I'll add my 13 kWh worth 8^): Pack: 45 ThunderSky 100Ah (TS-LFP100AHA) in a serial arrangement; split into 3 groups of cells. Age: Cells were purchased October 2009 and conversion was built in early 2010. I bought the car in July 2010. The first two years, I drove it in the summer and parked it all winter to work on it. Last year, I drove it almost all winter. Miles: 21,700 miles driven. About 870 charging cycles. I charge at home, overnight to full voltage. I charge at work also. About 1/3 of work charges have been to full voltage, others have been to less voltage as I removed the vehicle from the chargers after 3 hours or so.
I drive 25 miles to work, charge there, and drive 25 miles home. So, except for the extreme episodes noted below, my batteries have mostly seen 870 charges of half capacity. Each cell has a MiniBMS board. Also, the Elcon charger tapers voltage and terminates charge at about 3.5V per cell. The MiniBMS boards all have shunts to dissipate excess power once each cell reaches 3.5V. The MiniBMS alerts and terminates charging at 3.6V on any cell. With the pack balanced, the charger tapers and terminates charge without the MiniBMS being involved; it is a backup. Because of the shunt resistors, I am top balanced. There have been two episodes where cells were abused. Two cells went to 0 volts when my pack was significantly unbalanced and I didn't know it. After getting home, I finally heard the low-voltage alarm (too quiet). Those cells are still in operation, but probably weaker. The second episode, some cells were below 2.5V, but not at zero volts. The pack was better balanced at that time. The batteries have 1/2" foam insulation and a top plastic cover to keep heat in. They also have 90W aquarium heaters under each block of cells. The heaters are also wired with thermostats. The intention is to hold cells to 70F with the heaters while charging and plugged into AC. The thermal mass and insulation would be used while driving to keep battery performance up. In reality, I drove all last winter with only the insulation and no heaters. I plan to finish connecting heaters for this winter driving. The cells do droop as they get cold. The car is kept garaged at home (garage is insulated, but not heated), but charges without cover at work. Mike www.evalbum.com/2778 > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of David Nelson > Sent: Wednesday, October 09, 2013 12:33 AM > To: Electric Vehicle Discussion List > Subject: Re: [EVDL] Li-ion life (WAS: Range) > > Ok, I'll add my info. > > Pack: 40 ThunderSky 100Ah (TS-LFP100AHA) in a 2p20s arrangement > Age: 4yrs, manufactured November 2009, in service since January 2010 Miles > Driven: 17,200 Amp-Hours delivered: 38,600 Capacity remaining: unknown* > but have hit 80% DoD several times without issue Top charge voltage: 3.455V > (charger tapers current to ~100mA, no-load voltage after 12h rest is 3.36V) > BMS used: none, split pack voltage monitor (AKA Lee Hart BattBridge > variation) Temperature Management: no, but I don't charge when the case > temp is below 0°C > Location: Kelso, WA > > > -- > 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) _______________________________________________ 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)
