Tips: The battery voltage is low but the battery cannot be charged for more than 10 hours.Judging from the phenomenon it is the fault of battery and charging circuit, which can be inspected according to the following procedures.1. Check whether the input and output voltage of the charging circuit is normal. 2. If the charging circuit is in normal input and abnormal output, disconnect the battery to test again. If it is still abnormal, it is the fault of the charging circuit.3. If the charging circuit has normal input and output after the battery is disconnected, it indicates that the battery has been damaged because of the long term charging, long time placement, due life period.