A protecting circuit for a battery used to power an electronic system includes a control circuit and a sensing circuit. The sensing circuit includes a tri-axial accelerometer having X, Y and Z axes. The tri-axial accelerometer is capable of detecting position changes of the battery and outputs through the X, Y and Z axes voltages that correspond to the position changes. The sensing circuit ultimately outputs a controlling voltage to the control circuit according to the voltages outputted by the X, Y and Z axes. When the battery is being installed onto or uninstalled from the electronic system, the outputted controlling voltage makes the control circuit OFF and the battery cannot power the electronic system. When the battery have been installed onto the electronic system, the outputted controlling voltage turns the control circuit ON and the battery can supply power to the electronic system.