Abstract

The condition of a storage battery of an internal combustion engine powered vehicle is tested automatically, and an indication of battery condition is provided to the service technician. The battery testing apparatus is connected to the positive (+) and negative (-) terminals of the battery to measure battery voltage under several different conditions. In particular, the battery testing apparatus measures battery voltage under open circuit conditions, while subjecting the battery to a predetermined AC load, and while subjecting the battery to a predetermined DC load. The battery testing apparatus also includes a temperature probe which measures the temperature of the battery. A digital computer control utilizes the measured open circuit voltage, the measured voltage under a predetermined DC load, and the measured voltage under an AC load (which represents dynamic internal resistance of the battery) and the temperature measurement to provide an indication of battery condition based upon these measured parameters and stored data for normal characteristics of the battery under test.