Lithium Battery Warning

[N162E]

I have been a member of the Academy of Model Aeronautics for......well..let's just say a long time. This is the first e-mail I have ever received from them. /ubbthreads/images/graemlins/eek.gif

EMERGENCY SAFETY ALERT

Lithium Battery Fires
Lithium batteries are becoming very popular for powering the control and power systems in our models. This is true because of their very high energy density (amp-hrs/wt. ratio) compared to NiCads or other batteries. With high energy comes increased risk in their use. The, principal, risk is FIRE which can result from improper charging, crash damage, or shorting the batteries. All vendors of these batteries warn their customers of this danger and recommend extreme caution in their use. In spite of this many fires have occurred as a result of the use of Lithium Polymer batteries, resulting in loss of models, automobiles, and other property. Homes and garages and workshops have also burned. A lithium battery fire is very hot (several thousand degrees) and is an excellent initiator for ancillary (resulting) fires. Fire occurs due to contact between Lithium and oxygen in the air. It does not need any other source of ignition, or fuel to start, and burns almost explosively.

These batteries must be used in a manner that precludes ancillary fire. The following is recommended:


Store, and charge, in a fireproof container; never in your model.

Charge in a protected area devoid of combustibles. Always stand watch over the charging process. Never leave the charging process unattended.

In the event of damage from crashes, etc, carefully remove to a safe place for at least a half hour to observe. Physically damaged cells could erupt into flame, and, after sufficient time to ensure safety, should be discarded in accordance with the instructions which came with the batteries. Never attempt to charge a cell with physical damage, regardless of how slight.

Always use chargers designed for the specific purpose, preferably having a fixed setting for your particular pack. Many fires occur in using selectable/adjustable chargers improperly set. Never attempt to charge Lithium cells with a charger which is not, specifically, designed for charging Lithium cells. Never use chargers designed for Nickel Cadmium batteries.

Use charging systems that monitor and control the charge state of each cell in the pack. Unbalanced cells can lead to disaster if it permits overcharge of a single cell in the pack. If the batteries show any sign of swelling, discontinue charging, and remove them to a safe place outside as they could erupt into flames.

Most important: NEVER PLUG IN A BATTERY AND LEAVE IT TO CHARGE UNATTENDED OVERNIGHT. Serious fires have resulted from this practice.

Do not attempt to make your own battery packs from individual cells.

These batteries CANNOT be handled and charged casually such as has been the practice for years with other types of batteries. The consequence of this practice can be very serious resulting in major property damage and/ or personal harm

Safety Committee
Academy of Model Aeronautics

5161 E Memorial Drive
Muncie, IN 47302

 

[3rd_shift]

#1 When was this info originally published?
#2 If lithium polymer batteries are so dangerous, then how have so many of us with cellphones gotten away with no problems with them?
#3 Has anybody here had problems as described in the 1st post on this thread?
If so, please let us know.

 

[N162E]

[ QUOTE ]
3rd_shift said:
#1 When was this info originally published?
#2 If lithium polymer batteries are so dangerous, then how have so many of us with cellphones gotten away with no problems with them?
#3 Has anybody here had problems as described in the 1st post on this thread?
If so, please let us know.

[/ QUOTE ]

This was put out by the AMA safety cmmittee on 4/23/04. I think the message here is that we should be careful with these batteries. Cell phones, computer packs and the packs used in cameras and camcorders all come with protection and made for chargers.

Hopefully no one in this group has had any kind of an accident with these batteries. I don't know how many members are in this group but I do know that RC enthusiasts around the world are several million.

If the admins of this group think this warning is unwarranted, feel free to remove it.

 

[3rd_shift]

I think they are going to let it stay.
My 2 cents, if the info you provided gets verified enough by many of us, this post would be a good one to stick to the top of this forum section. /ubbthreads/images/graemlins/bowdown.gif

 

[Doug Owen]

This seems a clear case of 'words to the wise'.

Many things in our lives are quite safe used in the conventional manner (like say gas for our cars), but can be very dangerous otherwise.

Few of us would promote unprotected sex just because we presonally never got HIV (or even don't personally know anyone).

IMO, a fellow who hears warnings like this and continues high risk practices while maintaining 'prove there is a threat' are asking to be that proof.

Once again, there's a clue in the fact that *none* of the Li Poly cell makers will sell end users loose cells. It's not that they don't want your money......

Doug Owen

 

[Doug S]

[ QUOTE ]
Doug Owen said:
This seems a clear case of 'words to the wise'.

Doug Owen

[/ QUOTE ]
I find that I agree with the other Doug [as I almost always do].
I do not wish to appear to minimize the hazards of improper handling of Li-ion or Li-Po cells. While another warning is probably always appropriate, there is nothing new in this one that hasn't been discussed here on the forum before.
One does wonder a bit about the depth of technical knowledge of the Academy of Model Aeronautics Safety Committee as their warning contains some misleading if not plain incorrect statements. For example:
"This is true because of their very high energy density (amp-hrs/wt. ratio) compared to NiCads or other batteries." The units shown, amp-hrs/wt. are not a measure of energy density. Correct would be Whr/wt.

"Fire occurs due to contact between Lithium and oxygen in the air. It does not need any other source of ignition, or fuel to start, and burns almost explosively"
While this correctly describes what metallic lithium can do when exposed to air, Li-ion and Li-Po cells to not normally contain *any* lithium in metallic form. It is true, however, that after severe charging abuse, some metallic lithium can be present as a product of the charging abuse. Most of the energy released in a Li-ion or Li-Po cell fire is not from the oxidation of lithium metal.

I find a few of the recommendations to be a bit extreme such as transport/storage/charging in fireproof containers, no unattented charging, etc. Nobody I know does this with their cell phones. While there is no harm in following these recommendations, if one lacks the proper knowledge/understanding/equipment to know if their charging method is appropriate and safe, perhaps they shouldn't be using Li-ion or Li-Po at all.

One recommendation made in the warning, while very appropriate should be expanded:
"Never attempt to charge Lithium cells with a charger which is not, specifically, designed for charging Lithium cells."
It should be clarified that just because a charger *is* specifically, designed for charging Lithium cells does not mean it is appropriate or safe for *your* particular Li-ion cells. One does not have to look any further than this forum to see examples of this type of error, e.g., folks charging bare cells on Pila chargers.

In summary, hazards do exist for those that do not follow the manufacturers' protocol for charging these cells. The more negative and non-PC version of this is "Morons and Li-ion should not be mixed".

 

[RussH]

While I find that the advice given is good, I find the term 'lithium battery' to be very vague. I'd like to see the answers to 3rd_shifts questions. Google didn't turn up any references to an AMA safety committee, or any such warning associated with the AMA. So it looks like disinformation. In addition to 3rds questions, I have the following questions:

1) Which types of lithium batteries are they refering to?
2) How many such incidents can they document?

This reminds me of the dangers of keeping a lighter in your pocket while welding. Do you know how many people have been injured by that?

IMHO, we really need an encyclopedic book of warnings printed on each such battery sold, along with the same for every oher kind of battery, particularly automobile lead acid batteries for which there are documented injuries.

 

[RussH]

Re my statement "Google didn't turn up any references to an AMA safety committee, or any such warning associated with the AMA" OK, I found this on AMA's site. But where is their documentation? I haven't found any reference (documented) to injuries, yet.

Re Doug S comments. I'm pretty much in agreement, especially with this one "I find a few of the recommendations to be a bit extreme such as transport/storage/charging in fireproof containers, no unattented charging, etc. Nobody I know does this with their cell phones. While there is no harm in following these recommendations," SNIP

I disagree with this part:
"if one lacks the proper knowledge/understanding/equipment to know if their charging method is appropriate and safe, perhaps they shouldn't be using Li-ion or Li-Po at all."


I don't want anyone making such decissions for me. Millions of people are using these batteries every day, and many of them don't even know what kind of battery they are using. Most of the ones who do know that they are using lithium batteries only know enough to buy a replacement.

My real objection to this is that they don't specify the types of batteries that they are refering too. This creates needless fear and confusion. And leads to such things as ALL lithium batteries being banned from aircraft. I'm all in favor of avoiding airplane crashes, but my prefered method is to stay off of them entirely. It's mostly because I hate waiting in line and being searched, tho, not a fear of flying.......

 

[hotfoot]

Hi fellas, here's my 2 cents worth.

It seems to me that Li-Ion cells are generally safe if:

- They're used with a proper matching charger that prevents overcharge and charges them at the correct rate.

- Used as a single-cell pack only (and not a multi-cell battery pack, or a bunch of loose cells connected in series). Most cellphone (and other 3.6V Li-Ion powered devices) are single-cell, where its harder to go wrong. The risk arises when the cells are used in series because the possibility of reverse charging becomes higher. For eg. a user who accidentally mixes up 3 fresh cells and 1 dead cell in a 4-cell light could theoretically reverse charge the dead-cell at >2C rate. If that rate of reverse charge were to keep up, well - that's basically what the guy who videotaped his RC-hobbyist Li-Ion pack bursting into flames demonstrated... I'm gambling that commercially-available multi-cell Li-Ion packs - like those for notebook PCs - come with circuitry that works in conjunction with the charger to suss out and prevent any likelihood of reverse-charging a faulty-cell within the pack, hence their relative safety compared to bare-bones Li-Ion battery kits and other similar casual arrangements.

- They're not damaged. A manufacturer I spoke to reassured me that Li-Polymer (ie. cellphone batts) cells are fairly safe, even when punctured - they're just kinda icky. I'm not quite 100% sure yet about Li-Ions in general, but I've had some concerns about them when they sustain damage (the most worrisome type being invisible internal damage).

Personally, I *LOVE* these Li-Ions! BUT - I would hope that everyone using Li-Ions in their flashlights or other devices (especially high-drain multi-cell setups) simply takes extra care in watching what they're doing, at least until these types of batteries are proven to be reasonably safe in widespread use and accidental abuse.

Be safe, everyone! /ubbthreads/images/graemlins/smile.gif

-Leo

 

[Doug S]

RussH, I should clarify that my comments are directed towards the "homebrew" applications, not cellphone users and such.

Regarding avoiding airplane crashes, I don't think that you are at risk as I don't think that you would fit on the airplanes of the type that were the subject of the posted warning.

Regarding lithium battery type, the original posted warning clearly indicated that they were addressing lithium polymer cells.

 

[Lux Luthor]

It would be nice to have a sticky that contains some of this basic safety information - especially given the number of Li ion/poly threads recently, and talk of the development of R123s.

 

[Ray_of_Light]

There is, I note, too much disinformation abouth lithium cells, either primary or rechargeable.
Also, there is very little education feed from manufacturers to the general public.
The results are such panic-spreading announcements.
Li-Ions are the most formidable advance in electrochemical storage I have seen in the last 30 years. The matter deserves much more respect and attention, in my opinion, from the portable appliances manufacturers, and from Li-Ion batteries manufacturers.
It is just a case, I ask, that Li-Ion and Li-Poly are not manufactured (yet) from multinational giants?

My 2 Eurocent

Anthony

 

[Kiessling]

weren't the Li-Po supposed to be safer than the Li-Ion ... or am I confusing something here?
bernhard

 

[billw]

>> weren't the Li-Po supposed to be safer than the Li-Ion ...

Being "soft", they're less likely to "explode" than Li-ion.
Being solid, they're less likely to leak nasty solvents.
So yeah, they're "safer"; I think the airplane crowd took this
overly generally, and assumed they wouldn't catch fire, either.

Fact is, i think anything with the energy density we're talking about, and the high discharge rate capability they want, HAS to be able to be a fire hazard...

BillW

 

[Kiessling]

thanx billw !
bernhard

 

[RussH]

Doug S said "Regarding avoiding airplane crashes, I don't think that you are at risk as I don't think that you would fit on the airplanes of the type that were the subject of the posted warning."

Right, well probably not. I have seen some that I might physically be able to fit into, but I think I weigh to much. There are apparently some built to carry heavy cameras that are about 1/4 scale.

"Regarding lithium battery type, the original posted warning clearly indicated that they were addressing lithium polymer cells."

I had to read it a few times but I did catch that, eventually.

It is a good point that this announcement was intended for the RC model crowd, not really the general public. They would be more knowledgable in general as well as more likely to experiment. (almost like CPF members!). But the amount of mis-information in this article still bothers me.......

I'm in agreement with Lux Luthor that a technicaly more refined (corrected & extended to similar chemistries) version would make a good sticky.

 

[dano]

Lithium is volatile, and fires from these cells (including the popular 123-size cells) is a possibility, but not something to be overly paranoid about.

--dan

 

[Neg2LED]

Laptop Lithium Ion battery packs usually have batteries in sets of three, where the cells within the sets are wired in paralell, and the sets are wired in series. also, between sets are diodes to prevent reverse charging, there is a fusable link, and also some circuitry that acts like a Pila's protection circuitry.

Neg

P.S. i found this out by oepning up 4 different lap top battery packs.

 

[dingram17]

A precaution to take with Lithium Ion and Lithium Polymer batteries is to use a Protective Charge Module (PCM). I get LiPoly packs made commercially for an application at work and they are 3xcells in series with the PCM protecting the whole lot. The PCM has over charge current, over discharge current, over charge voltage and over discharge voltage protection. When you try and do something stupid a FET effectively disconnects the cells from your device or the charger.

I'm told by my supplier than Model Aero people tend to avoid PCMs since it limits the current they can draw. Many do not 'look after' their batteries electrically. If you do, they should last well. The energy density is brilliant!

Kokam's application note is worth reading:
https://www.fmadirect.com/support_docs/item_1080.pdf


Dave.

 

[gregw]

I'm one of the RC crowd and have a number of helicopters and planes using Lipoly cells. The largest pack I have is for one of my helis, at 16.8V and 8000mah. I've been using this technology for over a year now, and so far, no issues. I think the main problem people encounter are caused when they push the cells too far below minimum cell voltage. This will cause imbalance in the pack and start the lipoly pack on the road to trouble.

The fires from Lipoly packs reported over at rcgroups.com so far, have almost all been caused by human error, where a Lipoly pack has been charged at a higher voltage than it is supposed to be.. e.g. charging a 2S (8.4v) pack as a 3S. This WILL cause the pack to overheat and eventually suffer from thermal runaway.

I doubt anyone here on this board will push Lithium cells to the extent that the RC crowd does. For RC applications, we are looking at pushing these cells up to 10C. e.g. 1000mah cells will be taxed up to 10Amps. /ubbthreads/images/graemlins/smile.gif