On 3/2/2013 9:52 PM, Mike Nickerson wrote:
I once took two ThunderSky cells to 0 volts and was able to recover them both. I drove further than I should and had a pack that was rather severely out of balance without realizing it. I charged them carefully with fans on them to keep them cool. I expect they are still my weakest cells, but they are still running in my car two years later.
I have found that while they seemed to recover, their internal resistance had gone up. In the case of one cell, it went up a LOT (like 4 times its initial value). This caused excessive voltage drop under load, and its voltage would rise too quickly on charge.
A cell that is damaged like this is an ideal setup to cause a disaster if the EV doesn't have a BMS.
-- I do not waste my life in friction when it could be turned into momentum. -- Frances Willard -- Lee A. Hart, http://www.sunrise-ev.com/LeesEVs.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)
