Apparatus for detecting battery pack deterioration during discharge mode and method for inhibiting deterioration detection of a significantly drained battery pack during charging mode

A detection apparatus for deterioration in a battery pack consisting of a series assembly of a plurality of battery modules during discharging, said apparatus comprising:

• current detection means for detecting a discharge current of said battery pack;
• voltage detection means for detecting a discharge voltage of said battery pack;
• temperature detection means for detecting a battery temperature of said battery pack;
• storage means for previously storing reference data which are obtained by actually measuring a gradient of a distribution of a discharge voltage with respect to a discharge current in a deteriorated test battery pack with a battery temperature value of said test battery pack using as a variable;
• calculation means for calculating a gradient of a distribution of a plurality of discharge voltage values detected by said voltage detection means with respect to a plurality of corresponding discharge current values detected by said current detection means and for calculating on the basis of said reference data a deterioration reference gradient of distribution of the discharge voltage with respect to the discharge current which is to be held at the temperature value detected by said temperature detection means;
• deterioration judging means for comparing said gradient with said deterioration reference gradient to judge whether deterioration occurs or not;
• and
• display means for receiving an output of said deterioration judging means to display the output.