The WF-68100-AD Series Converter-Chargers will charge the 12-volt house battery if installed. A battery does not have to be installed for WF-68100-AD Series Converter-Charger’s operation. When a battery is installed, three reverse polarity fuses are installed to protect the converter circuitry. The fuses are located on the rear panel of the enclosure near the AC power cord. This feature prevents permanent damage to the converter from a battery connected into the circuit backwards. In addition to protecting the converter-charger, the reverse polarity fuses are the main connection between the converter-charger and the DC fuse board of a distribution center.