Battery protection device and method for DC power supply

A battery protection device for a direct current power supply, comprising a monitoring unit, a direct current power supply, a chargeable battery unit, and load units, and further comprising:

• a first branch circuit unit and a second branch circuit unit which are connected with each other in parallel;
• wherein, one end of the parallel connection is connected to said direct current power supply, and the other end of the parallel connection is connected in series with said load units through said chargeable battery unit;
• and
• wherein, said first branch circuit unit comprises a second control unit and a first isolation unit that are connected in series, and said second branch circuit unit comprises a third control unit and a second isolation unit that are connected in series;
• said first isolation unit and said second isolation unit are components which have characteristics of being conductive in a forward direction and cut-off in a reverse direction, and the conductive directions of said first isolation unit and said second isolation unit are opposite;
• when said direct current power supply supplies power normally, said first isolation unit is in a conductive state, and said second isolation unit is in a non-conductive state;
• said monitoring unit, connected with said direct current power supply, said chargeable battery unit, said second control unit and said third control unit respectively, and used to monitor working states of said direct current power supply and said chargeable battery unit, and send control commands to said second control unit and said third control unit by following way:
• when said monitoring unit detects that said direct current power supply supplies power normally and said chargeable battery unit is fully charged, controlling said second control unit to switch off and said third control units to switch on, to make said direct current power supply disconnect to said chargeable battery unit and supply power to said load units;
• when said monitoring unit detects that said DC power supply supplies power abnormally, controlling both said second control unit and said third control units to switch on, to make said chargeable battery unit supply power to said load units.