Nvis 455 is a 6A solar charge controllers and Nvis 455A is a microcontroller based 10A solar charge controllers. These charge controllers are designed to monitor the battery voltage during charging and discharging. It disconnects the solar panel when battery is fully charged and disconnects the load when battery is discharged up to a predefined voltage. It again connects the solar panel when battery voltage decreases, and connects the load when battery voltage increases. This product will provide a long life to your battery.