The ARCO Replacement Alternator for Mercury 75-115 HP outboards is a 12V 50A unit with a four-groove pulley and internal fan.
The horsepower range is the fitment guide, and 75 to 115 HP is a specific band within Mercury’s outboard line. The 135 to 150 HP version is a different alternator at a higher output, so matching the engine rather than the brand is what gets the right part.
Fifty amps is the charging output for this engine range, and it reflects what the outboard was built to supply. Fitting a higher-output alternator is not a free upgrade on an outboard, since the belt, mounting and engine all suit the original rating.
The four-groove pulley and internal fan come fitted, so the unit installs without transferring parts from the old alternator. That saves a puller and a press, and avoids the pulley that will not come off intact after years of service. Explore more marine alternators.
- 75-115 HP is a specific band in Mercury’s line
- The 135-150 HP version is a different alternator
- 50A matches what the outboard was built to supply
- Pulley and fan fitted, so nothing transfers over
