A question for Paul DOve, Whence came your evidence of self discharging in Li ion cells?
I have the other impression entirely - that there is no mechanism by which self discharge is even possible. If cells are mismatched in a pack there can be an accumulation of drift relative to other cells in a pack (which can cause problems), parallele cells will equilibrate among themselves (why you want them to be closely matched) BMS and other electrical/electronic equipment can produce a parasitic load across a pack, but a charged cell sitting alone on a shelf does not lose charge. It's capacity can decrease so that subsequent performance is less good, but there is no self discharge. Mike On Thu, Jun 18, 2015 at 10:59 PM, Cor van de Water via EV <ev@lists.evdl.org > wrote: > Paul, > > I presume you never ride in a car, because Ford's Pinto was a bomb on > wheels and unsafe at any speed. > > Your line of reasoning does not warrant a serious response and I have > given many reasons why a BMS > is a good thing - I like to discuss based on arguments and data, not on > lore and incidents. > > BTW, last I heard the root cause of the dreamliner fires is still unknown, > there is suspicion > about the quality of the batteries, similar to what caused laptop > batteries to catch fire > due to impurities embedded in the cells and trigger thermal runaway. > I have helped to investigate a fire in a converted EV with Lithium-Ion > prismatic cells > that I suspect (but it was never conclusively proven) was caused by > manufacturing defects. > There was no BMS on that pack and it was not being charged, still it > caught fire just sitting. > One thing that I found was that what appeared to be a hotspot also showed > severely deformed > (folded crooked as if they were rammed into the prismatic case) cell > plates (the original > pouches that are contained in a bundle inside the prismatic cell) in one > of the cells. > But you can't say "they used a BMS so that caused the fire". If you have a > source > that proves that it was in fact the BMS causing the fire then I would be > interested in a link. > Here is what I have: > > http://arstechnica.com/business/2013/02/investigation-reveals-cause-of-battery-fire-on-boeing-787-dreamliner/ > https://en.wikipedia.org/wiki/Boeing_787_Dreamliner_battery_problems > > http://www.ifsecglobal.com/dreamliner-lithium-battery-fire-cause-still-unknown/ > > Regards, > > Cor van de Water > Chief Scientist > Proxim Wireless > > office +1 408 383 7626 Skype: cor_van_de_water > XoIP +31 87 784 1130 private: cvandewater.info > www.proxim.com > > > This email message (including any attachments) contains confidential and > proprietary information of Proxim Wireless Corporation. If you received > this message in error, please delete it and notify the sender. Any > unauthorized use, disclosure, distribution, or copying of any part of this > message is prohibited. > > > -----Original Message----- > From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Paul Dove via EV > Sent: Thursday, June 18, 2015 6:31 PM > To: EVDL Administrator; Electric Vehicle Discussion List > Subject: Re: [EVDL] Bicycle battery > > Even Boeing burned up dream liners with a BMS. > > Got any other argument besides everyone is doing it? > > > > Sent from my iPad > > > On Jun 18, 2015, at 2:02 PM, EVDL Administrator via EV < > ev@lists.evdl.org> wrote: > > > >> On 18 Jun 2015 at 11:43, Cor van de Water via EV wrote: > >> > >> That pack is very nicely top-balanced and I expect that many more > >> BMSs that you are not even aware of in daily appliances such as power > >> tools will all top-balance. > > > > One more time. There is a really good reason that the only place you > > find aversion to BMSes is among EV hobbyists. > > > > Real world electronics manufacturers -- the ones who build millions of > > laptops, mobile phones, power tools and yes, commercial EVs -- know > > that you don't sell a product with a lithium battery unless it has > > ample smarts to protect the battery, the user, and the manufacturer. > > > > Trust me, these guys have bean counters looking over their shoulders. > > They wouldn't be using BMSes if they weren't necessary. BMSes protect > > the battery from early failure, the user from hazard to life and limb, > > and the manufacturer from the lawyers! > > > > 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 > > For EV drag racing discussion, please use 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 > For EV drag racing discussion, please use 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 > For EV drag racing discussion, please use NEDRA ( > http://groups.yahoo.com/group/NEDRA) > > -- To invent, you need a good imagination and a pile of junk. Thomas A. Edison <http://www.brainyquote.com/quotes/quotes/t/thomasaed125362.html> A public-opinion poll is no substitute for thought. *Warren Buffet* Michael E. Ross (919) 585-6737 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell michael.e.r...@gmail.com <michael.e.r...@gmail.com> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150618/d4c725e6/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
