Hi Lee, Just wanted to check if it was 3rd-hand reports or not. If you say they were bad cells, they were bad cells.
Are there any testing statistics on the more modern Chinese cells (Yellow Thundersky, Blue CALB, etc)? Seems like people report a bad cell here or there but not the categorical failure to meet specs. One issue I have with testing hand-me-down or "freebie" cells is the cell may have been damaged by any number of mistakes in the charging or discharging regime. To get proper statistics, a person would have to buy a car's worth of batteries and then test each one. I am sure that some have done this. Any reports of what was found? I am leery of reports of "bad" cells by the average EV'er since there is a myriad of ways the cells can get screwed up with the many different balancing and charging scenarios. Cheers, Marcus On Tue, Sep 23, 2014 at 5:09 PM, Lee Hart via EV <[email protected]> wrote: > Marcus Reddish via EV wrote: > >> Are these the old white Thunder sky cells that failed? Seem to remember a >>> picture of them leaking. Is it possible folks charged those early cells >>> like they were lead and caused (or contributed to) the failures? I have >>> not heard of any bad "batch" since the white cells, which was ages ago. >>> >> > Willie2 via EV wrote: > >> The situation Lee describes dates to 2000-2003? Something like that. I >> know nothing of the situation but I believe they were LCP cells. >> Starting about 2005, LFPs were the preferred cells for conversions. I >> know of no quality or delivery problems with ThunderSky LFPs. >> > > My earliest ones were from a group buy organized by Victor Tikhonov in > 2003. They were white prismatic Lithium-Cobalt cells, in both 90ah and > 100ah models. Some of the 100ah cells were OK (maybe 3 out of 4 worked, but > didn't meet specs). *All* of the 90ah cells were junk. Some leaked, but the > main problems were low amphour capacity and excessive internal resistance. > Resistance on the 90ah cells was so high that they overheated even with a > 25 amp load. > > Maybe some of the purchasers abused their batteries and caused their > failures; but I certainly didn't. > > I've continued to borrow, barter, and buy various lithiums for testing. > Prismatics and cylindrical, LiCo, LiMn, LiFe etc. They have *consistently* > failed to meet specs. Typically, their amphour capacity and internal > resistance are out of spec, with large variations between cells, and a > number of bad cells mixed in with the good. The most recent ones were GBS > 100ah LiFe cells, tested just last year. The only exception has been A123 > 3.2v 2.5ah LiFe cylindrical cells; they were consistently good. > > I'm forever hopeful that the manufacturers will "get their act together" > and start delivering an honest quality product, and stand behind them with > a warranty. But so far, if I'd spent good money for a full pack of any of > these batteries (except A123), I would have been screwed. > > At the moment, I'm considering getting some Nissan Leaf cells to test. I'm > guessing that Nissan is likely to have made a *significant* effort to get a > good, quality product. I just have to make sure I'm not getting Nissan's QC > rejects! > -- > If you would not be forgotten > When your body's dead and rotten > Then write of great deeds worth the reading > Or do these great deeds, worth repeating. > -- Ben Franklin, from Poor Richard's Almanac > -- > Lee Hart's EV projects are at http://www.sunrise-ev.com/LeesEVs.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) > > -- Marcus Reddish -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140924/3302c969/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)
