I think it is very valuable knowing that a Li ion cell can hold its charge indefinitely. Particularly compared to the incumbent competitor - lead acid cells. There is a least an implication that the the loses may be of no consequence after design and manufacturing improvements. There is no possibility of achieving this ever with lead acid.
On Fri, Jun 19, 2015 at 8:11 PM, Cor van de Water via EV <[email protected]> wrote: > David, > > Why do all manufacturers of Li-Ion batteries specify the amount of > self-discharge > and why do people like me who monitor Li-Ion batteries over time, see and > measure > the self-discharge? > I understand that you say "theoretical" the pure Li-Ion cell may not have a > self discharge mechanism and thus the actual present self-discharge > appears to be > a spurious effect, possibly caused by contamination, so the amount of > self-discharge > is a quality indicator of the (lack of) contamination in the cell... > > However, saying that the ideal (theoretical) cell does not have any > self-discharge is as valuable > as saying that the ideal (theoretical) connection does not have any > resistance. > In practice however you better take that resistance into account when > sizing your wiring and connections. > Similar to taking self-discharge (and especially the difference in > self-discharge between cells) into account > when designing a battery pack. > > 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:[email protected]] On Behalf Of David Nelson via > EV > Sent: Friday, June 19, 2015 4:37 PM > To: Bill Dube; Electric Vehicle Discussion List > Subject: Re: [EVDL] "Zero self-discharge" (was: Bicycle battery) > > Bill, > > I have dug through many scientific papers on Li batteries and how they > work and I haven't been able to find anything about a theoretical > self-discharge mechanism. I have found some explicitly talking about the > lack of a charge shuttle mechanism like in lead-acid batteries, however. > > One paper I read has a section devoted to figuring out a charge shuttle > mechanism to add to a Li cell. It isn't a paper for the faint of heart, > however. It is "Nonaqueous Liquid Electrolytes for Lithium-Based > Rechargeable Batteries" by Kang Xu published in the Chemical Review, 2004, > Vol. 104, No. 10, pp. 4303-4417 and published on the web 09/16/2004. > > While I'm sure I don't get it 100% of the time I try to make sure I say, > "LiFePO4 cells have no theoretical self discharge mechanism." > This, according to all I have been able to find on the cells, is true. > Also, the most ardent anti-BMS people I have found have in fact done a lot > of searching of the scientific literature and came to the same conclusion. > It was not just something they made up to support their anti-BMS position. > > If you have other literature showing what the self-discharge mechanism is > please share it. > > On Fri, Jun 19, 2015 at 11:46 AM, Bill Dube via EV <[email protected]> > wrote: > > This "zero self-discharge" myth seems to be a common thread with the > > "anti-BMS" crowd. I don't know where this misinformation comes from. > > > > All cells have self-discharge. It is just a matter of degree. > > Also, the self-discharge varies from cell to cell. That's why you need a > BMS. > > These are well-documented facts for all those that care to > > investigate, either through the scientific literature or by simply > > systematically testing cells for themselves (as Lee Hart has done.) > > > > I strongly suspect the "zero self-discharge" myth comes from > > the same unscientific source that the anti-BMS myth has sprung from. > > > > Bill D. > > > > _______________________________________________ > > 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) > > > > > > -- > David D. Nelson > http://evalbum.com/1328 > http://www.levforum.com > _______________________________________________ > 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 [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150619/4ce67741/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)
