Microcontroller Based Online Health Monitor tests health condition of a lead-acid cell of a battery bank without requirement of disconnecting the cell from the bank and also without disconnecting the charger. The Online Health Monitor is programmed to do the test automatically by setting the various test parameters as per the type of cell. The Online Health Monitor is a microcontroller based instrument that ensures optimum performance for longer period of time. Microcontroller Based Online Health Monitor can be availed in different specifications to cater to specific requirement.