Patent ID: 7626353

Claim:
A self diagnosis method for a mobile type information terminal which comprises secondary batteries; a fuel cell; a charging means for charging the secondary batteries from the fuel cell and a boost DC/DC converter which is interposed between the fuel cell and the charging means and has a function for stopping operation when there is an abnormality in the fuel cell; wherein a first charge current command value and a second charge current command value which is smaller than the first charge current command value which is sent by the charging means and a logic signal corresponding to normal/abnormal output voltage of the boost DC/DC converter are utilized and the method comprises: a step for charging the secondary batteries using the first charge current command value when the fuel cell is started; a step for changing the charge current command value to the second charge current command value and charging the secondary cells over a prescribed time in the case where the logic signal is a signal that indicates abnormality of the boost DC/DC converter; and a step for charging the secondary batteries by changing the charge current command value back to the first charge current command value after the prescribed time has elapsed.