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Technical Paper

How Synergetic is a Siesta for an Electric Sedan?

1983-02-01
830227
Lead-acid batteries were tested at the National Battery Test Laboratory at Argonne National Laboratory to determine the effects on the range of an electric vehicle of rest periods introduced during the vehicle use. Rest periods ranging from zero through four hours were chosen to simulate no break, a coffee break, a lunch break, and a work break. Preliminary results suggest that no increase in range can be expected as a result of the rest periods regardless of their length; moreover, it appears that in some cases a slight loss in battery capacity, and therefore in range, may occur as the battery cools during the rest period. Similar testing of the nickel/iron battery system is now underway.
Technical Paper

Impact of Mismatched Cell Characteristics on Lead-Acid Battery Charging

1983-02-01
830228
Over the operational life of a battery, the voltage characteristics of its individual cells become mismatched due to differences in self-discharge rates, individual charge efficiency, active material retention, etc. As these cell differences increase, excessive overcharging, operating temperatures, and/or electrolyte consumption result. In a series of tests performed on 6-volt, lead-acid modules, the degree of cell mismatch and the response of the modules to various charge methods were examined. The results show that after about 150 deep-discharge cycles, each module contained at least one cell whose full-charge voltage level was reduced. Prior to any decline in module capacity, cell voltage differences of more than 0.4 V were measured during charge. It was also observed that the application of a fixed battery voltage for charge control eventually caused excessive overcharging, elevated temperatures, and/or an extreme overvoltage condition on individual cells.
Technical Paper

Peak-Power Characteristics of Improved Electric-Vehicle Batteries

1982-02-01
820178
The technique used for measuring peak power available from a battery during a discharge sustained for a limited duration of time is developed and presented. In tests performed on nickel/ iron, nickel/zinc, and lead-acid electric-vehicle batteries at the National Battery Test Laboratory, it was shown that available peak power decreases with increasing depth-of-discharge (DOD). Most batteries tested deliver between 70 W/kg and 130 W/kg at 50% DOD but produce these peak powers with currents on the order of 700 A--a current well above the capability of most state-of-the-art electric-vehicle propulsion systems.
Technical Paper

Effects of Pulsed—Current Discharge Waveforms on Lead—Acid Traction Cell Performance

1982-02-01
820179
Chopper-type controllers commonly used in electric vehicle propulsion systems impose pulsed-current discharge conditions on the battery that influence both its internal power losses and available energy. In order to optimize propulsion system design, those discharge parameters that affect battery performance must be understood and characterized. In a series of tests performed on Exide EV-106 and EE-IV lead-acid traction batteries, a range of operating values were examined for current pulse frequency, average current discharge rate and pulse-to-average current level ratio. For each test, one parameter was selected as the variable while the other two parameters were maintained at fixed levels. Constant-current discharges were periodically performed during each test to relate battery performance for equivalent pulsed and constant current discharge conditions.
Technical Paper

Standard Test Procedures for Electric-Vehicle Batteries at the National Battery Test Laboratory

1982-02-01
820401
Standard test procedures used for electric-vehicle battery testing at the National Battery Test Laboratory at Argonne National Laboratory are described. The testing falls into two general categories--performance characterization and life-cycle testing. Activities within these categories include receipt, inspection, and installation of batteries, pretest conditioning, capacity verification, general open-circuit stand testing, partial depth-of-discharge testing, specific energy vs. specific power testing, simulated electric-vehicle profile testing, peak-power measurements, and life-cycle testing. General descriptions are provided for all tests; further detail is provided for the simulated electric-vehicle profile tests. The results from these simulated electric-vehicle profile tests are presented for a variety of lead-acid, nickel/iron, and nickel/zinc batteries.
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