I get a lot of flack for this, but Li - ion cells don't function the way PbSO4 and others do. They are essentially bi-stable. You put and ion on the cathode (charge it) and it nestles between some platelets of graphene within a stable pocket of carbon atoms around it. Until you create a potential and current path in the discharge direction nothing happens. Before the "until" point there is nothing to cause the ion to move, unlike other battery cells. This is called intercalation.
If there is self discharge of a Li-ion cell happening when it is not in a circuit, it is a fault in its manufacture. There is a lot of variety of manufacturing expertise and quality. We could, any one of us, make a functional Li-ion cell in our garage, but it would be unlikely to have a long life or good performance. One good way to treat a new cell is to charge it for long term storage is charge to about 50% DOD (or SOC if you prefer). This ensures that the degradation that occurs when a fully charged cell sees too high temperature. This degradation is a loss of capacity however, not necessarily a loss of charge % relative to the whatever functional cathode, anode and electrolyte is left. A shitty cell of a particular chemistry will be alike to the same cell made well made and formed properly of the same chemistry. At 50% SOC you theoretically are seeing the nominal cell voltage. But I warn you that you may not really know the true midpoint cell voltage. Spec sheets are notoriously vague to incorrect on this point. Also it is not easy tp tell anything about SOC from voltage. a tenth of a volt can be a lot of difference in charge, a characteristic of Li-ion generally. You might see the voltage change 0.3V from 20% to 80% soc. Every change in chemistry can effect this. Do you have LiFePO4? One of the combinations of Li with nickel, aluminum manganese, etc.? THe nominal can range from 3.2V to 4.2V depending. Do you really know what the cells are made of? You said "high voltage after six years, a high nominal voltage for one could be a low voltage for another. > I just tried some Lipo cells that have been on the shelf for..about 16 > years,, > without any charging > > They had almost full voltage.. !! Wow, thats interesting > Some day I will do a voltage capacity plot of them, I have 3pcs > > Sony Energytech from Ericsson Phones, > size code VP383562A A1 > > year/Date code:(??) > WHK16B > > -- 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> Mobile and Google Phone [email protected] <[email protected]> -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160530/32cad21f/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
