JM open frame automatic battery charger is mostly used for charging engine starting batteries. The high-efficiency SCR controlled rectifier of this charger ensures high reliability and durability. The SCR phase control is used to regulate the output voltage at a constant level. This feature enables correct and accurate charging voltage to be measured, before connecting the battery to the charger. The JM open frame automatic battery charger will not operate if the battery terminals are connected in reverse. Normal operation resumes when the batteries are reconnected with the correct polarity across the charger terminals. This charger can be used to charge both, nickel-cadmium and lead-acid batteries.