Patent ID: 7656126

Claim:
An abnormality detection apparatus for a secondary battery device having n secondary batteries (where n is 2 or more) connected in series for obtaining a high battery voltage corresponding to the n secondary batteries, the apparatus comprising: n voltage detecting circuits which output high-level signals at a normal voltage in a range from a lower limit voltage to an upper limit voltage between both terminals of each of the n secondary batteries; n N-channel field effect transistors having gates to which outputs of the n voltage detecting circuits are respectively supplied; and n P-channel field effect transistors having gates to which drain voltages of the n N-channel field effect transistors are respectively supplied, wherein, in the n P-channel field effect transistors, a drain of a 1st P-channel field effect transistor is connected to a source of a 2nd P-channel field effect transistor, and successively a drain of the 2nd P-channel field effect transistor is connected to . . . a source of an n-th P-channel field effect transistor, thus detecting an abnormality by a voltage obtained at a drain of the n-th P-channel field effect transistor.