Systems, devices and methods are provided for measuring battery current. The pupil position and convergence detection system is part of an electronic system incorporated into the ophthalmic lens. When the estimated accumulation amount is less than or equal to a maximum value and an exhaust pressure difference is greater than a correction reference value, the ECU adds a correction value corresponding to the exhaust pressure difference to the estimated accumulation amount. Embodiments of the invention may also be configured to monitor and report temperature faults, power failures and other anomalies associated with the refrigerator or cold storage compartment.