3D0959831D 20H Volkswagen BUTTON FOR

The BUTTON FOR from Volkswagen (MPN: 3D0959831D 20H) has supplier-listed dimensions of 30 x 30 x 55 mm. It is typically used within the Electrical & Lighting > Power Supply > Alternator category of automotive replacement parts. Dimensions are provided by the supplier and may include packaging dimensions. Alternators are rotating electrical generators converting mechanical energy from the engine’s crankshaft into electrical energy. Typically engine-mounted and belt-driven, they supply power for vehicle electrical systems and recharge the battery. Output is regulated via an internal voltage regulator to maintain a consistent voltage, typically 13.5-14.5V. Core components include the rotor, stator, rectifier diodes, and regulator, all housed within a sealed unit. Modern alternators frequently utilize a serpentine belt drive and may incorporate one-wire or high-output modifications for specialized applications.