>From the paper " small amounts of stack pressure lead to increased capacity retention over uncon- strained cells.
" Use some pressure. Cheers, John Lindsay > On 4 Sep 2016, at 6:37 AM, paul dove via EV <[email protected]> wrote: > > You might want to rethink that theory. > > https://www.princeton.edu/~spikelab/papers/103.pdf > > Sent from my iPhone > >> On Sep 3, 2016, at 3:20 PM, Cor van de Water via EV <[email protected]> >> wrote: >> >> Paul, >> Every time the cell is at the top of charge, it will expand. >> Don't compress and you will likely burst it in short order. >> I have taken apart packs that were used *with* the Leaf BMS >> so charging has always kept them under 4.115V max but when I remove >> the nuts that hold a stack in compression, I cannot get the nuts back on >> unless I use heavy clamps to compress the stack back to original size. >> If Nissan was happy to add heavy steel end plates to an EV that needs to >> be as light as possible, just to keep the modules compressed, then who >> am I to decide that I should omit those? >> But don't take my word for it, try it yourself. >> And let us know how you fare. >> >> BTW, I have seen what happens to modules that are overcharged to 4.3 >> Volts. >> Even with the heavy compression, some cells managed to generate enough >> pressure to buckle some of the module walls and the guys that took the >> pack apart had to make sure they were not in the line of "fire" when >> they undid the nuts of the end plate - nut and wrench went flying! >> At the normal 4.115V max, this excess will not happen, but the pressure >> can easily be enough to damage the thin module sheet metal walls that >> are not design to contain pressure, only to keep the cells aligned. You >> can also pull the bus bars off the cells due to the working of the stack >> of cells when uncompressed. Take your chances or follow the Nissan >> design, it is your own choice and your own quality of work. >> Regards, >> >> Cor van de Water >> Chief Scientist >> Proxim Wireless >> >> office +1 408 383 7626 Skype: cor_van_de_water >> XoIP +31 87 784 1130 private: cvandewater.info >> >> http://www.proxim.com >> >> This email message (including any attachments) contains confidential and >> proprietary information of Proxim Wireless Corporation. If you received >> this message in error, please delete it and notify the sender. Any >> unauthorized use, disclosure, distribution, or copying of any part of >> this message is prohibited. >> >> >> -----Original Message----- >> From: paul dove [mailto:[email protected]] >> Sent: Saturday, September 03, 2016 12:46 PM >> To: Cor van de Water; Electric Vehicle Discussion List >> Subject: Re: [EVDL] Alternatives for Golf Cart and Forklift batteries >> >> >>> Lithium stack to the frame of the lift, you are aware that the Leaf >>> cells (and probably other Li cells as well) must remain under >>> compression or risk bursting the cell pouches open, inside the >> modules? >> >> I don't believe that at all what proof do you have the cells need to be >> compressed? A cell should only expand when it's damaged. >> _______________________________________________ >> 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) > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160903/c9d8c37a/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) > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20160904/96367f29/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)
