Oh, sorry Bill maybe I got confused who I was replying to.
________________________________ From: paul dove via EV <ev@lists.evdl.org> To: Bill Dube <billd...@killacycle.com>; Electric Vehicle Discussion List <ev@lists.evdl.org> Sent: Wednesday, April 1, 2015 4:13 PM Subject: Re: [EVDL] Temperature rating (Was: ENERDEL Battery Experiences) That is the opposite of what you said before 70 degrees C is well over 104 degrees F ________________________________ From: Bill Dube via EV <ev@lists.evdl.org> To: Electric Vehicle Discussion List <ev@lists.evdl.org> Sent: Wednesday, April 1, 2015 2:10 PM Subject: Re: [EVDL] Temperature rating (Was: ENERDEL Battery Experiences) Here you go: http://www.ibt-power.com/Battery_packs/Li_Polymer/Lithium_polymer_tech.html and here is a good chart: http://www.mdpi.com/energies/energies-07-05675/article_deploy/html/images/energies-07-05675-g005-1024.png It is very common knowledge that warmer cells perform better than cooler cells for most battery chemistries. Chemical diffusion is more rapid at higher temperatures and allow the battery to deliver more power. What the battery can withstand without damage, and what particular elevated temperature is optimal is a matter of testing on the particular cell. In the Formula One kinetic energy recovery system (KERS) they operate their LiFePO4 cells continuously at greater than 70 Celsius. They get well over 20,000 w/kg at that temperature. (Your car battery gets about 300 w/kg to give you a frame of reference.) I have had a little bit of experience in squeezing maximum HP out of batteries over the years. :-) Bill D. At 12:18 PM 4/1/2015, paul dove wrote: >You gave no source. > >So one is better than none. > >I've never heard or seen any paper that claims 104F will affect performance. > > >From: Bill Dube via EV <ev@lists.evdl.org> >To: Electric Vehicle Discussion List <ev@lists.evdl.org> >Sent: Wednesday, April 1, 2015 1:13 PM >Subject: [EVDL] Temperature rating (Was: ENERDEL Battery Experiences) > >The 104 F (40 C) limit applies somewhat equally >to all Li-ion chemistries. The temperature is >limited because the electrolyte boils just >slightly above that temperature. Same type of >electrolyte in all Li-ion chemistries thus the same limit. > > The cell containment vessel can make a >big difference in this temperature limit, >however. Cylindrical cells can often hold >significant pressure while prismatic and pouch >cells can withstand less or perhaps no pressure. >Life a pressure cooker, the higher the pressure >of the electrolyte, the higher temperature you >can withstand. The A123 26650M1 cells (LiFePO4) >would withstand up to 100 Celsius (yes that is >correct) without damage. They weren't "rated" >that high, but they could withstand that >temperature. They were rated for 60 Celsius (140 F). > > Keep in mind that the cells will age >much more rapidly at that elevated temperature. >They perform better, however, and you don't hold >them that hot for very long. You must choose the >compromise between total life-span and >performance for the specific application, which >is typical for most things in life. > > I'm not sure where you are getting your >information. Better check more than one source. > >Bill D. > >At 10:42 AM 4/1/2015, you wrote: > >Jeff, I am not sure why performance at ambient > >temperatures should make anyone feel confident > >about a cell. LFP for instance, starts to have > >serious difficulties at 104°F if it is fully > >charged. That is certainly ambient here in > >North Carolina; and that is free air, not boxed > >up with significant amperage scooting about. I > >must tell you, I don't have an axe to grind > >here. I simply want to point out a better way > >to go. That is to get better information for > >all. And better testing with in the > >industry. ENERDEL just popped up on my radar > >is all. They have an website that is light on > >good information and I waded in. I am happy to > >see that behind the curtain they may have more > >on the ball. I have been scanning the course > >work you provided to me, and it is very > >nice. When ENERDEL discusses cycle life (around > >page 279) I can see they clearly understand the > >reactivity of the positive electrode at very > >high SOC and how temperature makes that much > >worse for the electrolyte. They clearly have > >good information to work with and probably are > >engaged with Dalhousie University or the spin > >off Novonix to get good testing done. I am duly > >impressed. I still have not figured out what > >chemistry they have chosen. From what I have > >seen so far, they speak assiduously, only in > >general terms regarding their own cells. If > >they are using some inferior chemistry and > >electrolyte package it is clearly not because > >they don't know better, so I bet they are > >OK. Provisional blessing on them until I am > >better educated. Thanks for taking the time to > >address this with me. Mike On Wed, Apr 1, 2015 > >at 10:19 AM, Jeff Major via EV > ><<mailto:ev@lists.evdl.org>ev@lists.evdl.org> wrote: > I doubt that > >EnerDel and its customers have overlooked > >anything as basic > as performance and life at > >ambient temperatures. It appears to me that > > >Hoegberg is comparing to some float stand-by > >application and then > misinterpreting the > >presented data. But whatever. They have > >millions of > cells in the field and no > >complaints of which I am aware. > > > >-------------- next part -------------- > An > >HTML attachment was scrubbed... > URL: < > > ><http://lists.evdl.org/private.cgi/ev-evdl.org/ > attachments/20150401/e6911ad9/attachment.htm>http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150401/e6911ad9/attachment.htm > > > > > > > > >_______________________________________________ > > > UNSUBSCRIBE: > ><http://www.evdl.org/help/index.html#usub>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>http://groups.yahoo.com/group/NEDRA) > > > -- > >To invent, you need a good imagination and a > >pile of junk. Thomas A. 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