Apparatus and method for managing a backup power supply for an aircraft cockpit voice recorder

A method for operating a backup power supply which has a capacitor and which provides electrical power to a recorder in an aircraft when power from a primary source is unavailable, said method comprising:

• commencing to charge the capacitor;
• measuring a first amount of energy that is stored in the capacitor during charging of the capacitor;
• discontinuing to charge the capacitor when the first amount of energy reaches a threshold energy level;
• upon electrical power from the primary source becoming unavailable, conveying electrical current from the capacitor to the recorder, thereby discharging energy from the capacitor;
• measuring a second amount of energy that is discharged from the capacitor;
• measuring an amount of time during which discharging occurs;
• and
• altering the threshold energy level in response to deviation of the amount of time from a reference value.

A method for operating a backup power supply which has a capacitor and which provides electrical power to a consuming device when electrical power from a primary source is unavailable, said method comprising:

• charging the capacitor;
• discharging the capacitor into the consuming device;
• measuring an amount of time during which the discharging occurs;
• measuring a first amount of energy that was discharged from the capacitor;
• defining a target energy level in response to the amount of time and the first amount of energy;
• thereafter, commencing to charge the capacitor;
• measuring a second amount of energy that is stored in the capacitor during charging of the capacitor;
• terminating charging the capacitor when the second amount of energy reaches the target energy level.