# LiFePO4 & Fires..????



## CMS (Jan 5, 2013)

Hi Guys,

I have looked high and low and not seen evidence of LiFePO4 batteries catching fire? 

I have seen & read of BMS systems that have caught fire or shorts etc. but do any of you know of any cases of LiFeP04 cells catching & sustaining a fire like the Boeing incident, or like the Sony computer Li batteries? Can anyone point me to these incidents if in fact they have happened?

Seems "li" technology takes a hit in circumstances like the Boeing incident and that would be unfair to other Li chemistry batteries if they do not suffer the same types of catastrophic events.

Thanks,

CMS


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## Ziggythewiz (May 16, 2010)

I think Jack R. burned some A123s on a test bench. He blamed it on a BMS but didn't really explain it.

There was also the BYD taxi fire, but not much won't burn if you try to cut it in half with a tree after a 100+ mph crash.

And the 16 Karmas from TS Sandy plus shady details in other Karma fires.

Oh, and some guy likes to burn wrenches with the new CALB CAs.

I don't read much into ANY specific example. There's cell chemistry, packaging, BMS, enclosure, charge/discharge profile, HVAC, and natural disasters all to consider.


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## Zak650 (Sep 20, 2008)

Ziggythewiz said:


> I think Jack R. burned some A123s on a test bench. He blamed it on a BMS but didn't really explain it.
> 
> There was also the BYD taxi fire, but not much won't burn if you try to cut it in half with a tree after a 100+ mph crash.
> 
> ...


Jack burned some A123 cells by putting them on a power supply to charge them and then got involved with something else, forgot about them, and they eventually went up in smoke. They looked very much like Jiffy-Pop. I've never heard of a non-bms lipo4 pack that's been burned up while attached to a working charger. If anyone has experience with this would be good to know.

I don't have any knowledge of the boeing fires but I'd bet they had some sort of bms attached to them, almost all "sophisticated" systems do.


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## Elithion (Oct 6, 2009)

CMS said:


> I have looked high and low and not seen evidence of LiFePO4 batteries catching fire.


Fire? Not exactly. More like explosions and or lots of white smoke. But not actually flames. 

I have seen it happening, and I have seen the results after the fact. In all cases, it was due to abuse of the battery. Some examples.


Shorted the 2 battery output cables during manufacture (seen it twice)
Two shorts to chassis, completing the circuit (seen it once)
Loose battery connection, arching, nearby combustible materials catch on fire, heat pops the LiFePO4 cells (seen it once)
Outboard charger left on overnight, no BMS control (seen it once)
Boat captain connecting over-discharged and damaged Li-ion batteries in parallel to fully charged ones (seen it once)
On purpose, for testing



CMS said:


> like the Boeing incident


The Boeing Dreamliner incident was not LiFePO4; it was LiCoO2 (standard Li-ion).



CMS said:


> I have ... read of BMS systems that have caught fire.


Not once. Every report I have read about that was generated by a party which may have had some interest in saying so. I am not saying that it's impossible, I am just saying that I have no reliable knowledge of any such case. 

But you say that you have seen it yourself: by all means, please elaborate (with verifiable details, if possible), as I really need to know about it.


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## CMS (Jan 5, 2013)

Elithion said:


> Fire? Not exactly. More like explosions and or lots of white smoke. But not actually flames.
> 
> I have seen it happening, and I have seen the results after the fact. In all cases, it was due to abuse of the battery. Some examples.
> 
> ...


Davide,

Thanks for chiming in.. I have not "seen" any BMS cause a fire. I have read "on the net" where people claim the fire was cause by a home made BMS or the shunt got too hot etc. etc... 

So these batteries can have issues, but it seems, from your examples, you really need to do something to move it along to that level... When you say "explosions" what precipitated those events?


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## Elithion (Oct 6, 2009)

CMS said:


> So these batteries can have issues


Not as many as LiCoO2. LiFePO4 can handle much higher temperatures before going ballistic (literally) than LiCoO2. That's why LiFePO4 cells are considered safer.



CMS said:


> When you say "explosions" what precipitated those events?


The list I have above. For example, the first item. Numbnuts engineer runs power cable from battery through uninsulated 1" braids. Braids touch each other. Loud pop. White smoke. Crackling. 
Battery is on a wheeled cart, next to a sliding door to the outside.
In 5 seconds (literally) people open the doors, push the cart out.
Call the fire department. 
Battery starts popping loudly.
Small cylindrical cells blow their top (so much for the safety vent being a good solution) like projectiles, way in the air, and onto the roofs of the nearby buildings (the Quizno's in this picture).


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## PStechPaul (May 1, 2012)

Have there been any incidents where the BMS was working properly and the cell still failed catastrophically? And what would it take to contain such an explosion and fire and prevent other cells from joining in the fireworks?

I'm considering a battery pack consisting of probably 100 Li-Ion or LiFePO4 cylindrical cells (18650) in series for 320V or so, and I would like to be prepared for a destructive battery event, especially since I may use the cheap "ultra-fire" type cells if they test close to specs. I am considering enclosing each string (perhaps 10-16 in series), in a clear polycarbonate tube, which is pretty strong but only good to 200F. So I may also wrap them in a high-temperature fabric such as Nomex or Fiberglass:

http://www.mcmaster.com/#fabric/=l4jocn (Vermiculite-coated fiberglass, 1500F, 0.020 thick, about $2/sqft)
http://www.mcmaster.com/#catalog/119/3555/=l4k4zc (Lexan tube, 3/4ID, 7/8 OD, $2.71/ft)

Seeing the example where the cells blew their tops, I would mostly need to contain them in that direction, along the axis of the stack. I think I could provide end plates for the pack assembly made of steel or aluminum and perhaps some strong neoprene foam to exert some pressure on the stack to maintain connection and allow some expansion while absorbing some of the energy. The entire pack would be about 30" long for 10 18650 cells, and about 6" x 2" for a 5x2 matrix of 7/8" diameter tubes. This would be, "potentially", a 3.2Ah 370V pack or 1.2 kWh, and would cost about $240 for the Li-Ion cells. The enclosure and the BMS will probably cost twice that. I'm willing to use Li-Ion if I can be sure that the BMS and the enclosure will make it safe. I am not as concerned with reliability as it will be used in a lawn/garden tractor.


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## Caps18 (Jun 8, 2008)

Jack (EVTV) and his partner in crime that does the extreme battery testing is a good start. It is nice to know that shorting out one cell won't cause it to spontaneously combust, but what if you have 45 of them wired together...

Also, what if they are in an tightly enclosed container on a hot day, what temperature range will cause problems?

If it works fine at 60 C, what is the failure temperature and what will happen? I would like to know what the limits are to know where I can't exceed.

I think that LiFEPO4 batteries are a good technology, but there is a bunch of engineering tests that are missing from the public record. The battery manufacturers or suppliers aren't doing that great of a job coming out with guidelines for how to use the batteries, what not to do, and how to wire them up.


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## Elithion (Oct 6, 2009)

Caps18 said:


> shorting out one cell won't cause it to spontaneously combust, but what if you have 45 of them wired together.


Exactly the same result. 
Think about it this way: 


 A single cell sources x Amp through a short circuit
Two cells in parallel source 2 * x Amp through a short circuit, but each cell sees 1/2 of it, so, x Amp
45 cells in parallel source 45 * x Amp through a short circuit, but each cell sees 1/45 of it, so, x Amp
Sure, the point of short circuit sees 45 * x Amp; but the voltage across it is 0 V, so the power is also 0 W. All the heat is in the cells themselves, and it's evenly distributed.


The bigger the cell, the more short circuit current it can source, but its volume is also bigger, so it can handle more current. It makes little difference whether it's a cell that is 45 times as big, or 45 small cells in parallel.


(Yes, on a second order, there are thermal differences, but a short circuit discharges a cell very quickly - 20 seconds to 4 minutes, almost faster than cooling effects.)


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## Ziggythewiz (May 16, 2010)

Caps18 said:


> Jack (EVTV) and his partner in crime that does the extreme battery testing is a good start. It is nice to know that shorting out one cell won't cause it to spontaneously combust, but what if you have 45 of them wired together...


When did Jack hard short a cell? I'd like to watch that one. Someone should compile a list of high voltage/current events for extreme viewing pleasure.




Elithion said:


> Exactly the same result.


Not necessarily. A single cell that's shorted is making lots of heat, but in a full box of cells that are shorted will be subject to much more heat. The one in the middle will get 5x as much.

As for the series string voltage, it's not 0W being dissipated and it's not all internal, otherwise no wires would ever melt. Also, there is a big difference between a shorted condition and the act of shorting. It begins as a high voltage/current event and is likely accompanied by plasma or other destruction.


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## Elithion (Oct 6, 2009)

You are correct in all you say. 
But that was not the question I was answering. The question that was asked was about shorting a cell. A short is a short is a short, and has 0 Ohm, and therefore 0 W. 
In reality, what you describe is more likely that a 0 Ohm short. So, yes, I very much appreciate all you say there.


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## Jan (Oct 5, 2009)

Elithion said:


> A short is a short is a short, and has 0 Ohm, and therefore 0 W.



Eh, you mean infinite W?


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## Elithion (Oct 6, 2009)

jan said:


> eh, you mean infinite w?


 Power = i^2 * R = i^2 * 0 = 0 W


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## GerhardRP (Nov 17, 2009)

Elithion said:


> Power = i^2 * R = i^2 * 0 = 0 W


That is externally delivered power. Internally, the battery resistance converts V^2/R watts into heat.


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## Jan (Oct 5, 2009)

Elithion said:


> Power = i^2 * R = i^2 * 0 = 0 W


I think that I is irrelevant at zero ohm. Or olso infinitive. 
On the other hand we know the exact value of U. 
Which leaves us with the more useful P=U^2/R. With R->0 

Luckily we mortals never have to work with zero ohm, so lets take a more realistic 0.001 ohm. P=3.2^2/0.001 = 28kW. Neglegting sag.


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## jeremyjs (Sep 22, 2010)

Ziggythewiz said:


> When did Jack hard short a cell? I'd like to watch that one. Someone should compile a list of high voltage/current events for extreme viewing pleasure.


I don't think jack ever did it on camera. There is that guy that shorted a couple of CA cells and posted it on youtube.

https://www.youtube.com/watch?v=lyYfFeWwd9I


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## Ziggythewiz (May 16, 2010)

Yeah, I've seen those, but even that's not a direct short. His tests are great for seeing what the cells can dish out, but don't tell you anything about their safety because most of the heat is going into the molten wrench or boiling water.


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## PStechPaul (May 1, 2012)

It's true that a short is never 0 ohms. There is always some resistance (except at cryogenic temperatures) and inductance (which will limit how quickly the current can change). As the temperature of the conductors increases, the resistance will also increase, lowering the current and increasing power. It is rare for an externally applied short to be very low resistance, since the point of application will get very hot and possibly arc and become intermittent. The battery has internal impedance which can be estimated by the amount of external resistance required for its terminal voltage to be half of normal, so a 100 Ah battery might be rated for as high as 50C or 5000 amps, at which point its voltage would be about 1.8V so its internal resistance would be 360 uOhms, and the power dissipation would be 9000 watts in the battery and the load. The maximum power with a true short might be 10kA at 3.6V or 36 kW. The energy of the battery is about 360 Wh, so at 36 kW it would be depleted in 0.01 hours or 36 seconds. Plenty of time to do lots of damage!


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## frodus (Apr 12, 2008)

PStechPaul said:


> a 100 Ah battery might be rated for as high as 50C or 5000 amps, at which point its voltage would be about 1.8V so its internal resistance would be 360 uOhms, and the power dissipation would be 9000 watts in the battery and the load. The maximum power with a true short might be 10kA at 3.6V or 36 kW. The energy of the battery is about 360 Wh, so at 36 kW it would be depleted in 0.01 hours or 36 seconds. Plenty of time to do lots of damage!


That power is 9000W for the battery, 9000W for the load.... for those reading. 

Battery power dissipation due to internal resistance:
5000A and 0.00028ohm would be P = (5000^2)*0.00036 or 9000W

Power to the load:
1.8V * 5000A = 9000W


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## PStechPaul (May 1, 2012)

This is at the point of maximum power transfer. At higher or lower external resistance, you can get higher voltage or higher current, but the power will be less. This is a principle of impedance matching.


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## Caps18 (Jun 8, 2008)

Ziggythewiz said:


> When did Jack hard short a cell? I'd like to watch that one. Someone should compile a list of high voltage/current events for extreme viewing pleasure.


http://www.youtube.com/watch?v=ZUOuInwMXyo

Go to the 1 hour and 2 minute mark.

There was another one from a few months ago with the same guy...

---------------

Fast Charge Test

http://www.youtube.com/watch?v=1BS3F0gpEkg

At the 46 minute mark (really starts at 1 hour & 12 minutes)


This kind of experimentation is great, but I just want to make sure that there aren't any 'accidents' when my batteries are left on a charger overnight (overcharging), that accelerating quickly in the middle of the Summer in an enclosed box won't cause them to melt, that running the car when it is -10 C outside is fine, and that charging from a J1772 plug or a 120V outlet will work just fine... This is the $6,000 part and everything has to go right the first time.


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## PStechPaul (May 1, 2012)

Fascinating video of the 1500A test. Looks like a 0.7V drop so cell internal resistance is about 467 uOhms and external resistance is 1667 uOhms. So if this cell is 170 Ah at 3.2V or 544 Wh it would produce 3.2/0.467 = 6850 amps into a solid bolted short and 21.9 kW. Thus short discharge time would be 0.025 hours or 89 seconds. This about matches the Realforce Prism in the middle of the chart. 

The fast charge at 3C was also very informative. Good stuff! I'll have to watch more EVTV, but I can see that it may be even more addictive than this (and other) forums.


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## Elithion (Oct 6, 2009)

Yes, I came up with the same value for resistance. I am thinking that it's so low because the cell gets so hot under those conditions. 
But the Short Discharge Time is at 25 °C; so, do you think it would be unfair to use that low value of resistance to calculate SDT?


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## Caps18 (Jun 8, 2008)

I actually hadn't watched the fast charging one until now. It went on for an hour and a half... so I didn't get much done tonight. But, I learned about the battery that I am going to use. Keep it between the 95% and 30% charge level and everything will be great, and you can throw as many DC amps of power at your battery as you can without a problem. 

I would assume that AC amps would be similar, but even with a J1772 plug @ 30A-40A /240V it shouldn't cause any problems for the LiFePO4 batteries. I figure that to put 10,000W in my truck would take about an hour and a half anyways at 40A/240V and a PulsaR charger that they claim is up to 24kW...but 6.6kW is more common.


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## GerhardRP (Nov 17, 2009)

The Cessena battery incident involved LiFePO4 batteries, but unfortunately there seems to be no public information about what actually happened: Cessena and A123 issued an immediate recall, rubber stamped by the FAA which short-circuited an official investigation.

http://macsblog.com/2013/01/battery-problems/
http://saeaero.saejournals.org/content/3/1/149.abstract


CMS said:


> Hi Guys,
> 
> I have looked high and low and not seen evidence of LiFePO4 batteries catching fire?
> 
> ...


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## pdove (Jan 9, 2012)

They definitely burn don't be fooled. It is usually the BMS at wee hours of the morning that cause it.

Don't top balance cells it is dangerous.
http://www.batteryvehiclesociety.org.uk/forums/viewtopic.php?t=1825


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## Ziggythewiz (May 16, 2010)

pdove said:


> Don't top balance cells it is dangerous.


Yes, much better to bottom balance and then overcharge them.


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## ToolClerk (Mar 17, 2016)

I had a fire in my lifepo4 battery but all that burnt was bms and all the wiring ,the seller Ibattery on Ali Express,sellers name ENGD probably not his real name and he said he would replace or fix but then became non existent for replies,I contacted manufacturer Codd Battery(Eddie)www.lifepo4.in and they said they would give battery than became non existent,there was no damage to battery cells but the wires and duct tape burnt crispy,It was a 72V 20AH in an electric bike but to watch 1200.00 go up in flames aint easy,I had always heard lifepo4 was safe from fires but this surprised me ,my reason for posting is to warn buyers to check out where they are purchasing batteries as there is crooked sellers selling from china and telling customers fairy tales,remember the names and companies I wrote here as you would be best of avoiding them ,as well as many other Chinese sellers when it involves expensive electronics,we are better off purchasing cells and BMS and building ourselves as my battery caught fire from there inproper wiring as when I received battery the BMS was shutting down on acceleration and the seller told me to discharge without the BMS and use for charging,that was seller had sent defective product and was avoiding fixing as I would find out when fire happened,there is more and more lithium batteries being used and there is going to be deaths sooner or later


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## pdove (Jan 9, 2012)

ToolClerk said:


> I had a fire in my lifepo4 battery but all that burnt was bms and all the wiring ,the seller Ibattery on Ali Express,sellers name ENGD probably not his real name and he said he would replace or fix but then became non existent for replies,I contacted manufacturer Codd Battery(Eddie)www.lifepo4.in and they said they would give battery than became non existent,there was no damage to battery cells but the wires and duct tape burnt crispy,It was a 72V 20AH in an electric bike but to watch 1200.00 go up in flames aint easy,I had always heard lifepo4 was safe from fires but this surprised me ,my reason for posting is to warn buyers to check out where they are purchasing batteries as there is crooked sellers selling from china and telling customers fairy tales,remember the names and companies I wrote here as you would be best of avoiding them ,as well as many other Chinese sellers when it involves expensive electronics,we are better off purchasing cells and BMS and building ourselves as my battery caught fire from there inproper wiring as when I received battery the BMS was shutting down on acceleration and the seller told me to discharge without the BMS and use for charging,that was seller had sent defective product and was avoiding fixing as I would find out when fire happened,there is more and more lithium batteries being used and there is going to be deaths sooner or later


You had a BMS fire not a battery fire it sounds like to me. If the batteries are fine then you did not have a battery fire. In my observations it is usually the BMS that causes to fire. A cell level BMS is not necessary with LiFePO4 cells.


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