As for #1, 2V is probably ok but I don't have any test data or direct experience on that to back up my "probably ok" statement.
#3: Only when I have overcharged a TS cell has the voltage stayed above 3.38V for more than half a day. The best I've been able to determine from many different sources and scientific articles is that 3.38V the theoretical 100%SOC at room temperature. They have to sit for a day with no load after charging to determine if they are full and remain that way. Test with a charge procedure like charge to 3.6V and hold until current drops to 3A (for a 60Ah cell) and terminate charging. Wait a day and see what the voltage is. If you charge at a lower current then lower the ending voltage. I've found that charging to 3.455V and holding for ~45 minutes after the charger ramps down to ~100mA on my 200Ah pack slightly undercharges my pack as determined by the "charge and rest" method. #4: if they have already swelled slightly they have already lost some capacity. You might be able to get it to go away with compression for a while (I did on a 40Ah TS cell one time but no longer have the cell so don't know how it did/is doing) but I personally wouldn't spend the money on them for an EV application. I might for an electric push mower or something non-road going if the price were really cheap. Otherwise it isn't worth the hassle. A quality pack of cells are a joy to have. In my experience they don't drift and won't need balancing but once in a long while. I'm at over 2 years with my pack. On Wed, Sep 11, 2013 at 8:00 PM, EVDL Administrator <[email protected]> wrote: > Forwarding for Buddy Mills - please respond online. > > ----- > > I have some questions about some LifePO4 batteries that I can possibly > acquire. They are new but older 60ah batteries produced by the now RIP > International Battery. They have been sitting for about 11 months. The > voltage on the majority is above 2.5volts, but on some it is below. > > Now for the questions. > > 1. How far below 2.5 volts before I should write them off? > > 2. I was told that they are USA made Thundersky. Can anyone give me > any more insight, or has anyone had any experience with them. > > 3. After charging to 3.6 volts they rapidly drop to ~3.3 and then > hold. Is this normal for LiFePO4? I was expecting them to hold longer at a > higher voltage like a acid gel that I am used to using. > > 4. As for swelling of the case, I know that that is a sign of a > damaged cell, but all of them have a very slight bow, just enough to notice > when you try to band them together. Is this normal? Should I just compress > them and then band while compressed? > > I suspect that the whole group was charged and then stored. From what I > read, they should not have been stored at full charge, but what I really > want to know is whether I am wasting time and money on them. > > Thanks in advance for any info anyone can give. > > Buddy Mills > > 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) > -- David D. Nelson http://evalbum.com/1328 http://www.levforum.com Nokia Lumia 920 Windows Phone 8 _______________________________________________ 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)
