A battery charge and discharge protection device adapted to be coupled to a load device and a charger device, and adapted to be installed with two batteries, said battery charge and discharge protection device being characterized by comprising: a battery polarity detecting unit adapted to be coupled to the batteries, and configured to detect, with respect to each of the batteries, whether the battery is correctly installed or reversely installed, so as to generate a first detection result; a battery type detecting unit disposed and configured to detect, with respect to each of the batteries, whether the battery is rechargeable or non-rechargeable, so as to generate a second detection result; and a charge and discharge control unit coupled to said battery polarity detecting unit and said battery type detecting unit being adapted to receive the first and second detection results, and adapted to be further coupled to the load device, the charger device and the batteries; when said charge and discharge control unit determines based on the first detection result that at least one of the batteries is reversely installed, said charge and discharge control unit disabling power transfer from the batteries to the load device, and disabling power transfer from the charger device to the batteries; when said charge and discharge control unit determines based on the first detection result that both of the batteries are correctly installed and determines based on the second detection result that both of the batteries are rechargeable, said charge and discharge control unit connecting the batteries in parallel, enabling power transfer from the batteries that have been connected in parallel to the load device, and enabling power transfer from the charger device to the batteries that have been connected in parallel; when said charge and discharge control unit determines based on the first detection result that both of the batteries are correctly installed and determines based on the second detection result that only one of the batteries is rechargeable, said charge and discharge control unit enabling power transfer from the battery that is determined to be rechargeable to the load device, and enabling power transfer from the charger device to the battery that is determined to be rechargeable. a battery polarity detecting unit adapted to be coupled to the batteries, and configured to detect, with respect to each of the batteries, whether the battery is correctly installed or reversely installed, so as to generate a first detection result; a battery type detecting unit disposed and configured to detect, with respect to each of the batteries, whether the battery is rechargeable or non-rechargeable, so as to generate a second detection result; and a charge and discharge control unit coupled to said battery polarity detecting unit and said battery type detecting unit being adapted to receive the first and second detection results, and adapted to be further coupled to the load device, the charger device and the batteries; when said charge and discharge control unit determines based on the first detection result that at least one of the batteries is reversely installed, said charge and discharge control unit disabling power transfer from the batteries to the load device, and disabling power transfer from the charger device to the batteries; when said charge and discharge control unit determines based on the first detection result that both of the batteries are correctly installed and determines based on the second detection result that both of the batteries are rechargeable, said charge and discharge control unit connecting the batteries in parallel, enabling power transfer from the batteries that have been connected in parallel to the load device, and enabling power transfer from the charger device to the batteries that have been connected in parallel; when said charge and discharge control unit determines based on the first detection result that both of the batteries are correctly installed and determines based on the second detection result that only one of the batteries is rechargeable, said charge and discharge control unit enabling power transfer from the battery that is determined to be rechargeable to the load device, and enabling power transfer from the charger device to the battery that is determined to be rechargeable.