Dave, Do you think if LiFePO4 are BB'd and limited to operating between 20% and 80%, or 10% and 90% SOC that they will have degraded cycle life?
They don't have any fancy elements in them (Co, Ni, Mg) Which helps cost a lot. They are safer (higher burn temperature). I read that some OEM EVs with Li Ion packs limited there SOC range between 25% and 75% - only 50% of capacity actually used. That makes sense if you are willing to over design that much. You can charge faster if you never go near 100%, and very long life is attractive. I think the S Model is limited in SOC range too. BUT I don't remember where that came from. I have a salvaged pack of 40Ah Thundersky cells for my little pedal assist EV, and I am thinking of operating this way; so I am interested in opinions. I am willing to do the work to BB them and set up a cut off system. It is a good learning experience. I am thinking of using 17 cells instead of 16 and charging with 60V and not worry about a charging cut off. Just a discharge cut off. On Thu, Mar 6, 2014 at 6:54 PM, EVDL Administrator <[email protected]> wrote: > True, lithium (even LiFePO4) beats NiMH for specific energy. However, I'm > not yet sure that it can beat NiMH for cycle life. Look at the RAV4-EVs > running around on their original NiMH batteries at 100k miles and more. > > Practically speaking, though, NiMH wasn't available when the EV world > needed > it, so the EV world has moved on. Even if NiMH were "liberated" today, I > can't imagine enough manufacturers jumping on the wagon to make for a > competitive marketplace like we have in lead and is developing in lithium. > > Suppose a LiFePO4 battery lasts 5 years and an NiMH battery lasts 15 years > but costs 3 times as much and has less specific energy. That probably > doesn't sound attractive to EV hobbyists, but there might be some EV > engineers who would appreciate the reliability, and EV bean-counters who > might want reduced warranty claims. Isn't Toyota pretty well married to > NiMH > for those reasons? They've had all these years for NiMH to prove itself to > them in Priuses. > > But for most, I suspect it's a weak pull against the intensity of current > trends and fashion. I'd guess that EV engineers don't much think about > NiMH > any more. They go straight to lithium because (1) it's available and (2) > everyone else does. > > Interestig to muse about what might have been. If Ovonics hadn't dropped > the ball in selling NiMH's future to GM, they COULD have been a major > player > in the EV business. Ah well, the EV world is thickly populated with such > missteps. > > David Roden - Akron, Ohio, USA > EVDL Administrator > > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > EVDL Information: http://www.evdl.org/help/ > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > Note: mail sent to "evpost" and "etpost" addresses will not > reach me. To send a private message, please obtain my > email address from the webpage http://www.evdl.org/help/ . > = = = = = = = = = = = = = = = = = = = = = = = = = = = = = > > > _______________________________________________ > 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) > > -- Put this question to yourself: should I use everyone else to attain happiness, or should I help others gain happiness? *Dalai Lama * Tell me what it is you plan to do With your one wild and precious life? Mary Oliver, "The summer day." 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) 550-2430 Land (919) 576-0824 <https://www.google.com/voice/b/0?pli=1#phones> Google Phone (919) 631-1451 Cell (919) 513-0418 Desk [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140306/7cfbbac4/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)
