On Mon, Apr 21, 2014 at 9:45 AM, EVDL Administrator <evp...@drmm.net> wrote: > On 21 Apr 2014 at 12:34, Michael Ross wrote: > >> I don't think bottom balancing is cult-ish. (It IS rude to talk bout it >> that way.) It is just complicated. > > I can see why you might think it rude. > > The term "cult" might be a bit strong. But personally, I do see an an > element of a sort of "religion" in some of the bottom-balancing folk. Others > may not feel the same way.
In all fairness, your statement can be equally applied to the "BMS only" crowd. As Michael and Damon point out, this is not as simple as one thing works and another thing doesn't. There are many parameters to consider in how a battery pack has been treated before anything can really be said about a particular method. I was fortunate enough to get 40 good cells. Now that I have 4 years and 18k miles on my pack and it is still going strong and is not getting out of balance with no balancing being done on any charge, you can see why I question the "requirement" of having a top balancing BMS whether it is active or passive. I purposely chose to go without the top balancing BMS I started out with because no one could show me the theoretical reason to have a top balancing BMS and I couldn't find one in all the researching I did either. For my climate and setup my data is still showing that a BMS is not necessary. Maybe if I lived where Jukka lives I would have different results. I know I'm not the only one with great results with no BMS. Blanket statements from either "camp" make them appear cultish. It may be that, as Jukka pointed out about the formation charges, I was actually fortunate to have very slowly (10A into 20 paralleled 100Ah cells) charged my cells to 4.00V initially and for a short time after installation. Now I charge to 3.455V/cell average. I don't charge if the case temp is at or below freezing, and I rarely discharge past 70%DOD. As for other types of lithium batteries besides LiFePO4, I can't say for sure, I haven't tested or researched them enough. -- David D. Nelson http://evalbum.com/1328 http://www.levforum.com _______________________________________________ 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)
