Lipo fire

[fly boy3]

Was told that a crash damaged Lipo burst into flames days after the crash. Luckily it had been removed from the model prior to the fire, and no other damage occured. Can this be right ? Cheers

[scott finnie]

After seeing some violent lipo incidents i'd say yes, i havent seen any burst into flames just by sitting but i have seen several that appeared fin after a crash then blister up a few days later. I now keep my lipos in a lipo bag and that is then placed in a fire retardent safe just for extra security and safety whilst out

[fly boy3]

Thanks Scott. Do you recommend that all lipos are removed from models, and kept in the same conditions as you mentioned in your post ? Thanks

[Bandit]

Don't leave Lipo's in models.

It is good practice to take them out and store them as Scott suggests.

Taking the Lipo out also makes sure it is disconnected as I have heard of someone forgetting the lipo was in the plane.

[Simon Chaddock]

FB3

A LiPo contains a lot of electrical energy. Its polymer electrolyte is flammable. Its casing is plastic.

Consider it like a similar sized plastic bottle of petrol. Safe enough even in the presence of a naked flame but don't mistreat it.

On the other hand a crash damaged LiPo is rather like striking matches close by a leaking plastic bottle of petrol.

Crash damage does not have to actually pierce the casing. If its structure is damaged it can internally short circuit which releases enough heat to melt the casing and ignite the electrolyte. The cell then starts a 'runaway' process completely destroying itself in no more than a second.

[fly boy3]

Hi lads, as you have probably guessed, I am new to Lipos, only have 2 electric models and 3 Lipos between then both. After reading these posts they are in a safer place, but will have to buy a lipo bag asap. Thanks

[fly boy3]

Wonder if this is suitable for charging and storage of a few lipos. Thanks http://www.giantshark.co.uk/product/170661/lipo-charge-safety-bag-23x30cm

[scott finnie]

Posted by fly boy3 on 14/01/2014 17:13:16:

Wonder if this is suitable for charging and storage of a few lipos. Thanks http://www.giantshark.co.uk/product/170661/lipo-charge-safety-bag-23x30cm

Thats the ones i have and they are worth it for there price . Yes as Bandit said never leave them in a model, to be honest store them as far as you can from them and dont have them anywhere near where nitro fuel has been either. I'd much rather a smoldered safe than my garage and pride of joy's burning up. I had a lipo fire onboard a parkzone Albatross last year and even after ditching it into a pond it continued to burn under the water! As has been said they really do have alot of energy within waiting for that moment to escape. I just got rid of 6 old 4s lipo's , i cut there leads, placed them in water for a few days then took them to my local recycling centre. I have a seperate lipo bag for each battery, the last thing i'd want is one going on fire and destroying £200 worth of batteries. This is the safe i use too which is cheap and does the job nicely **LINK**

[fly boy3]

Thanks Scott, taken all what you have said on board, and will act on it. Cheers also thanks to Simon, for putting this  into perspective.

Edited By fly boy3 on 14/01/2014 19:00:46

[Delta Foxtrot]

Hi fly boy 3,

I can also recommend ammo boxes which can be bought for about 12 pounds. I have a few of these for storage of lipos, recently bought a couple designed for 37 mm batton rounds which came with really useful foam inserts with holes that will fit 2200 mah 3s packs in very nicely.

http://www.denbigharmysurplus.co.uk/army-stores/Ammo-Box-37mm-Baton-Rounds.html

I drill a couple of 1.5 mm holes in the sides to relieve pressure should a battery catch fire.

cheers

dave

[Max50]

At the moment i keep my lipos in lipo bags ,all together, and stored in a metal toolbox , and in the house. The only other place is an old garage which is cold and damp and separate from the house. Should i still keep them in the house, or buy a cabinet and store them in the garage with the car? .I have about 10 in the box at the moment but maybe getting more.

Where do you all keep your lipos ? . Like ; model shops, i assume keep theirs together in their store rooms in the shop, in maybe the centre of towns.

Thanks Dave for the Denbigh Army Surplus link. Very usefull.

[John F]

This is not a winge but a serious question. Is all of this simply not just acting on hearsay, rumour and dangerous experiments on youtube?

The way some store their batteries you'd think they were UXB's. Should this only be a precaution if the battery is damaged? Surely if something was so inherently dangerous as to need a flame proof bag and fireproof box it would not be on the market?

Researching away from the hype of RC websites the advice seems to be store in a cool place 50% charged (ish). There is no mention of any dangers thereafter, unless a pack is severely damaged.

[Olly P]

John - I can't agree more - the key with undamaged LiPos is to prevent over or under charging them - 70% is a good storage level of charge, as this means temperature effect is unliely to cause an over volt situation.

it is also quite quick to top them up for flight.

I keep mine in an aluminium flight case, all together and arranged for easy use. just be sensible. if they are damaged then obviously dispose of in a sensible manner, fully discharge and use local recycling facilities to ensure proper disposal.

[will -0]

John, it's a classic case of risk and hazard:

 

The risk (chance) of a fire is relatively low statistically. There must be millions of the things out there and given that we hear relatively few reports of fires.

The hazard (danger) is however very high: it could burn your house down and you might lose everything/put lives at risk.

Given a low (but not negligible) risk of a catastrophic event, a cheap precaution such as a lipo bag is very good insurance!

Edited By will -0 on 15/01/2014 09:53:34

[Bob Burton]

Has anyone here got any experience of a Lipo bag being used in 'anger', ie, the Lipo(s) inside it caught fire for whatever reason ?

I keep my Lipos, admittedly only 2 and 3S low capacity ones, in the detached garage. They are in a shallow terracotta flowerpot but that is the only precaution I take when charging or storing them. I store them at about 3.8V per cell and charge at a maximum of 2C, usually less so they are fairly well treated.

I have been considering getting and using a Lipo bag or two but do they actually provide any protection and, if so, how ?

[Dave Miller]

On the grounds that you have to keep the things somewhere, as well as transport them and also considering that they are expensive, so worth looking after, then storage/transporting in an ammo box or similar is as good as anything. These batteries are as safe (maybe safer) than stored liquid fuel, the danger may come when charging them incorrectly or following physical damage.

It should be remembered that trying to put out a Lithium fire with water does not work it needs to be smothered.

Now I know that I’m always pointing to THIS SITE but that’s simply because it contains a wealth of sound information in the form of pdf's that are worth downloading and reading – as well as providing good service.

[Delta Foxtrot]

Spot on Will-O and Dave.

Risk = Low (if handled properly), Consequence = Potentially very high, Cost of mittigation = peanuts.

I do not have a garage or shed suitable for charging up my Lipos so I do this inside the house, but never leave the batteries unnattended. I bought a larger ammo case in which I place my chargers and LiPos during charging and this itself is placed on a fireproof surface (fireplace, fire not in use). My reasoning is I can put the lid on in case of a problem, uplug the chargers and take this outside away from the house. Apart from fire considerations , I would not want to have the highly toxic smoke inside the house in the event of a failure.

Once charged the LiPos live in ammo cases in our small garden shed. I split them between 4 cases just to limit my losses if the very unlikley occurs.

I can recommend Andrew Gibbs guides on LiPo's and other aspects of electric power.

Dave

[Simon Chaddock]

LiPo batteries are NOT solid blocks of lithium or anything like it so the concept 'a lithium fire' can be misleading.

The lithium equivalent content of a cell in grammes (as used by UPS in the US to determine if it is considered a hazardous load) is the cells capacity in Amp hours x 0.3.

So a 3000mAh cell contains the equivalent of just 1g of solid lithium.

[Rob43]

Bob, I have not seen a lipo burn inside a lipo bag, but I have seen my burst lipo discharge heat/flame/smoke and lipo bags are normally manufactured from nomex (this is the product that race car drivers suits, underwear and helmet linings are made from) which will not support combustion. It would contain the combustion and as they are flexible wont allow an explosion like a closed solid container but they will vent a large quantity of toxic gases so still a good case for outside charging. I do charge lipos in my car in a lipo bag but only whilst no one is in it. Even a small lipo would fill a car with its discharged gas.

[Dave Miller]

Posted by Simon Chaddock on 15/01/2014 12:44:05:

LiPo batteries are NOT solid blocks of lithium or anything like it so the concept 'a lithium fire' can be misleading.

The lithium equivalent content of a cell in grammes (as used by UPS in the US to determine if it is considered a hazardous load) is the cells capacity in Amp hours x 0.3.

So a 3000mAh cell contains the equivalent of just 1g of solid lithium.

The concept is not misleading Simon, to say that it is, is misleading. I have no idea how much or how little flammable material Lipo's contain but I do now that they can burn extremely fiercely so that aspect should not be understated without overstating the risk.

[fly boy3]

Hi David, great web site re ammo boxes, should have an order from me soon. Thank you. I think this thread has taught us newbies to lipos a lot, and to the experienced lads out there a little reminder to the dangers. Thanks

[Delta Foxtrot]

No problem fly boy3!

[Erfolg]

I think we would all agree that lipos can contain a lot of energy. Although I would not overstate how much. Certainly weight for weight less than Petrol or methanol. In principle less than a 4 oz fuel tank of energy in most cases.

I must applaud Simon attempting to put a value on how much lithium is in a Lipo. Perhaps a chemist amongst us can calculate how much energy the molar weight of lithium etc actually releases. There is far to much emotion and to little fact in the general Lipo risk debate.

Grabbing hold of anything burning anything is going to damage you.

I can see the benefit potentially from a bag to contain a malfunctioning Lipo. I am not sure that a metal box and a Lipo are ideal. I can see the metal box potentially increasing the potential for increasing the risk.

We certainly need to handle our Lipos responsibly, we also need a more structured approach as Simon is attempting to start. It is all well and good to say that a Lipo fire can not be extinguished by excluding air. If this is so, is that for 2 seconds or 5 minutes. A knowledge of the chemistry during combustion. What we need is a chemist, not a generalised statement which may or may not be correct. We need to have a similar review as was undertaken in the early years of Nicads, when there was a hysterical reaction to there use, before it became apparent that with the right kit and careful handling, they were not a ticking time bomb,

[Kelly]

I wonder if any model shops have a problem with Lipo's ?

If you think of the large stock, no fire proof storage seems to be used.

My local shop has a large quantity hung in pastic bag packaging behind the counter.

I do not think they put them in fire proof storage at night?

Most fires seem to occur during charging after some sort of damage due to a crash, or mishandling of some sort?

I wonder if they are safer than we are led to believe

[Pat (rActive) Harbord]

I have to agree with Kelly. I've never managed to cause a fire and I've been mistreating lipos since they came out . I do get the odd puffed cell and a 3 cell that reads as a 2, but it's ok, they are relatively cheap to not too much to worry about.

Charge carefully (read the specs) with a good charger, check discharge with a watt meter and you won't go far wrong