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My Project Lithium Battery Caught Fire

Discussion in 'Gen 2 Prius Main Forum' started by sworzeh, Mar 12, 2024.

  1. T1 Terry

    T1 Terry Active Member

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    Didn't mean to sound like I was exiting the thread, just explaining why the replies are bit all over the shop without a lot of direct references made.
    I believe this thread is about an LFP battery that caught fire. It wasn't punctured, so the staking is not particularly relevant, yet the fact that additional holes to allow air to enter so oxygen was introduced into the cell was required to get one of the test cells to actually catch fire.

    The suggestion hydrogen was a gas in the vented electrolyte vapour, yet the testing was only carried out on burning electrolyte vapour, leaves many unanswered questions. Using that flawed methodology to assume hydrogen is 50% plus of the ejected vapour just muddies the water, more valid testing would be required.
    The possibility that the hydrogen was not actually part of the vented electrolyte vapour but rather part of the by product of something within the vapour burning in a restricted oxygen supplied combustion situation causing an incomplete combustion, needs to be answered one way or the other .... one paper started with "Theoretically" regarding the hydrogen content .... we all know the difference between theory and the real world, in theory they are the same, in reality, they are often not even close .....

    Hopefully once I get home and the dust settles, I'll have more time to do research regarding back up testing by the likes of Carnegie Mellon (sorry about my mutilation of the name) NASA etc, they had a lot of research work they conducted 12yrs or more back when I first became involved with LFP cells and their various construction designs and why that design was chosen. Paint me sceptical, but I don't trust any of the specs or testing from Chinese "research" facilities, very few of them have panned out to match my test results and when questioned, a whole different set of parameters were used to obtain the results they advertised ..... Winston was one of the exceptions, as was A123, but they only sold to major manufacturing concerns.

    The 18650 for example is two long sheets sprayed on both sides with the active on one sheet and the graphite on the other. Designed for high C rates, not longevity or the storage and release over longer periods at a lower C rating. Prismatic, the type I prefer because of the multiple layers spreading the variations out that are inherent in mass production, a spring loaded vent, insulated case and capable of being compressed to minimise case bulging ..... the pouch cells came later and to be honest, not a fan, too many failures and poor heat dissipation potential. I'm intrigued by the new cylindrical cell sizes as to why? I'm guessing to house the increased capacity and possibly integrating the multiple layers found in prismatic cells with the long contact facing available in a cylindrical cell.

    I am interested in your ideas regarding other reasons a cell would heat up, if the cell is cold enough to freeze the electrolyte, the wrong compound electrolyte was chosen and probably the wrong combination of elements in the active material. This is what directed me to the Winston LYP chemistry, all the benefits of LFP with an added minimum threshold of -36*C and upper threshold of 70*C .... I like the sodium ion cells I'm part way through testing because they stretch this a bit further with better under voltage and over voltage tolerances before they cease to function as specified ... actually, I'm still in the process or discovering if they meet the manufacturers specifications or just what specs they really have in regards to their expected performance.

    I'm not really interested in supporting or rejecting anyone's claims against how someone else went about their BMS design, either it worked or it didn't. Did it catch fire? No evidence has been forthcoming that there was actual combustion involved. If the electrolyte vapour had been vented outside the vehicle cabin, would this circus have even got the tent up?
    I know for certain the NiMh modules catch fire if over voltage charged, the insurance investigator backed that up, the melted modules and blacked steel cases just confirm there was combustion ... the flames licking out of the vent by the back passenger door was enough to convince me it was on fire :lol:

    T1 Terry
     
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  2. mudder

    mudder Member

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    Sorry I didn't reply sooner... I got really sick last week... seems like a combination of covid and allergies, although I tested negative.

    Please review the previous posts. One test (the one that yields 50%) was performed in a noble gas, hence there was no chemical reaction due to flame, unless that flame was oxidized by chemicals within the cell (unlikely for LiFePO4)).

    I'm always down to read quality sources.

    Yeah, A123 initially only sold to those that would allow A123 to review their designs. They didn't want some rando to tarnish their name by designing and selling dangerous products. Even the KillaCycle guy got a slap on the wrist after he crashed his A123-equipped bike into a parked truck. At the time A123 was the only game in town for high charge/discharge lithium, so you basically had to play by their rules. I'm still amazed they managed to go bankrupt.

    Related: I still have an A123 cell on my long term tester that hasn't failed yet.

    In general there are three broad categories:
    -Overcharging (chemical breakdown)
    -charging too fast (electrical resistance)
    -failure to account for cell aging (NexPower packs lack any method to control this)

    Interesting stance.
    I would counter (again) that selling an LFP product without a BMS is a recipe for disaster.
    I would counter that in at least five cases (that I know about), it "didn't work"... the pack experienced a thermal event.
    I would also counter that the customer shouldn't expect their product is going to have a thermal event. Doesn't matter if that is fire, smoke, or just a thermite meltdown... the pack should have the requisite parts to prevent it from disassembling itself in a gooey form under the rear seats. No customer wants that, and well designed products have measures to prevent this from occurring.

    I agree this happens, albeit infrequently.
    Note that NiMH voltage dips slightly as each cell hits full, which the OEM computer can detect. This allows the OEM computer to determine when a cell is full. It's not perfect, but it's something. Note that this chemical property of NiMH cells is measurable even with multiple cells in series between BMS leads, whereas lithiums gradual (and then faster) cell rise is much harder to detect without per-cell BMS leads).
     
  3. black_jmyntrn

    black_jmyntrn Senior Member

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    I like how you embraced the honda boy. :: wink ::
     
  4. T1 Terry

    T1 Terry Active Member

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    In each of these instances, cell voltage rise or drop below the stable voltage limits precedes temperature rise .... stop the charging or load when the voltage goes outside these ranges and the thermal run away never occurs, negating the need for thermal measurement per cell.
    Once more than a single cell in series is involved in the voltage measurement, it becomes a bit trickier to stay within the stable voltage range for each cell in the series group, the more in the group, the closer to impossible voltage alone can avoid a thermal event in any cell within the group.

    T1 Terry
     
  5. T1 Terry

    T1 Terry Active Member

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    Unfortunately for my wife and I, a day after we returned home to attend doctors appointments, both our house and motorhome burnt to the ground. From what I can tell, the power companies electrical meters in the power box or something within this metal box, started the fire. It burnt the corrugated iron garage it was attached to, the motorhome was parked between the garage on the house, so it caught fire and carried it over to the house.
    We were at the doctors some 40kms away when the neighbour rang to tell us the whole lot was on fire, by the time we reached, there it was a matter of watching everything go up in flames .... we had what we were wearing and the Prius we were travelling and Coco the dog, and that was it. Our business workshop burnt down 15 mths ago, nearly to the day, between them, everything we had is now gone ..... had to go to a late night supermarket to buy jocks and socks and the next day, buy a computer because we both lost ours and all the back up hard drives .... we had stored one in the house and one in the motorhome for redundancy ...... the wife is ex IT, so has zero faith in the cloud keeping anything secure, very recent events have confirmed her doubts it seems ......

    So, unfortunately, there will be no results from tests on the different Na ion cells (15Ah cylindrical and 200Ah prismatic) because they appear to have been destroyed in the fire as well ...... still can't get in the place until the forensic investigators for the house insurance and motor home insurance companies have been and recorded their findings ......

    T1 Terry
     
  6. T1 Terry

    T1 Terry Active Member

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    As the title refers to a battery catching fire that would require some sort of intervention to stop the vehicle being engulfed in flames and destroyed, it clearly didn't happen, did it?
    An actual fire would be a serious issue, a cell venting is more of an inconvenience issue, a serious one, but at no stage life threatening.
    On those grounds, it falls back to "buyer beware" and in reality, the LFP is a far safer chemical formula than any that contain cobalt, that would have resulted in fire without a doubt under the same conditions.
    I still dispute the hydrogen being part of an LFP electrolyte vapour release .... if you have ever witnessed a fire where hydrogen was in the gas mix, the heat and intensity of the rapid fire front is very close to an explosion and very little partly burnt vapours or gasses remain in the smoke cloud ..... not a "smoke cloud" but rather a fireball .....

    T1 Terry
     
  7. ChapmanF

    ChapmanF Senior Member

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    I'm very sorry for your loss, glad you and your wife and Coco are ok.

    Something very similar happened to my parents years ago. The insurance company sent 'round a forensic electrical guy who hacksawed out the meter box and tossed it in the trunk of his car and drove off. My parents assumed for some time that they might eventually hear something from him about the cause, but he never seemed to make any report to anyone but the insurance company that sent and paid him.

    The forensic guy happened to be the dad of someone I knew through contra dancing, but that didn't give me any extra leverage to learn what happened.
     
  8. T1 Terry

    T1 Terry Active Member

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    Interesting, we had the fire and police fire investigators visit the site when the last of the fire was being extinguished. They seemed to avoid looking at anything that might point to a govt body fault and rather attempted to twist the finding to point to the fire starting in the motorhome ..... even though it was obvious from the damage pattern, the prevailing wind direction and the fact the meter box was laying on the ground completely burnt out, just where the fire started.
    It will be interesting to hear what the two different insurance company forensic people find, they will be desperate to blame someone other than their insurer for the fire. My guess, and only a guess on my part, the electrical people accept the blame and pay up, with the condition being a total non disclosure ...... the last thing they would want is an investigation or scare campaign to start and all power boxes requiring a safety audit ........ The power company recently installed new meters that both report to the electrical supplier to eliminate the need for a meter reader, and change the power charging to time of use rather than a flat rate ........

    T1 Terry