Battery monitoring system, battery cartridge, battery package, and ridable machine

Provided is a battery monitoring system including a plurality of batteries (213) connected in series, a current/voltage measuring unit (214p) configured to measure an electric current and a voltage of a first battery in response to a measurement instruction, and a plurality of voltage measuring units (214s) configured to measure a voltage of a second battery (213) other than the first battery (213) in response to a measurement instruction. The voltage measuring units (214s) are connected to the current/voltage measuring unit (214p) with a daisy-chain connection by a communication interface, and the current/voltage measuring unit (214p) and the voltage measuring unit (214s) transfer the measurement instruction to another voltage measuring unit (214s) through the daisy-chain connection.