An intelligent battery to monitor battery states for an automotive use was newly developed. A main parameter to monitor battery states are based on the measurement of voltage variations that are to fluctuate immediately after an engine ignition. The developed monitoring unit is embedded into the lead-acid battery "CYBOX (R)" which does not have a current monitoring unit. The monitoring unit that has an alarm system which is compact and highly reliable essentially diagnoses the state of charge and the state of health of battery states in order to inform automotive user of the adequate timing of replace, recharge, and the hazardous state of overcharge of batteries. The battery-monitoring unit has an optical data transfer system to extract internal data from external device. The battery-monitoring unit also has a data acquisition instrument which receives more detailed monitored historical data from the optical data transfer system of the monitoring unit. (C) 2008 Elsevier B.V. All rights reserved.