John, The BMS will autonomously balance cells with just 12V connected, provided that all 96 cell inputs are powered. There are essentially two tricks to use a shorter battery and still have the BMS do its balancing trick with only minimal extra circuitry and work, there is a third way but that essentially is to manually re-program a processor to do the balancing work that the BMS does when 96 cells are connected.
The two tricks: 1. Add another opto-coupler (there already is one for the mid-pack disconnect) and "alias" the top 16 cells to already connected cells. Yes, it will be connected double, but the whole concept of balancing prevents those cells from being drawn down more than others. 2. Add an external power supply that provides more than the 10mA that the BMS balances and powers each of the 16 unconnected inputs, so you need about 48V power and divide it in 16 steps of 3V to keep the BMS working. It will not be too happy about the unbalance, so you might up the voltage to make it better in line with the other cells (typically more around 4V each) but that is the concept. Hope this clarifies, 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: EV [mailto:[email protected]] On Behalf Of John Lussmyer via EV Sent: Monday, December 19, 2016 6:22 PM To: Electric Vehicle Discussion List Subject: [EVDL] Leaf BMS Another Leaf question. How will the BMS react if there are only 40 modules in the string, instead of 48? -- Try my Sensible Email package! https://sourceforge.net/projects/sensibleemail/ _______________________________________________ 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) _______________________________________________ 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)
