Mercury - 24 Volt 175 Amp Alternator Heavy Duty Charging Series Marine Grade Construction 8M6007498. Overview. There is a special kind of comfort that comes when you glance at your gauges offshore and everything looks steady. Voltage is solid, lights are bright, electronics are clear, and you are not wondering if the batteries will still have enough in them when you hit the starter again. That is the quiet work a good alternator does for you all day long. You rarely see it, but you feel the diff