The 601 is a battery capacity analyzer for testing 6V and 12V lead-acid batteries. It supports batteries with selectable capacities ranging from 1 to 100AH in 1AH steps and has a maximum input voltage of 20V. The analyzer displays the battery's stored charge as a percentage, shows both loaded and unloaded voltage, and can also measure internal resistance to identify defective or deteriorated units. It is an ideal tool for testing battery backup systems for emergency lighting, alarm systems, and UPS devices.