Wow. I have a pack of 45 ThunderSky 100Ah cells. I used to feel they were a distinct notch below cells like CALB. Now, I'm not so sure.
I just crossed 26,000 miles in almost 4 years with my pack. It has a range of 50+ miles, but my typical commute is 23 miles, each way, with a recharge at each end. So, I've got about 1100 charge cycles in the pack. For the first two years, I parked the car all winter to work on it. The last two winters, I've driven it almost every day. I've only parked it on days when the snow was deep enough to cause problems for a low-slung sports car. I'm running MiniBMS on each cell and top-balancing with shunts on each BMS board. I know from experience that the shunts are not enough to get the pack in balance, but they are working to keep it in balance. Also, when the pack is properly balanced, the charger shuts off automatically, so the BMS are just a safety measure on the high voltage side. I have two cells that I abused badly within the first year. My MiniBMS was alerting, but I couldn't hear it at highway speeds. I took the two cells to 0V. I have been babying them for 3 years, and the same cells are still in the pack, but I think they are starting to go. I am looking for some spares to replace them, if anyone is taking apart a ThunderSky 100Ah pack. That episode was when I realized that my pack was 20% out of balance. I had to top up the low cells by 20Ah to bring them up to the high cells. Once I had that all worked out, the charger shut off automatically instead of the BMS cutting AC power. The shunts had been trying to balance the pack, but they just didn't have time enough to make much difference in cell balance when the charger was still in its bulk current phase. Once the charger tapers current, near the final voltage, the shunts have more chance to bring things into balance. Winter performance was very sluggish, but I've now got battery heaters now that help quite a bit. Mike www.evalbum.com/2778 > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of Al > Sent: Sunday, April 20, 2014 8:42 PM > To: Electric Vehicle Discussion List > Subject: Re: [EVDL] self-discharge of CALB 180Ah LiFePO4 cells > > I have to agree with Cruisin. I took a chance on Lithium with CALB cells, and > man have I got burned. My pack is just shy of 2 years old. It has been very > lightly used for only 10,000 miles and perhaps 200 cycles. The cells are > supposed to be 100Ah. Even when new I bench tested a few at .3C and only > got 95Ah. Now the pack is below 80AH according to my BMS. At this point I > have no idea what my range will be each time I drive as I have had several > cells lose 25% capacity out of nowhere. So much for the cheaper than lead > mantra. > > 1000+ cycles - Not a chance > 100,000 miles - You're kidding right? > 10 years - In your dreams. > > Al > > > CALB cells (and many others) are typical Chinese junk. > ----- Original Message ----- > From: "Cruisin" <[email protected]> > To: <[email protected]> > Sent: Sunday, April 20, 2014 7:05 PM > Subject: Re: [EVDL] self-discharge of CALB 180Ah LiFePO4 cells > > > > After selling CALB cells for over 5 years and using them in my own > > conversion, I can tell you from experience the following. At least 15% of > > the cells will change so much in the first year the BMS will react to your > > disadvantage of early charging termination and early over discharging. A > > one > > year warranty that is promised is hocus. the second year will experience a > > 10% failure with no warning of a cell. This makes your car unusable. > > Further > > experience with other Chinese cells is no better, or worse. I now sell and > > use the Nissan Leaf module that is half the price and so far no failures > > like the CALB. I would not ever recommend a CALB cell to any customer. > > Those > > that are pushing the cells like EVTV have inventory they want to unload > > before their is no more demand for Chinese cells. My customers who have > > converted to the Volt and Leaf cells, made by the same S Korean > > manufacturer, are really happier with the results. No more stagnant at > > rest > > loses that you have experienced. Look at what cells are used in the > > popular > > plugin cars that are required to provide a 8 year warranty in California, > > no > > Phosphate. CALB would be out of business if required to provide a 8 year > > warranty. They don't even recognize their one year warranty. You wonder > > why > > you are having problems, wake up and smell the coffee. > > _______________________________________________ > 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) _______________________________________________ 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)
