How long do the batteries last?
Li-Ion batteries are good for 500 complete charge/discharge cycles. One cycle consists of discharging the pack from 100% state of charge (SOC) to 0% SOC. Realistically, drivers will not completely discharge their pack. More likely, drivers will drive the car for 50 or 100 miles then plug it back in to charge it up to 100% SOC. Driving only 50 miles is only a partial discharge, roughly using 20% of the charge. If a driver continues to drive 50 miles every day and recharges every night, then after 5 days they would complete the equivalent of one charge/discharge cycle.
In estimating the life of our batteries, you can multiply the number of cycles by the range. Thus, 500 cycles times 250 miles/charge works out to 125,000 miles, but our estimate is a more conservative 100,000 miles. However the cycle life of 500 cycles is based upon performance that is more challenging to the battery cells than our application. We believe that our pampered batteries will achieve more cycles due to temperature control of the batteries and minimizing the maximum charge voltage.