Freakish, eh? How much does the state of charge change with a variation of 0.05V on a LiFePO4 cell?
Estimating say 90% of the SOC lies between 3.2 and 3.4 (0.2V of change). 0.1V = 45%, 0.01 = 4.5% then a variation of 0.05V on a cell could be a SOC variation of 22.5%. So a variation of 1mV could be half a percernt. Some of inaccuracy could be from the instrument itself as inexpensive DMMs may not be really good at measuring a single millivolt. I am just estimating, but I don't think that 0.05V change is necessarily "rock solid." Voltage is just a crapulous way to measure SOC on LiFePO4 cells. On Sun, Dec 29, 2013 at 4:16 AM, J Bills <[email protected]> wrote: > Totally. I'm not necessarily proud of it, but my 144v pack of lifepo4 must > have sat there for at least a year and a half and was rock solid 3.3v much > across the board the whole time, same as when I brought the crates home. > All within .05v of each other. > Almost freakish! > > early days on that project, I went ahead and picked up a single cell > lithium charger off of ebay for like $20 - I want to say it was 6A and I > remember the cutoff wasn't great but not too bad, might have been 3.8v? I > mean, don't quote me, never needed to use it, but just saying they are out > there and cheap. > > > -- 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/20131229/9e3252f2/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)
