Mercury - Alternator FourStroke, Verado & Racing Series Marine-Grade Steel 892940T02. Overview. Every boater knows that a healthy electrical system changes the entire feel of a day on the water. When the alternator is doing its job, everything works with that smooth, steady predictability you count on-the engine idles cleanly, electronics stay bright, and you never wonder whether the batteries will be ready when you head home at sunset. This Mercury Marine part brings that kind of assurance. It'