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My Project Lithium Battery Caught Fire

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

  1. Xeico

    Xeico New Member

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    #121 Xeico, Apr 1, 2024
    Last edited: Apr 1, 2024
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  2. Xeico

    Xeico New Member

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    1) In hybrid batteries that use lithium-ion cells, Toyota has balancing.
    2) Tesla is an electric car, the battery mode is completely different. Hybrids (HEV) almost never (with rare exceptions) are charged to 100%
    3) You are wrong

    I guess the problem is not the cell chemistry, but the fact that he uses cheap cells that are not matched to the same capacity. This leads to overcharging of some modules and undercharging of others.
    The root cause is low-quality (NOT automotive grade) cells.
     
    #122 Xeico, Apr 1, 2024
    Last edited: Apr 1, 2024
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  3. mudder

    mudder Junior Member

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    Today I finally got around to reproducing the failure mode @sworzeh reported in post#1. @sworzeh was spot on with their "smells like Sharpie" statement... when these cells vent, their electrolyte reeks like a river of industrial strength uncapped sharpies stuffed down your nose!

    ...

    I was unable to reproduce the failure on my first attempt, which was as follows:
    -First, I charged a cell at 170 amps until it hit 3.65 volts, and then;
    -I maintained 3.65 volts until the charge current dropped to 30 amps, and then;
    -I then immediately switched to discharging into a 20 mOhm load, which is ~183 amps @ 3.65 volts, and ~140 amps @ 2.80 volts.
    -Once the cell dropped to 2.80 volts, I immediately repeated the charge cycle.
    -In total, I repeated this test four times back-to-back.

    Results:
    -The cell did not vent.
    -The pack enclosure melted, but did not burn.
    -The external module temperature was 80 degC when the test finished. It's likely the internal temperature was much higher.
    Note: these test currents likely exceed NexCell's specifications
    ...

    After this first test, I immediately switched to a neighboring cell and began test two:
    -First, I charged a cell at 100 amps until it hit 3.65 volts, and then;
    -I maintained 3.65 volts until the charge current dropped to 30 amps, and then;
    -I then immediately switched to discharging into a 20 mOhm load, which is ~183 amps @ 3.65 volts, and ~140 amps @ 2.80 volts.
    -Once the cell dropped to 2.80 volts, I charged the cell at 100 amps without a voltage limit, and then;
    -When the cell hit 3.90 volts (3.65 volts is maximum 'safe voltage' for LiFePO4), the cell forcefully vented (enough to rapidly move a 40 pound concrete block resting on top of it). The vented electrolyte condensed on the surrounding concrete surfaces.

    Results:
    -The cell vented when overcharged. Note that the V1 NexCell circuit board is unable to alert the OEM BMS that a particular cell is overcharged, hence the V1 hardware cannot limit regen when a cell is overcharged.
    -A thermal event did not occur.
    -The cell under test did not appreciably expand.
    -The cell under test was just over 115 degC, as measured by a thermal imager.
    -Following this test, the cell was discharged to 0.0 volts and the terminals are now shorted to remove all residual energy.

    ...

    Based on my results from the first two tests, I suspect that to reproduce @sworzeh's thermal event, the cell needs to get really hot prior to overcharging. This allows enough energy to accumulate inside the modules, such that they melt - rather than burn - until the cell vents due to internal pressure build up.

    Note that since I was only testing QTY1 cell - and not the entire pack - I was only sinking a few hundred watts into a single cell... the neighboring cells were neither charged nor discharged. In the case where the entire pack is charging/discharging, there will be more heat build up for a given charge/discharge current.

    ...

    Overall findings:
    -overcharged NexCell cells vent without burning. This is expected due to LiFePO4 chemistry.
    -overheated NexCell cells melt without burning.
    -it's likely that some combination of both overcharging and overheating could cause a thermal event to occur.
     
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  4. TMR-JWAP

    TMR-JWAP Senior Member

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    Fortunately, I don't think there is such a thing. I'm pretty sure Toyota has the numbering system where there isn't a P and C (for example) with the same 4 follow-on digits, just like no DTCs have the same numbers for subcodes. With C1241 being a real code, there will be no P1241. If the C1241 has a 344 subcode available (just an example), no other DTC will have that subcode as a possibility.
     
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  5. ChapmanF

    ChapmanF Senior Member

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    I'm not sure I would assume too much about Toyota's deliberate commitment to the pattern you've seen.

    For starters, they're not in control of all the code assignments. All U0, B0, C0, P0, and P2 codes are standardized by SAE, and those guys aren't doing anything fancier than assigning numbers in each range in order. There's no reason, say, a chassis code C051A (left rear wheel speed sensor - mechanical), and a powertrain code P051A (crankcase pressure sensor circuit), a network code U051A (invalid data received from door switch E) can't all exist.

    You don't see these particular codes in a Prius because it hasn't got a mechanical left wheel sensor, or a crankcase pressure sensor, or a communicating door switch E. But if it had any of those things, Toyota would use the SAE code for it, rather than making up codes of their own in the manufacturer-defined ranges. In fact, they have changed manufacturer-defined codes they used in earlier Prius generations to be the SAE standard codes for the same things, in later generations after SAE standardized codes for them. The rarity of such overlaps between Prius codes probably comes down a lot more to coincidence than to design.

    As for the INF codes, a lot of that may come down to history too. For example, in gen 1, there weren't many SAE standard codes for hybrid vehicle inverter issues, and Toyota made up the manufacturer-defined code P3125 to cover pretty much anything that could go wrong with an inverter, using a whole slew of different INF codes.

    In later generations, after SAE defined a whole bunch of P0 codes covering different inverter problems, Toyota moved to using those instead, so now all the different things that can go wrong don't all have the same DTC with different INF codes—they're now parceled out into many different SAE standard DTCs—and they also still have the INF codes they had in the earlier generation. So it happens that the INF codes don't overlap, among all the various standard DTCs that all used to be P3125 with different INF codes. There are plenty of other examples where that happened.

    That history tends to explain why it looks like INF codes are non-overlapping between DTCs, but as to whether Toyota ever sat down on purpose and said "we're never going to have overlapping INF codes between DTCs," I wouldn't count on it.

    [​IMG]
     
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  6. marhuu

    marhuu Junior Member

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    RIP Nexcell Lithium battery. Quality system is required for every industry as we saw how it changed Japanese industry in 1960's
     
  7. mr_guy_mann

    mr_guy_mann Senior Member

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    Excellent write up.

    While I understand the codes are used for demonstration purposes only, (and are noted as not being actual Prius codes), you still were "gotcha-ed" by the code description fortune cookie.

    A "wheel speed sensor - mechanical" code would indicate that the ecu detected a problem with the signal that's caused by a mechanical fault (such as a damaged tone ring). It's not a circuit fault.



    Posted via the PriusChat mobile app.
     
  8. sworzeh

    sworzeh New Member

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    The car is a "single family" owned car bought new by my family in 2007 that was given to me in my parent's divorce in 2012. It's the only car I've ever owned. My father is a skilled, self-taught mechanic and did all the work on it himself until I moved away for surgery fellowship across the country, which is why all my potato questions are popping up now. The car is getting old and I'm not very skilled at solving problems. I can, however, fix anything with step-by-step instructions. Mostly I just lurk if a problem arises, and I can find someone who had the exact same problem and fix it. I've fixed some easier things myself over the years without posting about them, such as the AC compressor, 12V battery changes, Lithium battery installations, etc. But for the harder things I ask for help.

    The Nexcell I bought and installed myself because I was hoping to get better mpg and I wanted something reliable. My car was at 325k ~2 years ago when I installed it and I was worried it wouldn't make it across the country to move for surgery fellowship. I was researching new hybrid packs and I hated the idea of refurbed packs, so I stumbled across Project Lithium with its promise of improved MPG. I reasoned with myself that if I could get 10mpg more, it would pay for itself. So I gave my old packs to my dad to revive his dead Prius, and I installed the Lithium pack. The rest is history as seen in this thread.

    As far as my typos go, I made that post around midnight when I wake up at 0600 as a surgery resident. I had been up working on my car nightly and researching all I could and not getting much sleep in between working 80 hours a week. I'm sorry, I mixed up the P and the C because Dr. Prius gives me P codes and Techstream gives me C codes. I fixed it after it was pointed out that it was incorrect. It doesn't mean that I installed my battery incorrectly. My car did drive with this battery for a few weeks before catching on fire.
     
  9. sworzeh

    sworzeh New Member

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    Very interesting! Thanks for testing these cells. It's actually rather calming to hear that these cells are different from the explosive lithium fires seen in Teslas. The fire department did seem incredibly nervous when I told them I installed a lithium battery in the car, and they insisted on staying until it stopped smoking.

    To give some more background of the conditions in which my melt/fire occurred: My cells now are largely only used for 15min, 5mi commutes, but I'm in the mountains and it's straight uphill or downhill with lots of stoplights. Ever since I put in my V2+2.5 my car acted confused on what it was supposed to be doing with the hybrid battery. I'd stop at a stoplight, my hybrid battery would show as 100% full, then my car ICE would rev up and charge it more. This would sometimes last the whole duration of the stoplight. I'm told this isn't abnormal, but I haven't noticed it at all with the OEM hybrid pack that I just installed. I don't remember the V1 doing this, but the V2 definitely did. It was as if the Prius didn't know that it was already fully charged so it was trying to charge it more. Like it was out of sync. The day my cells melted, it was around 50 degrees and I was on my "downhill" from the mountain commute, so perhaps it was charging even more than usual. I didn't look at it or notice anything abnormal. I was around 1-2mins from home when I first smelled Sharpies, but I looked back any nothing looked abnormal in the back of my car. Plus we have a horrible pollution problem in the mountains. Then it became overwhelming even with the windows open, so I looked back and the car was filled with smoke. As seen in the pictures, it was mostly the special blade that melted. But the two cells right next to it are also cracked/warped and are fused to the special blade. The rest of the cells look fine. The car was still driving fine with no warning lights even with the melted/smoking battery.

    In the aftermath, I cleaned my car with my wife for 5.5 hours, scrubbed everything, removed the hybrid battery duct work and cleaned it, removed the seats, scrubbed the ceiling. Everything. It still smelled disgusting and I couldn't drive with the windows down. I bought a commercial-grade ozone generator from amazon and ran it for their recommended amount of 3mins. Still smelled awful. Then I ran it for 30 mins total in increments of 5min to finally get rid of almost all the smell. Also ran a "new car" fogger. Now I just smell the faint Lithium/sharpie smell near the hybrid air vent but overall I'd say we're back to normal now. Other than that I made a post that my car was throwing C1241 and C1300 codes a couple weeks later, so I replaced the skid control ECU and the 12V battery and those resolved.
     
    #129 sworzeh, Apr 8, 2024
    Last edited: Apr 8, 2024
  10. black_jmyntrn

    black_jmyntrn Senior Member

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    FWW, I never thought it was skills or installer tissue. I'm say its could be based on age of car and something like one harness terminal with just the right amount of no seeum corrosion versus the alternative on the battery/soother related. that's just IMO I also know nothing to save two lives about batteries, maybe one tho for sure.
     
  11. Xeico

    Xeico New Member

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    Did you used signal shooter?
     
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  12. pasadena_commut

    pasadena_commut Senior Member

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    Is the car really that pink/magenta color as shown in the picture? If so, how did that happen?
     
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  13. TMR-JWAP

    TMR-JWAP Senior Member

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    For other than the OP, this may be the best question of the entire thread!!
     
  14. Plaman

    Plaman Member

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    I haven't seen much discussion about the install details of this particular pack:

    What was the install / assembly process that was used to install this particular pack?

    Did you reuse existing bus bars?
    How corroded were they / what cleaning process was followed to remove corrosion?

    Torque spec for the bus bar nuts?
    New or existing bus bar nuts?

    There are a few other nuts in the battery assembly that are considered "one time use" by Toyota. Were any of these replaced / properly torqued?

    Photo of the Battery ECU terminals, were they corroded?

    Torque spec for the bolts that screw into the bottom of each blade? (I believe these help ground the individual blades?)

    Was the pack as a whole properly torqued with the 5 final bolts into the chassis of the car? Clean and free of debris for a clean grounding connection?

    What was the climate where this pack operated? Was it climate control garaged or stored outside?
     
  15. TMR-JWAP

    TMR-JWAP Senior Member

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    Torque spec for the bolts that screw into the bottom of each blade? (I believe these help ground the individual blades?

    The bolts that fasten the individual modules to the battery case (bottom) are M5x0.8, the same as the module (+) and (-) studs. Torque spec is 48 inch-pounds. They DO NOT ground the module to the case, at least not intentionally. The steel insert on the module is knurled on the outer surface and pressed into the plastic module body. Sometimes, over the period of use, small cracks may form in the plastic, allowing electrolyte to make contact with the insert and sometimes leaking out around the "pressed in" insert. This is a frequent cause of a P0AA6 code, because it effectively allows the electrolyte to make electrical continuity with the battery case, which is in electrical continuity with the car body. You can see this very often as brown stains on the case floor under the ends of the modules
     
  16. Plaman

    Plaman Member

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    Your response was so informative, thank you for that.

    Is the P0AA6 issue unique to the project lithium blades or also the factory design?
     
  17. ChapmanF

    ChapmanF Senior Member

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    The P0AA6 code is provided to give an alert to any failure of isolation of the high voltage system, anywhere in the car. If there is any way for high voltage to find a conductive path to the car body or any other wiring in the car, P0AA6 will be shown. The car is checking for that all the time. There are also a few different INF codes to go with P0AA6 that help narrow the search down to a smaller part of the high-voltage system.

    [​IMG]

    Battery modules developing cracks and oozing some electrolyte has always been one way that a P0AA6 code can crop up (with INF code 612), even with factory modules. But the code will be given for a high-voltage "leak" for any reason anywhere in the car.
     
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  18. sworzeh

    sworzeh New Member

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    1. Followed Jack's youtube video

    2. Busbars were re-used. I soaked them overnight in vinegar per the instructions by Jack then sanded them down with sandpaper. No visible corrosion afterwards and I only picked the cleanest ones to use.

    3. 4 Ft lbs with a torque wrench

    4. Existing bus bar nuts, cleaned in the same manner as the bus bars

    5. If there are parts that are "one time use," none of that was made apparent to me when I bought this battery from Project Lithium. All my cables had very minimal to no corrosion after cleaning

    6. I don't have a photo and I'm not taking apart the car to take one, but envision very mild corrosion/blue discoloration on only a single terminal of the hybrid battery ECU that I cleaned/scrubbed prior to installing the lithium battery. None was on the cable.

    7. 4 Ft lbs with a torque wrench

    8. Didn't torque the hybrid battery into the car, no, I used an impact drill on low setting much like Jack did in his videos. Everything was meticulously cleaned though.

    9. Climate is mountains, pretty cold/snowy winters. It was stored in a covered garage that is not climate controlled (who can afford that lol... we drive 20 year old cars!)
     
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  19. sworzeh

    sworzeh New Member

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    I got the car in my parents divorce and wanted it pink. Cost was $1500 back in 2013 to paint it pink and use bondo to get all the dents out. My neighbor did it for me.
     
  20. pasadena_commut

    pasadena_commut Senior Member

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    That's one I have not heard of before. More than two cars and the excess went to the kids? When my parents split all I got was a move across town and a transfer to a different school district.