In a phone conversation, Dr. Dahn told me that LFP starts deteriorating a 104°F when fully charged.
You can simply not charge fully. Exactly how not fully? I don't know. Also there may be differences depending on the form factor, source of the electrode, electrolyte compositions, and so on. No rules of thumb here, but you may want to prudently reduce the charge cutoff voltage. The difference between 3.4V and 3.7 could be huge in terms of cell life, particularly if the pack gets hot when charged. This is complicated by the general rule not to ever, ever charge Li ion cells in your residence. Mike On Mon, Jun 1, 2015 at 10:40 AM, tomw via EV <ev@lists.evdl.org> wrote: > My garage is a steel building with no insulation. In summer it typically > is > 10 to 15 F warmer than outside temperature. You can feel the IR radiation > from the walls and roof, like being in an oven, and the metal is hot to the > touch. In June through August it is typically 100 to 118 F inside. My ev > has been garaged there for 5 1/2 years, 40k+ miles. I live in high desert > where the nights are typically 35 F lower than daytime highs, so the > highest > temperature the battery reaches just sitting in the garage is significantly > below the daytime high temperature in the garage since the cells have > significant heat capacity and are in insulated boxes. > > The pack has been up to 110 to 115 F a number of times in the hot months > after longer drives. Seems to just keep going. Each year I do a test drive > to discharge the pack to about 28% SoC, then floor the accelerator to draw > 3C from the pack and see if the LVC alarm on the minibms triggers. So far > it > has not. Range likely has decreased a bit, but this test indicates it has > not decreased all that much. My cells are LiFePO4, different than the Leaf, > but according to Dahn worse with regard to temperature effects, so I don't > think you need be too concerned. On the hottest days I sometimes park the > car in the shade of a tree rather than leave it in the garage. > > Winter brings the opposite problem, but I have Farnum heaters under > aluminum > sheet that the batteries sit on and 1/2" insulation in the boxes. Keeps > them at the set point of 65 F in the winter when it is plugged in in the > garage and above 50F if left parked outside for 4 - 5 hours. > > > > > > -- > View this message in context: > http://electric-vehicle-discussion-list.413529.n4.nabble.com/Success-tp4675905p4675945.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/20150601/5cb534fb/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)
