Battery Tender Battery Charger - Selectable - Charge and maintain up to two batteries simultaneously with the rugged, water-resistant two-bank battery charger. Battery Tender multibank chargers are uniquely designed to charge each bank independently, regardless of battery chemistry. Automatically switches from full charge mode to float charge mode for optimal long-term battery health. Compatible with all 12V lead-acid, flooded, AGM, and gel cell batteries and lithium batteries. 4-step charging algorithm optimizes battery life while preventing overcharging or discharging. IP67 and Marine UL ratings for weather, shock, and vibration resistance. Safety features including spark-proof, reverse charging warning, and ignition protection. Marine-grade fused battery quick disconnects. Battery Tender battery chargers are completely automatic and may be left connected to both AC power and to the batteries being charged for long periods of time