Alternator chargers put every ounce of power to good use. While on the water they take your alternator s excess power and redistribute it to your trolling batteries. You get an extra boost and better battery life. Charge-on-the-fly: After the boat s alternator has fully charged the starting battery this technology will reroute the alternator power to the trolling motor batteries. Battery Protection: extends battery life by protecting your battery from frequent deep discharges. LED Indicator Lights: Inform of charge stage maintenance mode status error notifications and full charge. Waterproof Construction: All on-board chargers are built to be waterproof shock-resistant and vibration-resistant. 3-Year Warranty: All battery chargers come with a full 3-year replacement warranty.