"Jack Richard came to this conclusion years ago. He said Li-Ion batteries work better hot. "
Years ago, before improvements in testing, that may have been applied to "work better," but definitely, high temps are not a recipe for "works longer." Also "Li-ion" is far too broad a stroke for any pronouncement. Some chemistries and formats should simply not be compared. On Nov 17, 2015 9:47 AM, "dovepa via EV" <[email protected]> wrote: > > Jack Richard came to this conclusion years ago. He said Li-Ion batteries > work better hot. It's in one of his videos I watched. I don't remember > details but it was during all the Leaf problems in Arizona. > > Sent from my Verizon Wireless 4G LTE smartphone-------- Original message > --------From: brucedp5 via EV <[email protected]> Date: 11/17/2015 2:19 > AM (GMT-06:00) To: [email protected] Subject: [EVDL] A math formula can > model li-ion pack aging, Pyrite pack > > > 'Cheap-materials fool’s-gold pyrite battery' > > > http://www.idtechex.com/research/articles/simple-mathematical-formula-models-lithium-ion-battery-aging-00008646.asp?donotredirect=true > Simple mathematical formula models lithium-ion battery aging > Nov 11, 2015 Penn-StateU,Volvo Group Trucks Technology > > Hybrid electric vehicles, cell phones, digital cameras, and the Mars > Curiosity rover are just a few of the many devices that use rechargeable > lithium-ion batteries. Now a team of researchers has a simple mathematical > formula to predict what factors most influence lithium-ion battery aging. > > Lithium-ion batteries function by moving lithium ions from the negative > electrode to the positive electrode and in the opposite direction when the > battery charges. How often and exactly how that battery is used determines > the length of a battery's life. Complex models that predict battery aging > exist and are used for battery design. However, faster, simpler models are > needed to understand the most important factors that influence aging so > that > battery management systems in hybrid electric vehicles, for example, can > better control lithium-ion batteries. > > "We started out by making models specifically for Volvo's batteries that > were tuned to their specific chemistry and showed that the models matched > experimentally," said Christopher Rahn, professor of mechanical > engineering, > Penn State. "We then focused on simplifying the aging models. Now, we have > the ultimate simplified aging model down to a formula." > > According to Rahn, a battery ages, or degrades, whether it is sitting on a > shelf or used. The main cause of lithium-ion battery aging is the > continuous > formation of the solid electrolyte interphase (SEI) layer in the battery. > The SEI layer must form for the battery to work because it controls the > amount of chemical reactions that occur in the battery. As the battery is > continually used, however, small-scale side reactions build up at the SEI > layer, which decreases battery capacity -- how much of a charge the battery > can hold. Models allow researchers to understand how different factors > affect this degradation process so that longer-lasting, more cost-efficient > batteries can be made. > > Hybrid electric vehicles combine the efficiency of electric vehicles with > the power and longevity of gasoline-powered vehicles because they have both > a gasoline-fueled conventional internal combustion engine and an electric > motor powered by batteries. The electric motor uses regenerative brakes, > which take the energy that was moving the car forward and convert it to > mechanical energy, putting the electric motor into reverse and slowing down > the car. The electric motor acts as a generator and takes the electricity > that is generated to store in batteries for future use. This is in contrast > to conventional braking systems in which braking energy is wasted when > friction converts the energy into heat. > > According to the researchers, this new simple aging formula takes into > account only the factors shown to most influence lithium-ion battery aging > by affecting growth of the SEI layer, which include state of charge, how > often the battery charges/discharges completely, operating temperature, and > current. > > "Car companies can use this formula to quantify which factors are > contributing the most in aging and focus more on them and less on all of > the > other factors that don't play as much of a role," added Tanvir Tanim, > graduate student in mechanical engineering, Penn State. > > As part of the study, Tanim and Rahn compared the accuracy of their formula > to that of more complex models using commercially available batteries. They > found that their simple formula works just as well. > > "Whenever you simplify a model, there are some things lost," said Rahn. "We > have complicated models because they are very accurate. As you simplify, > you > have to justify every assumption that you make. I wasn't sure we could > simplify the model down to a formula. It's pretty amazing to explicitly see > how things depend on one another." > > Rahn and Tanim have already seen the benefits of having a simple formula to > model battery aging by using it to show that increasing the temperature of > lithium-ion batteries in hybrid electric vehicles extends the life of the > battery, which is contrary to what most researchers think. This effect was > something that Volvo had previously seen with their batteries, and using > this aging formula, Rahn and Tanim could explain why. > > Learn more at the next leading event on the topic: Electric Vehicles: > Everything is Changing. USA 2015 [ > http://www.idtechex.com/electric-vehicles-usa/ > ] on 18 - 19 Nov 2015 in Santa Clara, CA, USA hosted by IDTechEx. > [© idtechex.com] > ... > > http://news.psu.edu/story/378093/2015/10/30/research/simple-mathematical-formula-models-lithium-ion-battery-aging > Simple mathematical formula models lithium-ion battery ... > Oct 30, 2015 - Now a team of Penn State researchers has a simple > mathematical formula to predict what factors most influence lithium-ion > battery aging. > > > > > http://www.autoevolution.com/news/swiss-scientists-develop-cheap-battery-made-of-materials-that-are-abundant-102034.html > ... Colloquially called the “fool’s gold battery,” it consists of iron, > sulfur, sodium and magnesium. Considering that all these elements are in > plentiful supply, the experimental battery should be a lot cheaper than the > ones currently on the market. This means that giant storage batteries could > be built on the cheap and used stationary in buildings or next to power > plants, for instance. > > The team of researchers, made of Maksym Kovalenko, Mark Walter, and their > colleagues at Empa’s Laboratory of Thin Films and Photovoltaics, have > combined a magnesium anode with an electrolyte made of magnesium and sodium > ions. Nanocrystals made of pyrite - more commonly known as fool’s gold - > serve as the cathode. Pyrite is a crystalline iron sulfide. Scientists have > found that the sodium ions from the electrolyte migrate to the cathode > during discharging. And when the battery is recharged, the pyrite > re-releases the sodium ions. > > The result? Storing electricity. EMPA claims this so-called > sodium-magnesium > hybrid battery already works in the lab and has several advantages. For > one, > the magnesium as the anode is far safer than highly flammable lithium ... > [© 2015 SoftNews NET] > > > > > For EVLN EV-newswire posts use: > http://evdl.org/evln/ > > > {brucedp.150m.com} > > -- > View this message in context: > http://electric-vehicle-discussion-list.413529.n4.nabble.com/A-math-formula-can-model-li-ion-pack-aging-Pyrite-pack-tp4678722.html > Sent from the Electric Vehicle Discussion List mailing list archive at > Nabble.com. > _______________________________________________ > 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/20151117/f90d92e6/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... 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