The CTEK DC/DC Onboard Charging Solution, featuring the D250SE and Smartpass 120S, provides a powerful 140A charging capability for a RV or commercial vehicle battery. The D250SE, a fully automatic five-step charger, draws power from the vehicle alternator to deliver 20A of power to charge, condition, and maintain any 12V service battery whilst on the move. The Smartpass 120S, a fully automatic 120A power management system, distributes power between the starter battery, the service battery, and onboard equipment without the need for traditional diodes or VSR relays. CTEK’s onboard charging solution is smart alternator compatible and operates even when there is low alternator output. Charge can be prioritized allowing critical functions like starters, radios, emergency lights, and communication systems to have power over non-critical functions.