1. A device comprising: non-volatile memory; a controller in communication with the non-volatile memory, wherein the controller is programmed to move data from a volatile memory to the non-volatile memory upon a loss of power of a primary power source of the volatile memory; and a backup power supply providing temporary power to the controller and the volatile memory upon the loss of power of the primary power source, comprising: a capacitor bank with an output terminal; a connection to a voltage source that charges the capacitor bank to a normal operating voltage; and a state-of-health monitor that is programmed to generate a failure signal based on a voltage at the output terminal of the capacitor bank.