Mercury - Alternator Volvo-Penta Sterndrive Series Corrosion-Resistant Marine Finish 8M6007493. Overview. Anyone who spends time on the water knows how quickly a perfect day can shift when your electrical system stops keeping up. You hear it first-the hesitation when you crank the engine, the dimming of a chartplotter, the uneasy feeling that tells you something isn't charging the way it should. Out there, reliability isn't just convenient; it's essential. That's why boaters trust Mercury Marine