If the batteries have been replaced and the charge remaining hasn't moved from 30% for three hours its likely the power module has an issue. To verify this using a DC voltmeter check the voltage across one of the batteries; they are wired together so they should be the same. If the DC voltage is above 13Vdc the power module is OK. If not, the replacement part number is 97-599 for the non-Lithium battery system. If you have a Lithium or green battery call Tech Support at 800-888-8458.