Mercury Mariner 30/40 4-Stroke Outboard Service Manual 1998, Page 91Get this manual
CHARGING" STARTING SYSTEM
Battery Charging System
Description (15 Ampere)
The battery charging system components are the stator battery charge coils, regulator and batteryAlternating current (generated in battery charge coils) flows to the regulator, which changes the alternating current to regulated direct current for charging the battery