"I think that it is possible that people are confusing *theoretical* cell chemistry with that of *practical* cells. "
It is like a bunch of people simply don't want to understand that things are not uniform across the field, that there is old tech that is being surpassed, and that some things are turning out very well. I would restate, " I think it is possible that people don't recognise that some old and inferior cell designs do not represent what is possible, demonstrable and manufacturable." On Wed, Jun 24, 2015 at 12:05 AM, Roger Stockton via EV <ev@lists.evdl.org> wrote: > Michael Ross wrote: > > > Cells, when designed well, don't offer a ready path for any electrons > that > > aren't controlled by external circuitry. This how cells for medical > > implants can last for 10 or more years. > > I rather suspect that cells for medical implants are *primary* (i.e. > non-rechargable) cells, not secondary cells, and so this seems likely to be > an apples-to-oranges sort of comparison. It is reasonably easy to point to > any number of primary cell chemistries that offer shelf lives of 10yrs, > just as it is reasonably difficult to point much of any secondary cell > chemistry that will not significantly self-discharge in less time. > > > If some poorly designed cells do offer a way to discharge spontaneously, > > that is a bad thing. It is incorrect to indict all lithium cells with > > this concept. > > You have referenced Linden's Handbook of Batteries previously in this > thread; this might be a good time to revisit it. > > My copy may be an older edition than yours, as the chapter in mine that > covers lithium secondary cells doesn't cover LiFePO4, however, it clearly > states self-discharge rates for several (if not all) of the various lithium > chemistries that it covers. The self-discharge rates vary from one lithium > chemistry to another, and they do distinguish between irreversible capacity > loss and self-discharge. > > I think that it is possible that people are confusing *theoretical* cell > chemistry with that of *practical* cells. While there may (or may not) be > a self-discharge mechanism in an ideal cell of some chemistry (perhaps > LiFePO4), practical cells tend to be at least some distance from ideal and > may well have unintended or undesirable second or third order reactions due > to unintentional contamination/impurities or intentional additives that > provide some benefit that outweighs the disadvantage of introducing some > amount of self-discharge. > > I did not take the time to read the secondary lithium sections thoroughly > to see if they offer any explanation for the stated self-discharge rates > for the various lithium chemistries discussed, however, it is quite clear > that it is incorrect to attribute some magical properties to lithium > intercalation and announce that cells relying on this process cannot > possibly exhibit self-discharge. > > Cheers, > > Roger. > > _______________________________________________ > 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/20150624/28051d0f/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)
