Am I crazy or could bottom balancing be done at 3V with all the cells in parallel? They will all be perfectly balanced together at 2.75V or whatever you chose. Use a JLD and contactor with a resistive load to get down to the target voltage. Reconnect them in series and charge.
Please note that hooking them in parallel for balancing would only work at the extremes (low for BB, high for TB). If you hook them in parallel at half full (3.2v) they won't be balanced at either extreme. Obviously, this only would work for groups of individual cells, not pre-made modules. Are there any issues with this approach? On Fri, Mar 7, 2014 at 1:36 PM, Michael Ross <[email protected]>wrote: > There is a real possibility that BB'ing saves you more than you put into > it, but this is pretty speculative. > > There are hidden costs too - I have to come up with a resistive load than > can dump significant amps (rebar and an 200Ohm wire wound). Some people > just jack up the vehicle and spin it, but that is unappealing to me when I > can always use an excuse to weld something. You need contactors, and > JLD404s and shunts, stuff like that. Once you have it you can do more > packs. The tools are general purpose. > > I investigated DIY BMS and this all seemed easier. > > > > > > On Fri, Mar 7, 2014 at 3:06 PM, EVDL Administrator <[email protected]> > wrote: > > > On 7 Mar 2014 at 3:08, Michael Ross wrote: > > > > > So there is an appeal to bottom balancing in terms of life, cost > > > (ignoring labor, but we are DIY'ing so that is ignored always), and > > > ease of use. > > > > I see your point, but I don't agree that DIY labor cost is "ignored > > always." > > OK, it's not like I'm paying a mechanic, but every hour I spend under the > > hood or under the car is an hour I don't have for other things I like > doing > > just as much or more. > > > > But hey - if you have the time and you enjoy it, why not try? > > > > 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 > > For EV drag racing discussion, please use NEDRA ( > > http://groups.yahoo.com/group/NEDRA) > > > > > > > -- > 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/20140307/5fa24547/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) > > -- Marcus Reddish -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20140308/fba10f4c/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)
