The Battery Saver "All-in-one" is our Top of the Line 12 Volt 50 Watt Charger, Maintainer and Tester. The All-In-One combines our fastest charging technology, integrated micro-processor, automatic maintaining, automatic PULSE desulfator, modular cabling system and digital battery tester. The power benefit of the "All-In-One" is the ability to charge up to six batteries if they are connected together in parallel (multiple batteries. 12 Volt output.) This is perfect for vehicles that have more than one battery in a system, such as RVs or certain boats. The advanced computer control will monitor to make sure that no matter the size of the battery, it will be charged safely and efficiently. The modular cabling system is unique to our chargers and maintainers. We run longer lengths than anyone else and can accommodate nearly any cable length need. We offer 10' or 20' DC to DC extension cables for even the largest garages, as well as weatherproof enclosures to charge vehicles that are a long distance outside, away from a building. The built-in digital battery tester reads the voltage of the battery, the AMPERAGE power output of the charger and the power output of the vehicle's alternator. This can give you all the information you need to diagnose an issue with your vehicle's charging system, whether the fault lays with the battery or with the alternator.