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What happens if a lipo 'goes off' inside an ammo box?

Old 10-04-2013, 06:16 AM
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xmech2k
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Default What happens if a lipo 'goes off' inside an ammo box?

Will there actually be a sound? No, actually, I was just wondering how the fire would be. I understand it's the lithium's reaction to the air (oxygen) that makes it flare up once the case is open? So in a small space with limited air, would it be a slow burn? Anyone have a lipo incident inside an ammo box?
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Old 10-04-2013, 06:20 AM
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CHELLIE
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I think pressure could build up and cause a problem, might be a good idea to drill a couple of small 1/16" vent holes in the canister, that would make it safer and still keep any fire inside. pressure vents are a good thing
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Old 10-04-2013, 06:23 AM
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great idea -- will be boring some holes in one of mine and use that instead -- I guess I rolling the dice on mine. pretty much just store them with all my other parts in the tool box. I am thinking 1/8 or larger would be a little more safe as a vent.
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Old 10-04-2013, 07:26 AM
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The ammo boxes I've seen dont have any form of seal, so I dont think pressure build up is a realistic scenario, not something I'd personally be concerned about.
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Old 10-04-2013, 08:55 AM
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Mine have a good seal on them. That may be a good idea to vent it, but I still want to hear from an expert regarding the chemical process if there is a good seal.
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Old 10-04-2013, 09:28 AM
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No-one remember School Chemistry lessons .. experiments with Sodium, Potassium etc. ? How they were stored in oil to avoid moisture contact ? NOTE : MOISTURE .... not Oxygen.

OK ... vents on a box ... keep them SMALL ... as many as you like ... but SMALL .. in fact TINY ... Why ? Flame arrestors on tank openings on ships etc. use fine gauze - that way flames do not pass through ... surprising but true. On your box - you would want similar .. allow the item to burn out - but not ignite surrounding area.

Second .. if the box is sealed and MOISTURE with oxygen depletes ... the Lithium will cease to burn - BUT will be waiting for you to open the box !! In goes the moist oxygen laden air ... up goes the lithium again.

So what to do ? Personally I do not use sealed boxes or anything like .. I would prefer to have a container that can be thrown aside to safe area with items inside burning COMPLETELY out and not waiting for me to open the container and get a flare-up ...

My tuppence worth ... others may disagree ... no problem,.

Nigel
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Old 10-04-2013, 03:49 PM
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My ammo cans have seals on them. I was always told fire needs oxygen, and inferred that as long as it was contained in the box, there would be no fire...of course when you open it...boom. But I don't know.

Most of the battery fires I've heard about have either been rather immediate from damage, or during charging. I wouldn't think potential fire during storage would be too much of an issue....But then again, I don't know. The only problems I've ever experienced with lithium batteries is puffing or poor performance.

I had a pack that was puffed. Took it outside, put a full charge on it. I beat it with a stick, even punctured it, and nothing happened. I finally set it up against my target and shot it with a .22 pistol. It flashed for a millisecond, then just kind of fizzled....it wasn't even violent enough to set the grass it was laying on aflame.

Keep in my mind I don't recommend that.
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Old 10-04-2013, 03:50 PM
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Fire needs oxygen,right? So, eliminate the oxygen. Not sure why you would want to vent the fire. I've been storing mine in an igloo hard plastic cooler. Figured if anything, it would starve the fire from oxygen.Maybe I'm wrong in this.


How does lithium react to water? Anyone ever to try extinguish a burning lipo with water? Just wondering if it's a like a magnesium fire.
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Old 10-04-2013, 03:52 PM
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waytooslow
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Originally Posted by crash_out View Post
My ammo cans have seals on them. I was always told fire needs oxygen, and inferred that as long as it was contained in the box, there would be no fire...of course when you open it...boom. But I don't know.

Most of the battery fires I've heard about have either been rather immediate from damage, or during charging. I wouldn't think potential fire during storage would be too much of an issue....But then again, I don't know. The only problems I've ever experienced with lithium batteries is puffing or poor performance.

I had a pack that was puffed. Took it outside, put a full charge on it. I beat it with a stick, even punctured it, and nothing happened. I finally set it up against my target and shot it with a .22 pistol. It flashed for a millisecond, then just kind of fizzled....it wasn't even violent enough to set the grass it was laying on aflame.

Keep in my mind I don't recommend that.
Hold my beer and watch this.....
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Old 10-04-2013, 04:29 PM
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The 'ium' series as my lab jokingly call them maintain burning without use of external source oxygen.

The fire triangle of Heat, Oxygen, Fuel applies to all fires BUT lets take Magnesium for example ... on ignition the oxygenate is supplied by the item itself and it burns even under water.

I've seen many Mag flares fired of and land in the sea - you can watch the descent of the burning flare as it sinks deeper and deeper in the water.

I am not a chemist myself ... so cannot describe the actual mechanism ... but believe me - moisture is the key ..... with LiPo ... and I am not talking visible amounts ... I am told that Lithium fire will continue to burn even in a sealed environment and depleted oxygen levels.

Nigel
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Old 10-04-2013, 04:52 PM
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Thanks Nigel,

Good to know. Years ago, I actually witnessed a mag fire in a very large machining operation that makes constant speed drives and pumps. Now called UTC Hamilton Sundstrand. On detection, they had an overhead Co2 dump system whereby you had 45 secs to exit the building before the air is too heavy to breathe. So, maybe I need to install a Co2 dump system in my detached garage. Whew ! Have collected quite a few lipos over the last 3 years. I try to keep them at storage voltage but it's hard to go and check the status of all of them.
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Old 10-04-2013, 05:12 PM
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Good info, Nigel. Thanks.

I've poked around a bit and found a thread on RCG where a guy deliberately blew I think a 4s batt in an ammo box with a 3" vent hole. The ammo box still blew open! Starting to sound like they may be a false sense of security, if not an escalation to the problem...

I guess I really started being concerned when i saw an incident at a field I fly at a couple of days ago. I didn't realize he was doing it, but another club member was charging a battery on the folded down back seat of his SUV, off a 12v car battery sitting in there. He was at the fence, I was near my car, about 2 to 3 car widths away from his. We both heard a not too big pop from the vicinity of his car. He asks, 'did you hear something?' I'm like 'yeah, something over by your car'. He quickly goes over to the rear passenger door, I see him looking a brief moment, then I see him doing something quickly, then he tosses a lipo out towards an empty area of the pits. In less then 2 seconds, it goes. Fire shot up and out one side for what appeared to be a 2 foot flamethrower! At first he said he was charging properly, though not balancing, at 1C. Later he realized it was a 4S batt, but he thought it was a 5S...

OK, so I understand that's not a battery just being stored, but things happen, so I'm starting to give a little thought to this. Now I'm wondering if the only real safe thing to do is build a refrigerated concrete bunker in the precise center of the back yard, away from anything flammable!

Ugh, this reminds me, I have to put a storage charge on my batts from that days flying.
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Old 10-04-2013, 05:37 PM
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Yikes ! A Roman candle going off in the back seat. I've seen a couple guys drive big stakes in them. A lot of pressure built up in these things. I agree. Things happen when we get complacent. Steven Wright's law: " If everything seems to be going well, you have obviously overlooked something."
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Old 10-04-2013, 05:38 PM
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Batteries are much less hazardous when part discharged. For 'fun' I knocked a nail through an old 3s 2200 that has about 3.7v per cell. All it did was give off a little wisp of smoke, it was a bit of an anticlimax
The LiPos that I've seen go-off in a big way are pretty much always over charged or fully charged ones that got physically damaged.

So if you store at 3.8V or so you should have much reduced potential for pyrotechnics. Anyway, compared to the hazard posed by the gas in the tank of your car LiPos are safe as houses.
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Old 10-04-2013, 05:45 PM
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For what it's worth.....I know of two flying buddies who have (had) used ammo boxes to store their lipos. Neither have (had) vents. Both are older military "surplus".......
One of the guys no longer uses such. He starting discovering a few of his "newer" 2 & 3 cells getting "puffy" after discharge while being stored in his garage. Summized that since the garage gets extremely hot in the summer months, that may have come into play. He's now using his beer fridge and Tupperware containers to store while inactive and transports them in an Igloo ice chest.
The other buddy still uses the old ammo boxes (has drilled a few tiny holes and foamed lined the inside bottoms and sides)......he also keeps those boxes stored in his "air conditioned" swamp cooled garage and uses them for transport.

I, on the other hand, do not have enough 3s or larger batteries to require that extent to store or transport.....the six I have are kept in the garage fridge and travel with me in an insulated nylon lunch box....lol. That may change pretty soon if my fleet continues to grow with 4s.....
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Old 10-04-2013, 06:06 PM
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kyleservicetech
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Originally Posted by xmech2k View Post
At first he said he was charging properly, though not balancing, at 1C. Later he realized it was a 4S batt, but he thought it was a 5S...
Nice thing about those quality chargers such as the Cellpro line.

I've operated all of them, and personally own two of their Powerlab 8's.

And, I always use the balance connection with this charger. That way, the charge automatically uses the balance cable to determine how many cells are in the battery being charged. Methinks this issue is reason enough to always use those balance cables. When setting up the balance charger processes, the Cellpro LiPo and A123 setup screens requires the battery type, charging rate, plus a few things involved with when the charger shuts off at full charge and so on. The cell count is automatically determined with the balance cable.

Almost idiot proof. Plus that balancing charge process really reduces the chances of fire while charging these LiPo batteries.

As for the Ammo box, got a question: What are the issues of fumes and what ever getting into your home if you do have a fire inside that ammo box???

As for LiPo fires, at a local clubs fun fly last year, a very nice WWII electric model got mid-aired and went straight in. Its 12S LiPo battery ignited, and burned and smoked for some 20 minutes. The club poured several buckets of sand to pour over the battery pack. That sand had zero effect on the fire. That battery just burned until it was done. The club was somewhat lucky, it missed a very large brush pile by less than 100 feet.
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Old 10-04-2013, 07:05 PM
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Last edited by Old 'N Slow; 11-17-2013 at 03:49 PM.
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Old 10-04-2013, 08:50 PM
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I have a couple of those "lipo-safe" bags from hobbyking.I wonder what happens if a pack were to catch fire inside one.They appear to be lined with some sort of cloth type stuff.Maybe kevlar?
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Old 10-04-2013, 08:51 PM
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Few points here ...

Old & Slow ... why do you mention Li Ion when the thread is about LiPO ?

Second ... to all : LiPo as many other items are capable of sustaining combustion by themselves without further oxygen. The oxygen actually only increases the ferocity of the combustion.

If we had a sealed box and LiPo fire inside ... opening the box could cause an eruption of flame as the new oxygen rich air floods in ...

Personally my charge near a window serves my idea better IMHO ... I don't like the idea of a sealed box ... with my window .... I grab the charger ... it's lead will carry the LiPo weight and it all goes out window into garden ...

Right next ... I am sure that my B6 charger will default out if I try to charge a 4S on 5S setting ... basically because it will be looking for 5S range voltage on the main charge leads ... whether the balance lead is connected or not. If the balance lead is connected - it will ALSO detect the lack of that 5th cell ... I do not have to have the balance lead connected to be safe against wrong cell setting ...

Nigel
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Old 10-04-2013, 09:04 PM
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Here is one example:

https://www.youtube.com/watch?v=OuH017ic6uo
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Old 10-04-2013, 09:29 PM
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2 ammo boxes for sale. Cheap!

Seriously, anyone know German? (I guess..) What size lipo was that? Good point, Jetplaneflyer, about stored batteries having much less energy which is good when stored, but then there's the trips to the field when they're charged. Well, I guess we just have to be as careful as possible. I'm just trying to figure out the safest way without putting tinfoil on my head, if you know what I mean.
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Old 10-04-2013, 09:38 PM
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.

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Old 10-04-2013, 09:39 PM
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4S 2500

There are two frames at the beginning with some information. I'll type them into a translator if I get a chance.
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Old 10-04-2013, 09:44 PM
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LiPo storage bags are usually multiple layers of woven fiberglass or other fire retardant materials. They are designed to contain a LiPo fire and (hopefully) keep it from spreading. You'll still get extremely hot smoke and fumes venting so it's a good idea to keep them away from easily flammable materials as a precaution.

One of the best storage solutions I've seen is a heavy ceramic container with either a loosely fitted or vented lid. The walls contain any flames and act as an insulator by dissipating the heat over a large surface. You can find sizes that allow you to use them to transport your batteries when you go flying. I've seen where people have used common unglazed terracotta flower pots with great success.

My suggestions, for what they're worth, are simple:
- Always, always, always balance charge!
- Check cell voltage before and after each charge and each flight.
- Always use a LiPo bag for charging and storage, even inside another container.
- Never store more than two LiPo batteries in the same bag.
- If you have a large collection of batteries use multiple containers to store them and keep the containers separated.
- If you ever question the condition of a LiPo battery, even for a second, replace it!
- Dispose of old LiPo batteries safely. You can find appropriate methods by a careful web search.

As with any other device for storing large quantities of energy always use common sense and basic safety practices when handling LiPo batteries!
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Old 10-04-2013, 09:52 PM
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I've mentioned this in the past but I have two storage locations in my house that let me sleep with ease. In the warmer months it is in a wood stove insert in our fire place. The other is in a seldom used oven in the kitchen. The oven is not going to be practical in some households if the cook does not approve and understand. I do most of my charging and discharging on top of the stove.
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