMH chargers are now.

Steve
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Old 09-04-2003, 02:16 PM
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Default LiPo FIRE

Hello Frog

Can you tell us more about your setup? Are you using your 2 packs of 11.1 volts in parallel when you use them with your speed 400? What kind of plane are you using? Do you know how many amps the speed 400 is using? I would like to get 20 minutes of flying with my speed 400 too.

Do you check the voltages of each cell before you charge your packs?

Thanks
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Old 09-04-2003, 05:05 PM
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Default LiPo FIRE

Hi Cork
I use 2- 3cell packs 1200mah in paralell
it gives me 2400mah and 11.1 volts I have flown a Wingo a Sunny Boy and a
Pico cub all on floats some with gear boxes. I sit on my dock and use a kitchen
timer. Flying 20 + min. is much better than 6 min. on ni-cads. I think over charging from using the wrong charger
is one problem that people have.
spend the bucks Tower Hobbies has the
Kokam 402 charger for $83.
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Old 09-05-2003, 12:16 PM
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Default LiPo FIRE

Quote:
Originally posted by Matt Kirsch
Actually, Frog, most of the fire people swear up and down they're using an "approved" charger for LiPolys.

The biggest problem is that people are doing stupid things like putting a crashed LiPoly-powered plane in their car right after they crashed it, then leaving it unattended while the go crash another plane. No self-respecting glow plane pilot EVER puts a crashed plane back in the car without first removing all the fuel. Why should it be any different for an electric flier?

I can see how it would be prudent to remove the fuel from a crashed airplane.

Tell me what to do with an electric plane. What should I look for and what should I do if I see it? How do I know if or when the battery is "safe"? How long should I wait? What are the signs of a damaged ready to explode battery. If I remove the battery, what should I do with it? Can a visibly undamaged battery catch fire? So many questions.......
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Old 09-08-2003, 06:58 AM
  #9
Matt Kirsch
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Default RE: LiPo FIRE

First, if you crash, remove the cells from the plane. Second, don't put them in your car until you're ready to leave. Even if you're going home, don't throw the cells in the trunk where you can't watch them.

Planning on sticking around the field for a while? Put the cells out in the open where, if they go critical, they won't cause serious damage to people or property.

One of the manufacturers has recommended a ten-minute waiting period after a serious crash, just to be sure that you won't have problems. The longer it goes, the less likely it is you'll have a problem.
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Old 09-09-2003, 02:15 PM
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Default RE: LiPo FIRE

All Lithium-ion Cylindrical cells have gas release vents, a current interrupt device, and a PTC device inside of the cell. Each of these systems are installed to provide some protection if the cell is pushed outside of it’s basic operational parameters, the cell is trying to protect its self from failure. Because lithium is a reactive element, safety concern is very important. Overcharge (voltage) of a cell will aggregate lithium metal on the anode and lead to thermal runaway. The systems like the gas release vent can’t support a mayor over voltage experience during charging, the result is less than desirable.

The “Lithium Polymer battery” used in the hobby and in most commercial applications is really a Lithium-ion battery that has had the internal power generating materials folded to be a flat matrix instead of rolled up to fit in the cylindrical can, it is then installed in a light aluminum container that was original designed for food storage but it works fine. There are only 2 companies in the world at this time that produce a true Lithium Polymer battery. The good news is that the “lithium Polymer battery” is a bit lighter and has the ability to support higher loads because of the better heat distribution and the ability to dissipate that heat under higher loads. This is the good part; the other side of the coin is that under the charging process the “Lithium Polymer cells” don’t include any of the safety systems that are part of a Lithium-ion cylindrical cell, so the cell has no way of protecting itself. This then requires control of the charging cycle imperative. There was/is a false presentation in the hobby that the “Lithium Polymer Battery” is completely safe and won’t create an unhappy experience. The electrolyte used in these cells is liquid and flammable. If the cell or pack is overcharge (voltage) for any reason the first indication is that the cell will start to blow up like a balloon. If you are lucky the cell pops (gas release vent) and you cut off the charge before further problems. I will say that lithium doesn’t like exposure to oxygen so don't think the experence is over, remove the pack to a safe place incase of a thermal runway.

The point is that we must take every step to create a safe and reliable product for the end user. Taking a chance that something won’t go wrong is a bad philosophy when we have the ability to provide safe charging circuitry in the pack when it is built. In my racing days, 35 years, we looked at every situation with 3 basic criteria. First and foremost was safety, hurting or killing your driver was not an option. Second was performance enhancement, you want to outperform the other guy. Last was the cost, this was mostly a concern of the Team owner.

I hope this gives you an over view of the system we are using, each of us must read instruction and educate ourselves. The lithium-based products are the future like Nicads were 50 years ago and they are here to stay.

I have included an overview of the Duralite Plus teams attitude regarding the use of Lithium-ion and Lithium Polymer batteries below.

Thanks for your question,

Emory


DURALITE BATTERY TEAMS OVERVIEW

Our team understands the importance of having products that are safe and reliable. We have spent considerable time and resources researching and developing the best, most reliable battery system available today.

The charging process is the most critical in regards to safety. We feel very strongly about the “Charge Safe Circuitry” installed in our pack. The “Charge Safe Circuitry” is installed in the pack to monitor each cell’s voltage and the total pack voltage during the charging cycle. This allows each pack to be charged to the proper voltage providing safe charging, maximum pack performance, and long life. It should be noted that we install the safety circuit in our packs because the Lithium-ion and Lithium Polymer battery cell manufactures we work with indicated the circuitry must be part of the pack. Several companies we work with require that you sign an agreement to that effect. Only suppliers of packs to the hobby segment have decided this protection is not necessary, this is a bad philosophy. Ask the question, why would all of the major suppliers of Lithium-ion and Lithium Polymer batteries Sanyo, Panasonic, Saft, and etc. refuse to sell a pack without this protection. The safeties are there to protect the end user during the charge cycle. There is always the potential that an inappropriate charger, malfunctioning charger, or an incorrectly programmed charger being connected to a Lithium-ion or Lithium Polymer pack. As you can image there is a substantial cost for quality circuitry, extra pigtail and other required parts to make a safe pack.

The “Charge Safe Circuitry” controls the charge cycle of the battery pack and is designed to monitor the balance between cells in the pack and the total pack voltage. If any cell reaches the 4.35 voltage threshold or the total pack voltage reaches 8.6 volts then the charging process stops. At this time DURALITE PLUS is the only hobby battery supplier that includes this safety circuitry in each pack and will not supply single cells or packs without the safety protection. Don’t charge any Lithium-ion or Lithium Polymer pack without in pack safety protection.

DURALITE PLUS battery packs are supplied with two leads. The Yellow colored connector lead is for charging. Charging current passes through our “Charge Safe Circuitry” allowing for a fast and safe charging process. The black power lead is connected directly to the battery pack cells allowing for uninterrupted power to the receiver and servos; it does not pass through the charge circuitry. This is the same power connection to the cells/pack utilized by all Nicad and NiMH pack builders. This black connector plugs into the switch harness as usual.

The Duralite Plus Battery charger is a smart charger that uses an internal controller that evaluates the pack’s charge condition and properly ends the charge at the appropriate voltage. Also, many companies are now supplying chargers that will support most battery technologies including the Lithium-ion or Lithium Polymer. You MUST READ THEIR INSTRUCTIONS for these chargers. Be careful when setting the charging parameters, as the Lithium based rechargeable batteries are not tolerant to overcharge voltage.
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Old 09-09-2003, 07:33 PM
  #11
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Default RE: LiPo FIRE

Hello Emory

I'm a bit confused about your statement that there are only two manufacturers making true lithium polymer batteries.

Does that mean that the various lithium polymer cells that we have available for R/C such as the Kokams, Etecs, Thunder Power, HEcell, and the new one by CBP are all made by just the two manufacturers, or does it mean that they are not true lithium polymers?

I've also seen lithium polymers from Sony and I think from Panasonic.

thanks
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Old 09-09-2003, 09:16 PM
  #12
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Default RE: LiPo FIRE

Cork,

Yes, the batteries we are using in the RC Hobby are Lithium-ion Batteries in an aluminum container. They have a liquid electrolyte. If you dissembled one (probably not a good idea) you will see that it is a folded Lithium-ion battery. Nothing wrong with this as it does dissipate the heat well and works fine for our application as long as we handle them correctly. I have been told that there is a Hobby store supplying Ultralife batteries to the Hobby and they do manufacture a true Lithium Polymer battery. Ultralife’s main customer is the Military but they indicated to me that they weren’t at all excited to have their batteries used in our environment.

I guess that the main though I wanted to communicate was that the Lithium-ion and Lithium Polymer batteries are working great in the hobby and they will be around for a long time to come. As modelers we must understand that we are using a very high-density energy product and it must be handled with care. If there is a safer way to present the product to the end user then it should be taken into consideration.

Have a good day,


Emory
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Old 09-09-2003, 10:06 PM
  #13
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Default RE: LiPo FIRE

That's hard to believe that all the companies making lithium cells for R/C are calling them lithium polymer cells when they are not really lithium polymers.

Maybe we need a better definition of what a lithium polymer cell really is.

Care to give it shot, Emory?
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Old 09-10-2003, 06:13 PM
  #14
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Default RE: LiPo FIRE

[link=http://www.powerpulse.net/powerpulse/archive/aa_080601a1.stm]Here[/link] is an interesting bit of info.

Bill
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Old 09-10-2003, 09:20 PM
  #15
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Default RE: LiPo FIRE

Looks like Bill's Post gives the information regarding the difference between the batteries we use in the hobby and a true Lithium Polymer battery. Again its great to see the interest in learning more about this technology we are using for powering our vehicles. Everyone have a great weekend and stay safe.

Emory
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Old 09-12-2003, 06:40 AM
  #16
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Default RE: LiPo FIRE

Quote:
...people are doing stupid things like putting a crashed LiPoly-powered plane in their car right after they crashed it...
- Matt Kirsch, Administarator

I object to characterizing a mistake as "stupid", particularly by an administrator.

LiPolys have only been available for eflight for about a year now. We are still learning.

If Kirsch's snotty way of expressing himself were the norm. nobody would be willing to post his misfortunes, and we would all be the worse for it.

- RD Blakeslee
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Old 09-12-2003, 08:00 AM
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Default RE: LiPo FIRE

Quote:
ORIGINAL: RD Blakeslee
I object to characterizing a mistake as "stupid", particularly by an administrator.

LiPolys have only been available for eflight for about a year now. We are still learning.

If Kirsch's snotty way of expressing himself were the norm. nobody would be willing to post his misfortunes, and we would all be the worse for it.
Your the first, and only person to take offense because you're the first and only person to misinterpret what I said. I said the mistake was stupid. That's what the phrase "stupid things" means. I never said the person was stupid. If I was calling the person stupid, I would've said "stupid person."

Smart people do stupid things all the time. Don't you think the person who made the mistake would also characterize what he/she did as "stupid?" I think you're a smart and all-around okay guy, but your objection to the use of a stupid word is, well, stupid. Please note that I said your OBJECTION was stupid, but that you were smart

BTW, I am not an adminstrator, just a moderator. System problems, you know...
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Old 09-13-2003, 07:01 AM
  #18
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Default RE: LiPo FIRE

"Stupid is as stupid does" - Forrest Gump

Why not drop the rationalizations, and the word stupid, from your commentary, Mr. Kirsch?

- RD
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Old 09-15-2003, 08:30 AM
  #19
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Default RE: LiPo FIRE

'Fraid I can't do that, Mr. Blakeslee... That would be, well, stuipd, for lack of a better word.

The point needs to be hammered home that we cannot afford to be complacent, irresponsible, and yes, stupid, in our treatment of LiPoly technology as it is now. This is of the utmost importance. As soon as someone is seriously injured, or dies in a fire caused by LiPoly batteries, we lose them. Heck, even if nobody is ever hurt, if the insurance claims for property damage due to LiPoly fires cost enough money, we lose them. First, the AMA will add a no-LiPoly rule to their safety code, which precludes all AMA members from using them. Next, the government will get involved, "logically" concluding that an electric aircraft that bursts into flames given a severe enough impact, and a few minutes to stew, is a terrorist threat.

We MUST be careful with them. No dancing around the issue. No excuses.
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Old 09-16-2003, 08:37 AM
  #20
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Default RE: LiPo FIRE

As a complete Lipo novice (haven't got any and thought I should research carefully before getting some) I want to learn from other peoples stupid mistakes first.

Reading this, perhaps I will give it longer before trying them. Thing is with Jason Shulman showing that electric can now match IC in terms of power to weight, this will only get alot more popular.

Perhaps slightly more worrying is that I have one of these cells in my pocket, attached to my mobile phone.
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Old 09-16-2003, 07:42 PM
  #21
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Default RE: LiPo FIRE

sat I attended neat..I learned alot about these batteries..I saw firsthand the danger that can occur when things go wrong..these batteries sometimes dont give a warning that they about to explode and man the flames are big!!! I think for the time being I will use my nicads and hydidres ..and I am not anti poly ..but unless you have a healthy respect for the potential dangers and want your house when you wake up the next morning you need to heed the warnings and friendly advice being given out..never leave them unattended while charging..I saw the aftermath when they let loose in a guys wagon!! ouch!!
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Old 09-16-2003, 10:22 PM
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Default RE: LiPo FIRE

On page 2 of the information in the link I posted above, I found the following very interesting.

Quote:
A critical issue with the pouch cell is swelling, which occurs when gas is generated during charging or discharging. Battery manufacturers insist that lithium-ion or polymer cells do not generate gas if they are properly formatted, are charged at the correct current and are kept within allotted voltage levels. When designing the protective housing for a pouch cell, some provisions for swelling must be taken into account. To alleviate the swelling issue when using multiple cells, it is best not to stack pouch cells, but lay them flat side-by-side.
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Old 10-07-2003, 11:35 PM
  #23
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Default RE: LiPo FIRE

please see my post for the lipo fire solution.
"kokam solution for lipo fire"
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