Automatically tests flat batteries for sulfated condition & if necessary applies a special high voltage (up to 22V) recovery action. Splashproof enclosure, SAE weatherproof connector, and wall mounts included. Optimate Three Plus features a 6-stage charging program with constant current. Recharges batteries discharged to as low as 2V even after a year of neglect. Interactive charging program reverts to bulk charge stage if required. Unique 30-minute timed charge verification stage ensures full charge. 30-minute timed check for excessive battery self-discharge. Complete automatic protections against every user error. Proven reliability (less than 0.3% warranty claims) & 2 years warranty.