Testing Batteries for Vehicular Applications: III . Selection and Characterization of a Power Battery

Abstract

The problem was to find an acceptable “power” battery (i.e., a high power density battery to deliver short time acceleration pulses) for an electric commuter vehicle concept powered by a dual battery system. A number of batteries were tested, both Pb‐acid and Ni‐Cd. The best battery was a Ni‐Cd aircraft starting battery. It could deliver 14 consecutive 1900W, 10 sec acceleration power pulses. It was calculated that about 180 lb of battery would be required for the particular power plant design envisioned. The high cost and scarcity of Cd militated against the use of a Ni‐Cd battery. The next best candidate was a Pb‐acid aircraft starting battery designed for high current drains for short time periods. It, too, delivered 14 consecutive 1900W, 10 sec pulses. In addition, it had sufficient energy capacity to provide some low speed range in the event of failure of the “base‐load” energy battery. It had a power density of 70 W/lb at an energy density of 2 Whr/lb. About 270 lb of this battery would be required for the “power” battery pack. A Delco‐Remy 2HN‐11A military battery was tested to yield design data for the power plant. From these data, a battery was designed which would fit into an available lightweight container. Prior to this, a 2HN‐11A modified battery was tested to confirm the design. Test results confirmed the designed capacities.Several of the design batteries were built. Each consisted of seven cells containing 11 plates per cell. One of the batteries was tested. It delivered 15 consecutive 2500W acceleration power pulses to 10.5V. It weighed 32 lb; hence, the entire power pack would weigh 256 lb. Since the 11‐plate cell performed so well, it was hoped that a 9‐plate cell might just deliver adequate power. A 27 lb weight reduction would be realized. However, it could not deliver adequate power when tested. Nothing could be obtained at 2500W. The voltage fell immediately below 10.5. In fact, only 1.8 min were obtained at 1900W.