This is a brand new aftermarket rectifier for 1967-2000 Mercury outboard engines from 7.5 HP up to 300 HP. It is a direct replacement for the original unit, plug-and-play and direct fit, with no assembly required. Part number RM30433 replaces Mercury OEM 332-2910 and the full list of superseded numbers shown in the cross reference table below, including 816770T and 8M0058226.
The rectifier is what turns the alternating current produced by the flywheel charging coils into the direct current the battery can actually store. Without it the battery simply will not take a charge, however healthy the stator is. This is a compact square unit, 38 mm by 38 mm by 22 mm, with its two fixing holes 38 mm centre to centre, so it drops straight onto the original mounting pattern. It is built from a higher grade of electric components than the original, holds a minimum charging voltage of 14.5 V +/- 0.5 V, is rated to a maximum charging current of 20 A / 150 W with an open circuit voltage below 15 V, and is designed to operate from -20 C to 85 C. Connectors are supplied with the part, and every unit is tested before it is shipped.
Key Features
- Brand new aftermarket rectifier
- Direct replacement to your original unit
- Plug-and-play, direct fit, easy installation
- No assembly required
- Higher grade of electric components
- Quality exceeds the OEM equipment
- Connectors included with the part
- All products shipped are tested
Technical Specs
| Specification |
Detail |
| Part Number |
RM30433 |
| Width |
38 mm |
| Length |
38 mm |
| Height |
22 mm |
| Fixation Holes Centre to Centre |
38 mm |
| Minimum Charging Voltage |
14.5 V +/- 0.5 V |
| Maximum Charging Current |
20 A / 150 W |
| Open Circuit Voltage |
Below 15 V |
| Operation Temperature |
-20 C to 85 C |
Vehicle Fitment Guide
Years shown are the overall coverage span for this part. Please confirm against the OEM part number on your original unit before ordering.
| Make & Model |
Years |
| Mercury Outboard 7.5-300 HP models |
1967-2000 |
OEM Part Number Cross Reference
Aftermarket replacement. OEM part numbers are listed for reference only.
| Part Number |
Manufacturer / Brand |
| 332-2910 |
Mercury |
| 332-2910A1 |
Mercury |
| 332-2910A2 |
Mercury |
| 332-2910A3 |
Mercury |
| 62351A1 |
Mercury |
| 62351A2 |
Mercury |
| 78614A1 |
Mercury |
| 816770 |
Mercury |
| 816770T |
Mercury |
| 8M0058226 |
Mercury |
Frequently Asked Questions
Will it fit without modification?
Yes. The body is 38 mm square and the two fixing holes are 38 mm centre to centre, matching the original mounting pattern, so it bolts straight on. The engine range is wide, so the safest check is the number on the unit you are removing - if it is any of the numbers in the cross reference table, this is the right part.
What is included?
One brand new rectifier, part number RM30433, supplied with its connectors. Mounting hardware is not included, so reuse the original screws and any earth strap or star washer that came off with the old unit - the rectifier relies on a clean earth to work properly.
How do I know the old rectifier has failed?
Measure the voltage at the battery with the engine running and the revs raised slightly. If it does not lift above resting battery voltage, and the stator itself tests within spec, the rectifier is the usual culprit. A battery that is flat again after every outing, despite hours of running, is the classic complaint on these engines.
My engine is a 1970s model - is this still correct?
Mercury used this rectifier across a long production run, which is why the coverage spans 1967 to 2000 and 7.5 HP through 300 HP. Because the span is so broad, always confirm the OEM number stamped on your original rather than relying on horsepower alone. Our technical team can check it for you if the number is no longer readable.
Dispatched from the UK · 12-month warranty · Fitment support from our technical team
