Patent ID: 8264194

Claim:
A method, comprising: periodically sampling, by a processing circuit, a voltage of a power storage device; determining, by the processing circuit and at a first time, that the voltage is less than a turn on voltage; and in response to determining that the voltage is less than the turn on voltage; causing the power storage device to enter a charging state, the power storage device being charged by an environmental energy source while in the charging state; periodically sampling the voltage of the power storage device while the power storage device is in the charging state, the periodic sampling having a first sampling period that is less than an amount of time required for the voltage of the power storage device to increase from a turn off voltage to a maximum rated voltage of the power storage device, the turn off voltage being a voltage at which the power storage device is transitioned out of the charging state; and while in the charging state, causing the processing circuit to transition to a low power state between each periodic sample of the voltage.