2006-2010 Suzuki DF150 / DF175 4-Stroke Outboards Service Manual, Page 140Get this manual
ENGINE ELECTRICAL
ISOLATOR FUNCTION The battery charging system is equipped with an isolator functionWhen sub battery is used in addition to the main battery for engine operation, this function allows both the batteries to be charged at the same timeTo modify the charging circuit and distribute the power to the individual batteries, relocate the 30 amp fuse in [STD] position to [OPT x] position in the fuse boxRelocation of the 30 amp fuse to [OPT x] position modifies the charging circuit so the No.2 red output lead of the RectifierRegulator can charge the main battery for engine operation and the No.1 red output lead can charge the sub batteryNOTE: For proper charging circuit operation, the negative terminals of both batteries, main and sub batteries, must be connected with cable of the same size as the existing battery cable