On 1 Jul 2019 at 15:24, paul dove via EV wrote: > I think people get confused with the term balancing. It is pretty much a carry > over from lead acid batteries where the take all the cells to boiling to get > them to the same voltage at the end of charge.
That's what I'd call equalization -- forcing current through already-charged cells or batteries, overcharging them, in order to fully charge others that aren't yet. Balancing lead batteries is different from equalization, and similar to balancing any other cell or battery. I'm not an expert, but from what I can tell, regardless of the chemistry, balancing cells or batteries in series usually involves either bypassing charging current around full cells or modules, or actively using other cells/modules to charge the cells/modules with lower charge levels. The goal of balancing shouldn't be so much to get all cells/modules to the same voltage, but rather to get them to the same state of charge (usually full). But generally voltage and SOC are considered congruent for balancing purposes, even though they're not really. As for periodic deliberate deep discharges, again, I'm not an electrochemist or anything, but my understanding is that it's not all that healthy for most batteries. (NiCd is an exception, apparently, but only if you're careful not to reverse them.) I suspect that when a discharge to or near 0 SOC seems to increase capacity, it's actually because it's somehow recalibrating the firmware that manages the battery. The capacity is still there, it's just that the BMS doesn't think it is. Running the battery flat, or nearly so, sort of reboots or recalibrates the BMS. I own a netbook that "finds" some capacity that it's "lost" when I do this. But I don't like it. I just don't think that's how you treat a battery if you want to show it you like it. David Roden - Akron, Ohio, USA EVDL Administrator = = = = = = = = = = = = = = = = = = = = = = = = = = = = = EVDL Information: http://www.evdl.org/help/ = = = = = = = = = = = = = = = = = = = = = = = = = = = = = Note: mail sent to "evpost" and "etpost" addresses will not reach me. To send a private message, please obtain my email address from the webpage http://www.evdl.org/help/ . = = = = = = = = = = = = = = = = = = = = = = = = = = = = = _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
