You might call this model the big brother of the 17-3567. It offers some pretty amazing technology. For instance, its soft start feature will analyze a drained battery to determine if it is simply discharged or if it has one or more bad cells. If all checks out, the unit will then automatically begin charging at the full rate, which can be set at 2, 4 or 8 amps. In addition, it automatically compensates for variations in temperature, meaning that a battery in Duluth in January will receive the same, full charge as one in Death Valley in August -- safely. Its sophisticated software ensures that the new generation of gel and AGM batteries such as the Optima brand will receive a full charge. This unit can charge and maintain up to six batteries at a time. Highly recommended.