Nasty LiPo fire

[EBJ]

Aww, Dave, I wanted them to learn the hard way.

You are absolutely correct though, the more you try to contain an energy release you can't stop, the more danger you create.

and the more entertaining your youtube videos become

 

[karma]

ya sealed containers sounds dangerous. i ordered a few fire proof bags and made my own container hopefully i never get to find out if it works well :wink:
these bags are hard to works with. try sowing them by hand

[youtube]7IgxzyyfxXU[/youtube]

 

[bigmoose]

Aww, Dave, I wanted them to learn the hard way.

Yep, but I don't want it to be as hard for them as for me! Ol' guys tell stories to help the newer guys at the plate... :wink: was 1978ish, a nice warm night in July... when the detonation happened. Linda was 8 feet to my left, she dropped as the piece of shrapnel entered her fore arm and bounced up her arm wedging in her elbow. Al was 5 feet to my right and got hit below his manhood, the shrapnel nicked his right femoral artery... I got out of it with a 60 db hearing loss in my right ear... and knowing Someone had looked out for me that night... 8)

 

[Kepler]

Obviously a dangerous test which is why I asked Luke to do it. We all know he laughs in the face of danger

Seriously though, I do think it needs to be tested in a controlled manor i.e. some sort of bunker.

Does a LiPo fire need air to burn or does it vent its own oxidizer? I was under the impression that it needed air to burn and as such if contained in a sealed amo case, possibly the results could be quite anti climatic.

 

[Icewrench]

Steveo did some research....

http://endless-sphere.com/forums/viewtopic.php?f=14&t=8571&p=130332&hilit=lipo+fire#p130332

 

[amberwolf]

Obviously a dangerous test which is why I asked Luke to do it. We all know he laughs in the face of danger

And someday danger will stick it's bony head out of that closet door when he pulls on the rope, and try to bite his hands off. Just have to hope he's still fast enough to get out of the way.

Does a LiPo fire need air to burn or does it vent its own oxidizer? I was under the impression that it needed air to burn and as such if contained in a sealed amo case, possibly the results could be quite anti climatic.

AFAIK it vents it's own, the only thing needed is an ignition source.

And the funny thing about that, having a lot of stored power in these little layers of metal and insulator mixed in with that fuel, too.

But even if it does not, the pressure from the expelled gasses and heated air in the sealed container could cause it to burst. If it happens fast enough and the container doesn't deform around it, and vent, pressure may build up enough to shrapnel the container even without any flame.


BTW, my own "old guy's story" is that when I was just out of high school, I visited a friend in the country near KC. We cleaned out an old barn on his new property, and were sorting thru the containers. He decided to burn a bunch of old trash and boxes, and then got stupid and started just tossing any old container on there even without checking. One was a bucket of bullets and stuff....you can figure out the next event.

When I saw him do that I ran and yelled at him to run, but he didn't until the first explosion. After I had made it behind another small wooden shed, there were many SPANGs of bullets and shells and other shrapnel flying off and hitting the barn and other structures, and then there was suddenly a hole not too far from me in the back wall of the shed I was behind (laying flat on the ground).

Somewhere around here I still have the (I think) 30-06 shell that had been propelled thru two wooden walls and still travelled a few feet further to land behind me. It looks like Elmer Fudd's shotgun after Bugs plugs the end of it.

 

[auraslip]

I'll be the first to say I told you so......... but can we not do this lifepo4 vs. lipo thing? Can we just decide that all batteries are dangerous and we need to take precautions?

If we don't start taking this shit serious, some one is gonna die. And then what? Apartments will ban ebikes? Air shipments will be stopped? We won't be able to bring electric vehicles into public parking structures? Ya'll know politicians and the media can whip up a frenzy about things they don't understand. Safety should be priority one! Even if the risk is 1 in 1,000. How many people just throw their lipo bricks in a bag loosely so that they can jostle around? How many people have no fuses on their packs? How many people have zero impact protection? Far, far too many.

Two days agoI started a post asking for help building a large lipo pack safely and got only a tiny bit of feedback.

I hope some of the guys with more experience here will cut this lackadaisical approach to handling our batteries at the bud while we still have a chance.

 

[EBJ]

Steveo did some research....

http://endless-sphere.com/forums/viewtopic.php?f=14&t=8571&p=130332&hilit=lipo+fire#p130332

LiveforPhysics:

You mentioned wrapping a pack in "1/2" thick nomex pad cloth" and claimed that wouldn't allow the lipo to catch fire.
Just wondering:

1. did you ever test that theory?
2. where do you find 1/2" thick nomex?

I found this in a quick google search: http://www.signwarehouse.com/SE-GEO-KNIGHT-ACCESS-p-SE-GK-RMN-1620.html?fe_feedid=151&fe_code=SE-GK-RMN-1620&utm_source=googlebase&utm_medium=CSE&utm_campaign=feedexact
not 1/2" thick though.

Just wondering if something of this sort would work at containing flames if you placed it just over the vents on a sealed battery box ? (that way you wouldn't need more than just a few inches of the stuff to cover the "breather holes" / vents. ?????

 

[neptronix]

You have a great point Auraslip.
I personally still believe that lipo is still safe if packs are tested at first, and then not abused after.

I had one pack out of 13 packs ordered pull this crap on me:

Mind you, this happened after 0 cycles and no interaction with my lipo charger whatsoever.. The pack arrived at my house and sat there for 2 months unused.
Voltage across the pack was 3.85v +/- 0.01v.

Noticed the puffing, then left it outside in a flame proof bag, and it deflated itself with no flames.

If i had charged this pack, i would have probably had a John in CR or Kepler event, since this cell probably internally shorted due to a factory defect.
It was not puffy when i first received it from Hobbyking.
The pack was not dented or otherwise damaged.
How could i have known that this pack would have turned into a flamefest? I live in an apartment and my girlfriend was scared to shit about my other lipos, insisting that we get some kind of insurance. :?

Mind you, i have dropped packs, put them in enclosures where they bang up against the frame, overdischarged them, etc. No pack puffed up and vented like this.

I still believe lipos are safe, but i don't advocate that people use them unless they understand what can go wrong, how it can go wrong, and how they need to be treated to prevent things from going wrong.

Not trying to start a lifepo4 VS lipo war either. Oatnet had an interesting point about the weight that was worth investigation though. With those cells, the cost VS weight VS discharge rating benefit starts to narrow and the A123's start looking like a damn good alternative.

 

[John in CR]

Please, anyone who has a lipo fire in public, say that it's an experimental gasser bike, or some kind of Apple iBike with lots of computing power aboard. Don't mention anything about ebikes.

Knoxie,
Batteries duct taped to bike frames can be absolutely safe, especially compared to some of the metal lipo bombs I've seen, or crazy stuff like heat generating controllers enclosed with batteries, and the ridiculous number of ebikes around here that don't even have fuse protection.

I definitely agree that all the disconnecting and removal of batts from a bike increases risk at least an order of magnitude. That also goes for all the connecting and disconnecting for charging too though, especially with those tiny balance tap connectors. I don't understand how the lipo club puts up with all that pain in the butt stuff for charging. Park, connect a single plug, and push a button to charge makes an ebike a wonderfully convenient vehicle.

 

[neptronix]

I definitely agree that all the disconnecting and removal of batts from a bike increases risk at least an order of magnitude. That also goes for all the connecting and disconnecting for charging too though, especially with those tiny balance tap connectors. I don't understand how the lipo club puts up with all that pain in the butt stuff for charging. Park, connect a single plug, and push a button to charge makes an ebike a wonderfully convenient vehicle.

+1 +1 +1. Drop them once, and you have created a firebomb that you had been trying to avoid the entire time.
Use a weird charging setup, and you increase the room for charging error.

This is how it should be done, 95% of the time ( other 5% is when you need to occasionally balance charge ):

 

[flathill]

As batteries get better and better in the future (read higher energy/power density) the hazard will only grow, no matter the chemistry. Imagine having a 10Ah 18650 cell with super low IR...The superiority of Tesla's small cell form factor approach from a safety standpoint will become more and more apparent

http://www.teslamotors.com/display_data/TeslaRoadsterBatterySystem.pdf

 

[Hillhater]

...The superiority of Tesla's small cell form factor approach from a safety standpoint will become more and more apparent...

Its not just the small form factor,..they have "cell level" safety features also ...

The cells used in the Tesla Roadster all have an internal positive temperature
coefficient (PTC) current limiting device. The primary role of this PTC is to limit short circuit
current on an individual cell level. It is important to note that this device is completely passive
and functions without any inputs from the rest of the battery pack systems.
A second level of protection is provided by the Current Interrupt Device (CID). Each battery cell
used in the Tesla Roadster has an internal CID. These devices serve to protect the cell from
excessive internal pressure. In such a case the CID will break and electrically disconnect the cell.
High internal pressure is generally caused by over-temperature or other failures that then result in
over-temperature.
The cells also incorporate numerous mechanical, thermal, and chemical factors that contribute to
their safety in the Tesla Roadster. For example, cells used in the Tesla Roadster battery pack are
all packaged in steel cans. This feature offers multiple safety benefits. From a mechanical
standpoint, the steel case of each cell provides structural rigidity and strength. This helps
dissipate extreme mechanical loading as well as providing protection against objects penetrating
or compressing a cell and thereby shorting it.

Thats the sort of things you have to do if you want to sell to the public and avoid litigation.

 

[knoxie]

Hyena your post had me in stitches!

We all need to get some perspective here before you all go running for hills and selling all your batteries on Ebay, Keplers post has highlighted maybe 1 of 2 things here, a quality control issue with the battery or a harness wiring problem this video does not highlight Lipos inability to be a safe, cheap, light and powerful source of energy, both john in CR and Kepler had issues with brand new cells that had never been tested or used remember.

We all agree there are risks with all chemistries, A123 cells still cause fires, Lead acid causes fires, no chemistry is safe and because of this you have to treat them all with same level of suspicion then? again it boils down to a simple risk assessment, can my battery pack cause a large fire? the answer is yes no matter what the chemistry is so just take relevant precautions.

I wont keep or charge my pack in the house but then again I never did when I ran lead or Nimh either, fires with electric vehicles are as likely as fires with petrol ones IMHO and I am pretty sure we all avoid keeping petrol cans in our houses for this reason.

Kepler has the right approach and he was stood next to this when it happened, he has learned from it, took measures to mitigate the risks to himself and his home, he hasn't panicked or ripped out his pack and attached a trailer for his lead acid batteries?

The good thing about the forum is that we all learn from other peoples experiences, this is a good one because I think in general a lot of the builds concentrate far too much on how fast they go at the expense of safety, which is fine for the scientists out there like our Luke but not so good for the man in the street.

Like I said...follow the rules and nobody gets hurt

 

[flathill]

...The superiority of Tesla's small cell form factor approach from a safety standpoint will become more and more apparent...

Its not just the small form factor,..they have "cell level" safety features also ...

The cells used in the Tesla Roadster all have an internal positive temperature
coefficient (PTC) current limiting device. The primary role of this PTC is to limit short circuit
current on an individual cell level. It is important to note that this device is completely passive
and functions without any inputs from the rest of the battery pack systems.
A second level of protection is provided by the Current Interrupt Device (CID). Each battery cell
used in the Tesla Roadster has an internal CID. These devices serve to protect the cell from
excessive internal pressure. In such a case the CID will break and electrically disconnect the cell.
High internal pressure is generally caused by over-temperature or other failures that then result in
over-temperature.
The cells also incorporate numerous mechanical, thermal, and chemical factors that contribute to
their safety in the Tesla Roadster. For example, cells used in the Tesla Roadster battery pack are
all packaged in steel cans. This feature offers multiple safety benefits. From a mechanical
standpoint, the steel case of each cell provides structural rigidity and strength. This helps
dissipate extreme mechanical loading as well as providing protection against objects penetrating
or compressing a cell and thereby shorting it.

Thats the sort of things you have to do if you want to sell to the public and avoid litigation.

I think we are going to have to all take safety more seriously unless we want to end up like our friends in Norway...one EV conversion fire on a ferry resulted in a ban on all EV conversions.

Imagine you are big oil...hmm I own the media I think I'll start sensationalizing every EV fire in an effort to create a panic. I also don't want Joe Blow to buy a bolt-on super cheap EV conversion kit for his 69 Camaro that goes 300 miles with 300hp for $5000. I think I'll call my army of lobbyists to pass a law ban EV conversions. While I'm at it I better make a call to my CEO buddies in the insurance industry. Also need to call the NAREIT and have them change their policies. I just frocking around but the point is...burn shit up not down.

 

[bigmoose]

This is a good discussion for all of us! I have some familiarity with hazard controls, and we know that procedural "controls" are the worst. We "burn down" that risk during the design cycle every way we can by designing the controls into the hardware and making it "idiot proof." That is why no two connectors on an avionics box can be the same (someone, somewhere will cross connect the cables), why we use scoop proof connectors... etc. We are not always successful though and incidents happen. We pick up the pieces, redesign, and move on...

The risk that concerns me the most here is the QA (Quality Assurance) risk in the formulation and manufacture of the LiPo that we buy. We cannot "control" that. We can control how we assemble the battery, how we handle it, use it, charge it, etc. If there is a hidden criticality I defect in formulation that makes the electrolyte unstable, or the foils susceptible to shorting, we are at the mercy of the manufacturer. ... and a manufacturer to which we have no recourse. 1 in 1000 is not an acceptable risk for me for casual home use with my family around and at risk for the incident.

Contrary to popular beliefs, this is where the threat of litigation helps. It will result in product improvement (good ) or removal of the product from the market (bad )

These cells "going off" with no provocation is the risk that bothers me. Overcharged, hit with spot welder currents, then hit with a hammer (2 feet from the red gas can... ) I think we can control. It's the "poof" and my house and shop is gone, not to mention the risk to the kids sleeping upstairs...

BTW A123 has a great design standard for OEM's on what is required in their BMS and battery physical design to be approved to be sold OEM A123 cells. It is a good read. I am sure it is the result of potential litigation or past litigation we have not heard about. In this case, A123 has restricted who they will sell cells to directly (not us) and imposed restrictions on large corporate end users (Auto Industry) also. I would baseline my design today on A123 20AHr pouch cells, if I could get them easily and at a fair price.

 

[Ypedal]

My beef with the A123 cells we get on the hobby market is that they have to be purchased out the back door and not directly from QC certified A123 vendors, i've had plenty of questionable packs come thru my door ( not A123 packs.. ) but after repairing and disecting quite a few of them it's obvious that alot of the crap we get sold is recycled, repurposed, QC fail production line rejects.... whey did they fail ? nobody knows and nobody is saying.. and no usable cell goes to the trash in china..

" New.. Improved Formula " .. " Authentic " .. words used in these ebay adds.. makes my stomach churn...

I much prefer to get brand new production line cells from HK and do QC myself...

 

[auraslip]

Well said big moose.
I would be curious to read a123's OEM requirement check list. I bet it's fairly stringent.

As far as the risk of litigation - now that HK has warehouses in the US how long before some one like John or Kepler sue them to oblivion when they don't get incredibly lucky and their is a substantial loss of property and life?

It's gotta happen eventually.... and this will be very new and interesting legal grounds..... the day when the battery sales died....

I think we are going to have to all take safety more seriously unless we want to end up like our friends in Norway...one EV conversion fire on a ferry resulted in a ban on all EV conversions.

Imagine you are big oil...hmm I own the media I think I'll start sensationalizing every EV fire in an effort to create a panic. I also don't want Joe Blow to buy a bolt-on super cheap EV conversion kit for his 69 Camaro that goes 300 miles with 300hp for $5000. I think I'll call my army of lobbyists to pass a law ban EV conversions. While I'm at it I better make a call to my CEO buddies in the insurance industry. Also need to call the NAREIT and have them change their policies. I just frocking around but the point is...burn shit up not down.

 

[John in CR]

I much prefer to get brand new production line cells from HK and do QC myself...

That sounds like a reasonable approach for me as well, especially since it's really the only source of bargain prices combined with high energy and power density. So far in the thread the QC is still a bit vague and incomplete.

I'd like to put my lipo packs thru some hard testing to prove that they're not defective, so I can be at ease putting them on a bike. I'm lucky that I park my bikes were a house fire isn't a concern, so my risks are only of time and money...but I still want to avoid failures. I like to ride, not tinker or troubleshoot.

 

[knoxie]

I much prefer to get brand new production line cells from HK and do QC myself...

That sounds like a reasonable approach for me as well, especially since it's really the only source of bargain prices combined with high energy and power density. So far in the thread the QC is still a bit vague and incomplete.

I'd like to put my lipo packs thru some hard testing to prove that they're not defective, so I can be at ease putting them on a bike. I'm lucky that I park my bikes were a house fire isn't a concern, so my risks are only of time and money...but I still want to avoid failures. I like to ride, not tinker or troubleshoot.

My feelings exactly John and this is one of the reasons I never recommend them to the newbs, I check the cells before I use them, I also dont like to have to keep tinkering as well I prefer to ride however I do keep an eye on them though, QC of stuff from the PRC has always been an issue, you should have seen some of the kit we were getting years ago from the PRC, they are getting better though.

The HK Lipo I have had has been so much better than anything that I have had in the last 5 years, the amount of low grade lipo about is scary though and the amount that is shipped in cheap toys and the like and its all over the place we would be hearing of so many problems the world round if this stuff was self combusting all over the place, the common factor in the 2 incidents so far has been the supplier though so it does pay to be vigilant.

The more of us that use the packs the more incidents may arise time will tell, like you said the only risks are time and money this is the same for me too, there isnt anything life threatening about that for me anyways.

 

[auraslip]

Found this foam. It's resistance decreases when compressed. http://www.inventables.com/technologies/conductive-foam-sensor

Might be able to make a pressure sensor to detect puffers with it.

 

[Kepler]

We have some good discussion happening here and some good rational suggestions in relation to mitigating the risk. Something I would like add to my LiPo safety check list is a good method of testing a pack before using it on a ebike. A balance charge and voltage check is a obvious start but what is more important I think is a discharge cycle under a decent load that can be carried out safely.

I would be keen to hear how people are achieving this sort of test without actually riding the bike.

As a side note, I carried out further investigation on the failure at my friend's shop. Checked the series wiring loom and found all this to be in perfect condition. A new set of packs were installed (but kept in a liPo charging bag) and connected to one of my spare controllers. Still had som issues with Phase wires and needed a few combo tries to get the bike going. We monitored current and wire temp constantly when doing the testing and loads were found to be very low. Got the combo right after 3 tries and gave the bike a good test run. Packs we fine and balance was consistant. So far so good but we still dont trust these Zippies and will be replacing them with Turnigys before any serious riding is done.

 

[neptronix]

Well, you can use a charging/discharging charger such as the hyperion or iCharger line to do a test.
I used 6x 12v 50w halogen lights ( 3s2p ) to discharge my 5ah 10S packs at a rate of 8-9amps which took about 30 minutes per pack, and charted the voltage of each cell using the monitor mode of my iCharger 1010b+, using the included logview software.

By doing this i found 1 runt pack and 9 good ones.

Discharge after initial balancing cycle:

Charge after discharge to ~3.3v/cell average:

By doing this test, i found one pack that had 2 weak cells in it which would have became a problem down the line:

BTW it was a turnigy that puffed on me with 0 cycles on it. If i put voltage into it, i bet i would have had the same results as your zippy pack.

So i think the lesson we learned in John in CR's lipo fire and your fire is, never trust a lipo pack until you've tested it. If there's going to be a fire venting due to a cell defect, it should happen within the first cycle.

 

[heathyoung]

Found this foam. It's resistance decreases when compressed. http://www.inventables.com/technologies/conductive-foam-sensor

Might be able to make a pressure sensor to detect puffers with it.

Meh - anti-static foam (like what IC's are packed in) does exactly the same thing. So does a security pressure matt.

 

[RVD]

Well, you can use a charging/discharging charger such as the hyperion or iCharger line to do a test.
I used 6x 12v 50w halogen lights ( 3s2p ) to discharge my 5ah 10S packs at a rate of 8-9amps which took about 30 minutes per pack, and charted the voltage of each cell using the monitor mode of my iCharger 1010b+, using the included logview software.

How would you recommend a test without using logview?

Cells are usually around 3.8 when shipped so how about if we charge up to 4.1 and check balance taps, then discharge with the charger (e.g. hyperion) down to 3.5 and check balance taps, then charge back up to 4.1 and check balance taps and if it seems good, maybe it's all good? Would a weak cell pop up in a non-balance charge (we'd see 1 or more cells off from the others by a lot (more than .3v)) after a charge?