Battery pack and cordless tool using the same

An electric device configured to be connectable to a first battery pack including plural battery cells, a positive terminal and a negative terminal, and connectable to a second battery pack including plural battery cells, a positive terminal and a negative terminal, the electric device comprising:

• a first positive terminal configured to be connected to the positive terminal of the first battery pack;
• a first negative terminal configured to be connected to the negative terminal of the first battery pack;
• a second positive terminal configured to be connected to the positive terminal of the second battery pack;
• a second negative terminal configured to be connected to the negative terminal of the second battery pack;
• a first control signal terminal configured to receive one of a signal indicative of the number of the plural battery cells of the first battery pack and a signal supplied from a first protection circuit for protecting the plural battery cells of the first battery pack;
• a second control signal terminal configured to receive one of a signal indicative of the number of the plural battery cells of the second battery pack and a signal supplied from a second protection circuit for protecting the plural battery cells of the second battery pack;
• a switching element connected to a current path between the first and second positive terminals and the first and second negative terminals;
• and
• a controller configured to control the switching element to be turned off based on the signal input to one of the first and second control signal terminal.

A system comprising:

• a first battery pack including plural battery cells, a positive terminal and a negative terminal;
• a second battery pack including plural battery cells, a positive terminal and a negative terminal;
• and
• an electric device configured to be connectable to the first and second battery packs, the electric device including:
• a first positive terminal configured to be connected to the positive terminal of the first battery pack;
• a first negative terminal configured to be connected to the negative terminal of the first battery pack;
• a second positive terminal configured to be connected to the positive terminal of the second battery pack;
• a second negative terminal configured to be connected to the negative terminal of the second battery pack;
• a first control signal terminal configured to receive one of a signal indicative of the number of the plural battery cells of the first battery pack and a signal supplied from a first protection circuit for protecting the plural battery cells of the first battery pack;
• a second control signal terminal configured to receive one of a signal indicative of the number of the plural battery cells of the second battery pack and a signal supplied from a second protection circuit for protecting the plural battery cells of the second battery pack;
• a switching element connected to a current path between the first and second positive terminals and the first and second negative terminals;
• and
• a controller configured to control the switching element to be turned off based on the signal input to one of the first and second control signal terminal.

A system comprising:

• a first battery pack including at lease one battery cell, and a first protection circuit configured to protect the battery cell;
• a second battery pack including at least one battery cell, and a second protection circuit configured to protect the battery cell;
• and
• an electric device configured to be connectable to the first and second battery packs, the electric device including:
• a cell housing unit configured to house the first battery pack and the second battery pack;
• a first terminal configured to be electrically connected to the first battery pack, the first terminal being provided at the cell housing unit;
• a second terminal configured to be electrically connected to the first protection circuit, the second terminal being provided at the cell housing unit;
• a third terminal configured to be electrically connected to the second battery pack, the third terminal being provided at the cell housing unit;
• a fourth terminal configured to be electrically connected to the second protection circuit, the fourth terminal being provided at the cell housing unit;
• a switching element configured to control a current flowing through the first terminal and the third terminal;
• and
• a controller configured to control the switching element based on signals received by one of the second terminal and the fourth terminal.