Sealey Premier Battery Support Unit Charger & Maintainer 40A Features: Fully automatic 7-stage battery charger and maintainer, designed for charging a variety of EFB and AGM (stop/start), GEL, lead acid and calcium batteries with auto chemistry selection. Additional function to charge lithium batteries via selection button on front of unit. Zero volt battery charging, enabling recovery and charging of a completely discharged battery (providing any load removed from the rechargeable battery). Old battery sulfation repair function. 13.5V DC power supply for battery support function providing support for the battery during prolonged electronic diagnostic checks. Reverse polarity, short circuit, over temperature and overcharging protection. Built-in cooling fan that only operates when required. Intuitive LED screen displays charging voltage, current, battery capacity percentage, automatically selected 6V/12V or 24V charging, lithium charging mode, DC power supply mode and illuminated