Nfc system providing battery power level measurement features and related methods

A Near Field Communication (NFC) system may include a battery including a battery casing, at least one battery cell carried by the battery casing, at least one power measurement circuit carried by the battery casing and configured to measure a power level of the at least one battery cell, and a first NFC circuit carried by the battery casing and configured to communicate the power level measurement via NFC communication. The NFC system may further include a mobile wireless communications device including a portable housing, a second NFC circuit carried by the portable housing, and a controller carried by the portable housing and configured to cause the second NFC circuit to receive the power level measurement from the first NFC circuit based upon proximity therewith.