CTEK Smartpass 120S 120A Power Management System for 12V Starter Service BatterySmartpass 120S charges and supplies the service battery and equipment with 120A, separates critical equipment from non critical equipment ensuring that radio, emergency lights and navigation systems always have power. Smartpass 120S is a 120A Power Management Solution which distributes, controls and maximises the available energy from your alternator to power service batteries and consumers. SMARTPASS 120S handles all 12V batteries between 28 800Ah.