Why is it you think I am making this up? I have no reason to do anything, but report what has been found using the new testing. I just read the papers, talked to the people, and watched that video enough to follow it.
"Automotive product validation is pretty rigorous." Apparently, they did it wrong. It is rigorous, and expensive, but not sufficient. Nissan did it wrong, GM chose to use an inferior cell, but added cooling and fared better than Nissan. Fiskar could have made better choices. None of them knew better. They did this because the testing was not good enough. This has been the state of Li ion testing for decades. A consequence is that people like BIll look at 300 or 500 cycles and think that is OK. We see 3000 cycles on a spec sheet and think that is hooey; but maybe 5000 or 10000 cycles is really possible. We have been flying blind. This is the whole point - The old style testing is inadequate, if it is not set up right. If it is set up right it takes a very long time to detect cell damage because it is not not accurate or precise enough. Nobody does it long enough, because it is too expensive. This has held back cell development. It is common that the testing is not very useful because prior to HPC it took to long to see a problem. You can run a lot of cycles, for months and reveal nothing. It looks good on paper if no one knows enough to be critical of it. Blah blah blah. It is what it is. Anecdotally, I have a couple of LFP packs on my LEV that are crap after maybe 50 cycles. I do know that I have charged them as high as their BMS let them go out in the hot sun. The larger one used to get me 24 miles. Last time about 15. The smaller pack used to get me 13 now 8. I can't get my commute done any more with both of them freshly charged. Is this sort of high heat and high charge the reason? I don't know, but it fits. I definitely charged them at temps above 35°C and probably left them sitting fully charged at 40°C for a many days. The science says, I did them more harm sitting that I did riding or charging. Before I spend another thousand on new packs I am going to figure out how to eliminate conditions that cause damage. On Wed, Apr 1, 2015 at 10:55 PM, Jeff Major via EV <ev@lists.evdl.org> wrote: > > > > > On Wednesday, April 1, 2015 12:42 PM, Michael Ross < > michael.e.r...@gmail.com> 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. > >>>>>>>>>>> 40degC ambient is what you're concerned about, isn't it? Not > uncommon for automotive. My point was they surely tested there, and likely > higher. Automotive product validation is pretty rigorous. I can't imagine > they overlooked it. > > > > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: < > http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20150402/694dfd51/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) > > -- 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/20150402/e1f7c9f7/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)
