SunGuard Solar Regulator 4.5A Solar charge controllers or regulators are recommend to avoid battery damage from overcharging or deep discharge. The Morningstar SunGuard regulator is designed for simplicity of installation and can be used with gel, AGM (absorbed glass matt), sealed and non-sealed lead acid batteries.The SunGuard uses an advanced series PWM (pulse width modulation) charge control for constant voltage charging. A true 0 to 100% PWM cycle is very fast and stable, ideal for efficient battery charging.,100% solid state design using MOSFETs rather than mechanical relays. The unit can be mounted inside or out as the cables covered in Hypalon insulation.