Mosfet Voltage Regulator for Harley-Davidson Softail, Fat Boy & Heritage 2001-2006
Mosfet Voltage Regulator for Harley-Davidson Softail, Fat Boy & Heritage 2001-2006
SKU:RM30312
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Mosfet Voltage Regulator for Harley-Davidson Softail
Screaming Eagle, Fat Boy, Heritage Softail and Softail Deuce - 2001-2006
A brand new Mosfet voltage rectifier regulator, part number RM30312, built to replace the OEM diode style regulator fitted to Harley-Davidson Screaming Eagle, Fat Boy, Heritage Softail and Softail Deuce models from 2001 to 2006. Installation is plug and play - the unit uses the original style connector, so it goes on in place of the factory part with no rewiring.
The difference between this unit and the original is the switching technology. A conventional diode or shunt regulator gets rid of the stator output it does not need by turning it into heat, which is why the factory regulators run so hot and why they take the stator with them when they fail. A Mosfet regulator switches instead of dumping, so it runs considerably cooler, puts less load on the stator, delivers cleaner regulated energy to the battery and returns a little more of the engine's output to driving the bike rather than to heat. This unit also has an improved heat sink and built in overheat protection: if it does get too hot it shuts itself off temporarily and recovers, rather than burning up.
Key Features
- Mosfet technology - switches rather than dumping excess energy as heat
- Direct replacement for the OEM diode style regulator
- Plug and play installation, no rewiring needed
- Improved heat sink for cooler running
- Overheat protection shuts the unit off temporarily instead of letting it burn up
- Reduced load on the stator, which also helps fuel consumption
- Cleaner regulated output, which extends battery life
- Superior grade electrical components throughout
- Dispatched from the UK with technical fitment support
Technical Specs
| Specification | Detail |
|---|---|
| SKU / Part Code | RM30312 |
| Component | Mosfet Voltage Regulator Rectifier |
| Width | 44 mm |
| Length | 87 mm |
| Height | 132 mm |
| Wire lengths | 1013 mm and 170 mm |
| Distance between fixation holes (centre to centre) | 100 mm |
| Number of plugs | 1 |
| Number of pins | 3 |
| Number of wires | 5 |
| Minimum charging voltage | 14.5 V +/- 0.5 V |
| Maximum charging current | 50 A / 500 W |
| Open circuit voltage | Under 15 V |
| Operating temperature | -20 C to 85 C |
| Condition | New aftermarket |
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 |
|---|---|
| Harley-Davidson Screaming Eagle | 2001-2006 |
| Harley-Davidson Fat Boy | 2001-2006 |
| Harley-Davidson Heritage Softail | 2001-2006 |
| Harley-Davidson Softail Deuce | 2001-2006 |
OEM Part Number Cross Reference
Aftermarket replacement. OEM part numbers are listed for reference only.
| Part Number | Manufacturer / Brand |
|---|---|
| 74610-01 | Harley-Davidson |
| 74540-01 | Harley-Davidson |
Frequently Asked Questions
Does fitting it need any modification?
No. On the models listed above it replaces the OEM diode style regulator directly and installs plug and play. Check the 100 mm centre to centre mounting hole spacing and the 1013 mm and 170 mm wire lengths against your bike before you order, so you know the leads reach where they need to.
What is included?
The Mosfet regulator unit itself, with one three pin plug and five wires as listed in the specification table. It measures 87 mm long by 44 mm wide by 132 mm high, so you can compare it against the part you are removing.
How do I tell whether the old regulator has failed?
Measure the battery voltage with the engine running and warm. A working charging system holds around 14 to 14.5 volts. A reading stuck at battery voltage means no charge is getting through, and a reading well above 15 volts means the regulator has lost control and is overcharging - that is what boils batteries and blows bulbs. Test the stator and the earth connections at the same time, so you do not replace a good regulator.
Why choose Mosfet over the standard diode regulator?
A diode regulator disposes of surplus stator output as heat, so it is always running hot and it keeps the stator working at full load. A Mosfet unit switches instead, which means cooler running, less stress on the stator, more stable regulated output for the battery and slightly less parasitic drag on the engine. This one is rated at 50 A / 500 W maximum charging current with a minimum charging voltage of 14.5 V plus or minus 0.5 V, and it also carries overheat protection that shuts it down temporarily rather than letting it destroy itself.
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