Battery e.g. lithium iron phosphate/lithiated graphite battery, charging state determining method for photovoltaic field, involves determining charge state corresponding to measured current at end of test period using calibration curve

摘要

The method involves placing a battery in an open circuit during a recovery period, where the battery has a predetermined nominal voltage. A constant test voltage is applied to terminals of the battery during a predetermined test period, and a current at end of the test period is measured. A charge state corresponding to the measured current at the end of the test period is determined using a calibration curve, and the test voltage is lower than the nominal voltage of the battery phase when the battery is in a charging phase.