Even though marketing likes accelerated life testing , and it gives a higher comfort level to everyone, accelerated life testing can just take resources away from more serious investigation ; particularly when the life you are trying emulate is 10 to 20 , or more years. Are you going to wait five years to learn what is happening? After years of this approach to Li ion development many people are simply confused , who are designing, manufacturing, purchasing , and using cells end products . The specs given on battery life for cells that we buy retail border on useless for comparing products and estimating service life.
This is where the work at Dalhousie got its motivation. (I know this from calling Dr. Dahn on the phone and having conversation.) They wanted to advance Li-ion and other battery technologies to advance without waiting through over long test periods. Their approach was to jump up the accuracy of testing by orders of magnitude. In a nutshell they built top of the line test equipment using very high quality current sources, they performed testing in thermal chambers maintaining extremely steady, elevated temperatures, and so on, all to reduce environmental and measurement noise and uncertainty. Through these means they were able to detect very small levels of cell deterioration and malfunction, while NOT cycling the cells; instead simply maintaining the damaging conditions and stopping occasionally to examine cell function (capacity, resistance, etc.), the test periods were drastically reduced from accelerated life testing protocols. Freed from the desire to say, " these cells lasted this long at such and such a cycle rate, and number of cycles, " Dahn's lab simply created the conditions that cause trouble and kept the cells there. A typical cell life test runs the tests at conditions that are pseudo-realistic, but at a high cycle rate, which essentially doesn't expose the cells to damaging conditions for a lengthy time until a very long time has elapsed. The damage occurs with high SOC%; cycling cells simply gives them long rest periods at conditions we already know are not damaging. Some their first discoveries were that small tweaks to electrolyte composition could greatly improve or reduce cell life. On Sep 24, 2016 7:10 AM, "George Tyler via EV" <ev@lists.evdl.org> wrote: > Accelerated life testing is a science on it's own. A friend of mine has > made a career out of it, runs a network of Labs for a huge medical > electronics company. We worked for the same company twice through the > years, he did the testing for a lot of the electronic products I designed. > What separates the men from the boys is creating test plans that DO work > the same as real life, if you can't do this it is a waist of time or worse. > You create a model, test it, and old when it aligns with reality do you do > the actual testing. Say you model is to run the product at elevated > temperature, you run one at ambient +20 deg, another at +30. +40 etc etc, > then measure time to failure, draw a graph. Where the graph suddenly take > off for the sky is the point you must keep below. There is much more to it > as well. > > > -----Original Message----- > From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of Jukka Järvinen > via EV > Sent: 24 September, 2016 2:09 AM > To: Michael Ross; Electric Vehicle Discussion List > Subject: Re: [EVDL] 2nd life for lithium batteries > > Rarely what one can get for free is useless. People even sleep in > cardboard boxes. > So is the idea to push forward the responsibility to recycle? This is no > business per se. If something it's just smarter use of existing resources. > > What it comes to better electrolytes.. that is HARD! The testing cycle to > confirm lifetime and usability is way too long. Accelerated aging tests are > not the same at all to real life use. While I have to admit I was wholly > impressed by the Hydro Quebec battery research lab. Boy do they have toys > there! :D (droool) Advancements in R&D are available as we can now see more > deeper and more accurately with color-SEM and such. > > Does it not go without saying that one should not use cell-murder (tm)? > BMS has to be done right. > > -Jukka > > P.S.- Dear Santa. I would like to have a $10bn to research more. Thank You! > > 2016-09-23 14:47 GMT+02:00 Michael Ross via EV <ev@lists.evdl.org>: > > > Advances in testing are just beginning to drive more effective research. > > For example tiny adjustments in electrolyte components can yield big > > improvements. The testing is faster and provides more granular > > investigations. > > > > Re LFP you mistreat them and they die a quick death, but stationary > > apps you can treat them well. > > > > EV battery packs may not be optimal compared to purpose built > > stationary packs but they are far from useless. > > > > Mike Ross > > > > On Sep 23, 2016 4:43 AM, "Jukka Järvinen" <akkuju...@akkujukka.fi> > wrote: > > > > > Usually the internal resistance is growing much faster than the loss > > > of capacity. So if you use the pack in very low power application > > > you will > > be > > > able to use the pack for some time (several years). This is for LCO, > > > LMO and NMC. Maybe NCA too (cannot say for sure yet as I do not have > > > usage > > data > > > from those yet). > > > > > > Basically the combination of low voltage chemistry, cool temperature > > > during use and shallow cycles will provide long life for the cells. > > > LFP > > has > > > at least 5 to 10 years more calendar life than those mentioned above. > > Then > > > again LTO-cells should have even slower rate of unhoped side > > > reactions at the chemistry level compared to LFP. But LTO has hard > > > time to compete against LFP net cost. Which is dirty cheap. > > > > > > Stationary batteries are designed for the use. Meaning their cost to > > > buffer each kWh and provide power is much much less than the EV type > > cells. > > > Currently for large utility scale units the cost to buffer is around > > > one cent per kWh. > > > > > > -Jukka > > > > > > > > > > > > > > > 2016-09-23 8:45 GMT+02:00 Michael Ross via EV <ev@lists.evdl.org>: > > > > > >> I believe batteries, and Li-ion as well as future designs will not > > degrade > > >> much for a decade and more when properly managed. Understand that > > 'Lithium > > >> batteries" covers a large and disparate group of designs. So, any > > comment > > >> can be quibbled over. > > >> > > >> What is known now, a loss of 85% would probably be accompanied by > > physical > > >> and chemical damage that might render them unreliable at greater loss. > > But > > >> certainly Li-ion if managed well could be useful down to 30% SOC. > > >> > > >> The rub here is "well managed." Proper management will depend on > > >> the > > exact > > >> electrode and electrolyte chemistry, the construction of the cell, > > >> temperature of operation and storage, particularly at high SOC%. > > >> and so on. > > >> > > >> Anything we say is dependent on a host of variables. I think the > > >> body > > of > > >> knowledge will grow and all these difficulties will drop in > > significance. > > >> > > >> You did not say in what application the degradation to 70% SOC > > >> would > > occur > > >> but safe to assume you meant in cars. Tesla already committed to > > creating > > >> rid based applications for "degraded" batteries. Their belief is > > >> that stationary applications are far easier on the cells than > > >> mobile and automotive apps. Allowing us to believe there is a very > > >> good chance that car batteries will likely have a second life. > > >> > > >> Does anyone know how low the capacity of a battery can fall before > > >> it is no longer > > >> useful, and how long will that take? At least 50%, probably more. > 15% > > is > > >> too low for current technologies. > > >> > > >> For example, can the capacity shrink down to 15% SOC and still > > >> provide useful power, how long would that take? Depends. > > >> > > >> It will continue to improve. > > >> > > >> Mike > > >> > > >> > > >> On Fri, Sep 23, 2016 at 12:32 AM, Larry Gales via EV > > >> <ev@lists.evdl.org > > > > > >> wrote: > > >> > > >> > Most scenarios assume that Lithium batteries for EVs should be > > replaced > > >> > when they degrade to 70-80% of their initial capacities, after > > >> > which > > >> they > > >> > might serve as storage batteries for the grid, or a house. Does > > anyone > > >> > know how low the capacity of a battery can fall before it is no > longer > > >> > useful, and how long will that take? For example, can the capacity > > >> shrink > > >> > down to 15% and still provide useful power, and how long would > > >> > that > > >> take? > > >> > > > >> > > > >> > > > >> > Thanks, Larry > > >> > > > >> > -- > > >> > Larry Gales > > >> > -------------- next part -------------- An HTML attachment was > > >> > scrubbed... > > >> > URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/ > > >> > attachments/20160922/84aa5308/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) > > >> > > > >> > > > >> > > >> > > >> -- > > >> 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/ > > >> 20160923/7d4a7fbd/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) > > >> > > >> > > > > > -------------- next part -------------- An HTML attachment was > > scrubbed... > > URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/ > > attachments/20160923/74e062c3/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) > > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/ > 20160923/61bdfa43/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) > > > _______________________________________________ > 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) > > -------------- next part -------------- An HTML attachment was scrubbed... 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