"No one I know of charges fully." The eBike and light EV crowd are not so fortunate. (The area I am most concerned with.) They typically buy no name packs with, BMS of unknown function and provenance, and chargers with all the stickers removed and unknown internal tweaks.
My first off the reservation pack, would probably have been a nice unit were it not for the charger which poured it on a 60V for 16 cell series of LFPs. I couldn't tell you what exactly it did, but I would plug it in with the vehicle sitting in the hot sun and let it charge until finally I thought about it. Potentially running the average cell voltage to 3.75V. Admittedly, with the charger removed the resting voltage was, 56V ==> 3.5 / cell. I have to think that the charger running at 60V was bad just the same, creating the conditions for activation of the electrolyte damage. Net result, pack did not last very long. On Mon, Jun 1, 2015 at 1:46 PM, tomw via EV <ev@lists.evdl.org> wrote: > Yes, I am aware of that. For about 5 years I have been advising people not > to charge to over around 3.45V which is about where the exponential > increase > in the curve starts at typical charge currents. I published a number of > cell measurements and charge curves around that time showing there is less > than 2 Ah charge between 4.45V and 3.55V on 180Ah cells, so not much gain > in > charge by going there unless you use a shunt balancing BMS which I do. > Shunt turn-on varies from 3.48V to 3.52V over my 36 cells, so every 4 - 6 > charges I charge the highest cells to 3.54 - 3.55V and check the shunt LEDs > to ensure they are all on giving me peace of mind that the pack is still > balanced. The rest of the time I just do partial charges. Many people > only > charge to less than 3.45V every charge. No one I know of charges fully. > The manufacturer's spec is final CV charge at 0.05C to 3.6V which is below > the maximum voltage for the cells. You also have to keep in mind that > although there are significant differences in the rates of side reactions > in > cells of different chemistries, the rates are fairly low, so the effects > accumulate slowly over years unless you significantly over charge or > discharge a cell. I don't think anyone expects these prismatic cells to > last 10 or more years with less than 10% capacity loss. I'll be happy if > my > pack still has 90% nominal capacity in 7 years, which is only 1 1/2 years > away. Then I'll replace it with a wrecked Leaf 30kWh pack :^) > > > > -- > View this message in context: > http://electric-vehicle-discussion-list.413529.n4.nabble.com/Success-tp4675905p4675947.html > Sent from the Electric Vehicle Discussion List mailing list archive at > Nabble.com. > _______________________________________________ > 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/20150601/a728353c/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)
