On Thu, Jun 20, 2013 at 1:33 PM, <[email protected]> wrote: > Bill & David and all > > I am in total agreement and understand about the flow of current in series. > > Each cell is delivered an equal amount of power. >
Not the case. The higher resistance cell is delivered more power when charged > The electrons go through the pack equality so no cell receives more or > less energy. > > Not the case. The higher resistance cell receives more energy when charged > The resistance losses I am addressing, do not change the volume of current > delivered to each cell in series. > Correct It is the differences between cells, which also include resistance, which > changes the capacity retained in the cells. Capacity retained in cells can > and is different if cells or modules lose a part of that energy at a > greater > rate then others during charging. > Not correct. Capacity is not directly affected by internal resistance > This is nothing new > > To balance a NiMH pack a common method is to over charge the pack with the > full cells bleeding energy as heat. The current is exactly the same to each > of the cells but the NiMH chemistry is capable of losing a substantial > amount of energy as heat. The fully or nearly fully charged cells have > higher > resistance readings and because of this create more heat then cells still > gaining capacity. > > While resistance does go up with SOC that is not the cause of lower charge efficiency in NiMH, as lee already explained. > As I stated before resistance in a cell is not a constant. As a cell > reaches a full charge the resistance increases. I have measured this so > there is > no doubt, cells with a higher state of charge lose a greater amount of > energy as heat. > > This is correct, but not a direct cause of imbalance. If I had only one method of selection in using modules it would be > resistance readings. I have gone though a 1000 used NiMH modules and the > closer > you can keep resistance readings the better your results will be. > > Agreed > If cells have even slight differences in resistance, they don't all heat up > exactly equal on charge and discharge. > > True. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20130620/f1f88eee/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)
