The video does not specify what went wrong to cause the first cell(s) into thermal runaway and catch on fire. The Tesla Li cells may potentially do that if (internally) shorted due to manufacturing defect or failure to maintain them within required voltage range. The cells may have been charged before placing them into the vehicle, especially if the pack was low beforehand it is tempting to put a charge on them for fear of them going dead, or the pack module may have rested on some metal parts (rear diff or frame support) that touched the pack in more than one place and shorted it. I hope Rich will post another update on the car to tell the whole story. It is easy for a dead pack (which has high internal resistance) to share charging voltage unevenly, causing some cells to get excessive voltage due to those cells being the *lowest* in Soc, highest in resistance and thus get the most charge voltage. The other thing of cause is that the pack may have discharged to the point that some cells were at zero (or even reversed, which is even more damaging) while still in the dead Tesla and then charged without BMS before being placed in the car. But that is all speculation right now. Fact is that at least 1 cell had a thermal runaway, started spitting fire and eventually the entirely of the two modules burned in a spectacular fireworks spitting burning cells in all directions… Cor.
Sent from Mail for Windows 10 From: Matthew Quitter via EV Sent: Tuesday, December 4, 2018 9:40 AM To: Electric Vehicle Discussion List Cc: Matthew Quitter Subject: Re: [EVDL] Tesla battery cells (no BMS) burst into flame... I still don’t know what actually caused the fault. From what I watched on the video and previous ones on that project they’re still in the preliminary planning stages. It appears the pack was not connected to anything, just placed in the car. Is that correct? Which would suggest it spontaneously failed - something I’ve never heard of and tell customers never happens. Worrying as I have 10 Tesla Model S modules sitting waiting to go into a couple projects! Perhaps there was a defect in the module? Or it was removed from its plastic casing and rested against something conductive?! I would like to know what actually caused the initial failure before thermal runaway. Matthew London Electric Cars > On 4 Dec 2018, at 17:15, EVDL Administrator via EV <ev@lists.evdl.org> wrote: > > Not that I want to start an argument, but IMO those folks who say "I don't > need no stinkin' BMS!" should be required to watch the hot action part of > that video clip at least once -- just so they give it a little more thought. > > The "live ammo" question from the firefighters is telling. It DID look and > sound like that. There's a spectacular amount of energy in those little > lithium cells, and it can do unsettling things when it's released all at > once. > > David Roden - Akron, Ohio, USA > EVDL Administrator > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > EVDL Information: http://www.evdl.org/help/ > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > Note: mail sent to "evpost" and "etpost" addresses will not > reach me. To send a private message, please obtain my > email address from the webpage http://www.evdl.org/help/ . > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) > _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA) -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20181204/2578e227/attachment.html> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
