Gm Global Technolgoy Operations, Inc.

Van V Riesberg, Jr

Robert J Nowakowski

An apparatus for and method of indicating when the battery in a motor vehicle is discharging is disclosed in which the battery voltage during vehicle operation is monitored and compared to a stored value representing the open-circuit voltage of the battery measured prior to the vehicle engine being cranked for starting. An indication that the battery is discharging is provided only after a discharging condition, i.e., the battery voltage is less than the stored value, is detected at each of a predetermined member of consecutive timed intervals.

Vehicle battery discharging indicator

Dry mixed and sintered PVC battery separators having predetermined thicknesses less than 0.012 inch, porosities greater than about 50%, and pores sufficiently small to substantially prevent interplate 'treeing' (i.e., less than about 10 microns average) are produced by: mixing about 3% to about 15% by volume of leachable, pore-forming particles with the PVC particles; scraping the particle mix into a layer less than about 0.012 inch thick; sintering the PVC into a continuous strip; compressing the strip in the temperature range of about 250.degree. F.-450.degree. F. to a thickness no greater than about 50% of its as-sintered thickness; thereafter immediately allowing the strip to recover much, but not all, of its as-sintered thickness; and cooling the strip to substantially fix the separator thickness at the recovered thickness. The leachable, pore-forming particles are preferably formed in situ by the thermal degradation of a gasifiable filler such as sodium bicarbonate.

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Anderson, IN, United States of America

Van V Riesberg, Jr