Agreed, you have to charge and discharge once to measure with precision the coulombic efficiency, but if you are not doing research you don't necessarily need to do it more than once.
If you understand how a population of batteries behave regarding coulombic efficiency, you can simply apply the damaging high state of charge and temperature and after you have accumulated the same overall time as a many cycle regime, you could estimate whether a test specimen is within specification. Or you can take samples from different sources and make comparisons without resorting to many cycles. One of Dahn's salient points is that below some threshold of SOC% and temperature, you are accomplishing nothing to stress the battery. The only reason to cycle low is to check the capacity. Then he goes on to show how much "accelerated life testing" never actually exposes the cells to significant. damaging conditions. 10000 fast cycles could have very minimal time or none ate levels of SOC% that cause harm. The test sounds good on a website, or spec sheet, but reveals nothing useful. If you try to get information on salient test conditions from a manufacturer or worse, a distributor, you may never actually talk to anyone who is knowledgeable, or see graphs with labeled axes, and so on. Comparisons are nearly impossible because test conditions are not standardized. A big user like Tesla, for instance, gets involved in HPCE (high precision coulombic efficiency) testing because it is currently the only way to make rational decisions in a timely manner. But many cycles of charging should be minimized to levels depending on the decisions to be made. Development and quality control require different protocols. MR On Fri, Oct 14, 2016 at 6:48 PM, Roger Stockton via EV <firstname.lastname@example.org> wrote: > > > Measuring the coulombic efficiency requires cycling the cell(s), as what > one is interested in is how much of the energy delivered to the cell on > each charge cycle is *not* recovered on the subsequent discharge. > > Cheers, > > Roger. > > _______________________________________________ > UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub > http://lists.evdl.org/listinfo.cgi/ev-evdl.org > Read EVAngel's EV News at http://evdl.org/evln/ > Please discuss EV drag racing at 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> Mobile and Google Phone 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/20161014/04a12169/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)