I am admittedly new to this, but I think there is a recipe for very long life of LFP cells. Almost forever - which is to say the rest of the vehicle gives out first.
Build the cells right, so there are no mechanical problems (we don't have much control over that as end users, and this confounds us). That means they have properties not too far from each other when they are born. Some people buy extra cells and pick them to be similar. A good idea. Balance them so they don't care if they go to zero...because they do it together. Never overcharge them. Operate them from SOC of 20% to 80% for a conservative guess. It can be done with a simple cut off system). I bet 10% to 90% works with a good pack. Never charge them so they get plated inside. Which is to say, limit the current when the temperatures drop in the cell. Jack thinks they heat themselves from the current flowing which makes sense, but I use really low power compared to cars so maybe I should look after the cold temperatures more. Never charge them too fast so they get hot inside (pay attention to regeneration). Operate them within a well built system - no loose terminals, etc. (not sure about the whole of etc.) Maybe we check individual cell voltages, every now and then - every 1000 cycles? Just to give us confidence they are staying together. If you do these things there is no mechanism for them to fail. Or I have haven't heard what it is yet. Here I diverge from the DIY fold and refer to research, not anecdotal evidence. I think there may be a lot of confounding factors, so there are a lot of opinions based on results where the actual causes are not known. To bad we don't have a place to send our dead cells for inspections (looking for plating, and dendrites, queer electrolytes, whatever. Anyway, that is what I hope for now. I also hope for even better batteries and think they are coming soon enough. The little eggs of graphene coated silicon sound very good. On Sat, Mar 8, 2014 at 10:59 PM, EVDL Administrator <[email protected]> wrote: > On 8 Mar 2014 at 14:52, Michael Ross wrote: > > > There is a certain appeal to having a pack that will last nearly forever > > I'll say. Who WOULDN'T want that?! > > However, lithium isn't the chemistry for "nearly forever." > > If you want a "nearly forever" battery, what you want is nickel-iron. I > confess I haven't personally met any, but I understand that there are > original NiFe cells made by Edison himself (well, at least with his brand > name on them) still in working condition. We're talking batteries close to > a century old! > > Some flooded nickel-cadmium batteries also are very long-lived. > > Regardless, good luck with your project. Keep us posted. > > 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/20140309/9faeabd3/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)
