May, 2009
A battery pack comprising seven, 3.5 V, 31 Ah Li-ion modules was obtained from Amita Technologies Inc. It is a typical low-cost, lithium ion-battery pack supplied for powering electric scooters. A single module from a seven-module pack has been operated in the laboratory under a simulated, simple urban, electric scooter schedule. The battery delivered 53 Wh during each of the completed 2300 cycles. Operating temperature was in the range between 35 to 45 C, and the time required for charging was 13.5 min (40 to 90% SOC), which increased to 16 min towards the end of life. Based on the energy requirements of the ECE 47 electric scooter urban drive cycle, it is considered conservative to predict that a battery pack comprising seven of these modules should provide between 20 000 and 25 000 km before replacement is required. The excellent cycle life recorded is attributed in part to the resistance-free charging algorithm used in these experiments. This procedure maintains very high charge rates (thereby reducing charge times), whilst avoiding undue decomposition of the solvent and electrode materials.
