April 2004
Electric Applications Inc. (EAI) staff have been monitoring a fleet of electric vehicles (EVs) manufactured by the Frazer Nash (FN) company for several years. As part of a continuing development process, the suitability of two new gelled-electrolyte batteries for use in these vehicles has been evaluated. The batteries, manufactured in China by the Vision and Lichpower battery companies, have been cycled under simulated EV conditions developed specifically to mimic the operating conditions of the FN EVs.Two Vision batteries delivered 40 cycles under simulated EV service before their capacities decreased to a specified cutoff level. The performance of the batteries was recovered with an equalization procedure, but after a total of 90 cycles (which included another pass through the equalization process), both units had experienced a significant, permanent capacity loss. By contrast, the Lichpower units operated for 90 cycles before requiring equalization. These batteries also experienced a permanent loss in performance during the 90 cycles, but this decrease was less than that experienced by the Vision units. The performance of both technologies under the simulated FN duty is considered unsatisfactory as it represents only 90 days of field service. A Vision and Lichpower battery were discharged to 3 V at a low current (i.e., 1 A) in order to simulate extreme deep-discharge duty. Both batteries performed very well ¾ their capacity was still acceptable after the completion of 25 cycles. The results from this program, combined with previous studies on the Sonnenschein gelled-electrolyte battery, suggest that the EV performance of this battery is superior to that of the Vision and Lichpower designs. The inexpensive Chinese batteries, however, could still be cost-effective in selected applications.
