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MOSFET Regulator Rectifier for Harley Davidson Fat Boy 1580 & Heritage Softail 1584

MOSFET Regulator Rectifier for Harley Davidson Fat Boy 1580 & Heritage Softail 1584

SKU:RM30928

Regular price £111.30 GBP
Regular price £133.56 GBP Sale price £111.30 GBP
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Mosfet Voltage Regulator Rectifier RM30928 for Harley Davidson

Fat Boy 1580, Heritage Softail 1584 and Softail 1584 - 2007

Brand new Mosfet voltage rectifier regulator for the Harley Davidson Fat Boy 1580, Heritage Softail 1584 and Softail 1584. It is time to update or replace your voltage regulator with the advanced MOSFET type: it runs cooler than all OEM diode style regulators and has overheat protection, so rather than burn up it will simply turn off for a while and cool off. The unit is a direct replacement and installs plug-and-play with no rewiring.

MOSFET regulation brings real benefits on a big twin. It runs significantly cooler, reduces the load on the stator and so saves fuel, delivers regulated steady power to the battery which extends battery life and cold cranking capacity, frees engine power by removing stator load, and optimises power delivery by switching stator coils on and off rather than dumping excess energy as heat. This unit is built with a higher grade of electric components and an improved heat sink, the quality exceeds the OEM equipment, and all products are tested before shipment. It replaces Harley Davidson OEM part number 74540-07.

Key Features

  • MOSFET design, runs significantly cooler than OEM diode style units
  • Overheat protection - shuts off and cools instead of burning out
  • Direct replacement, plug-and-play installation
  • Reduces stator load, saving fuel and freeing engine power
  • Regulated steady power extends battery life and cold cranking
  • Improved heat sink and charging capabilities
  • Higher grade of electric components
  • Quality exceeds the OEM equipment, all units tested
  • Six wires at 200 mm, two plugs, 95 mm mounting centres

Technical Specs

Specification Detail
Part number RM30928
Type Mosfet voltage regulator rectifier
Width 90 mm
Length 130 mm
Height 40 mm
Wire length 200 mm
Mounting hole spacing 95 mm centre to centre
Number of plugs 2
Number of pins 5
Number of wires 6
Minimum charging voltage 14.5 V +/- 0.5 V
Maximum charging current 50 A / 500 W
Open circuit voltage < 15 V
Operating temperature range -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
Harley Davidson Fat Boy 1580 2007
Harley Davidson Heritage Softail 1584 2007
Harley Davidson Softail 1584 2007

OEM Part Number Cross Reference

Aftermarket replacement. OEM part numbers are listed for reference only.

Part Number Manufacturer / Brand
74540-07 Harley Davidson

Frequently Asked Questions

Does this fit without modification?

Yes. It is a direct replacement and fits plug-and-play. It carries six wires of 200 mm into two plugs with five pins, and the mounting holes are 95 mm apart centre to centre. Check that your original unit carries Harley Davidson number 74540-07 before ordering.

What is included?

The Mosfet voltage regulator rectifier with its fitted wiring and plugs. All products are tested before shipment.

How do I know my old regulator has failed?

Check the charge at the battery with the engine running: the system should hold 14.5 V +/- 0.5 V. A charge that never rises, or one that pushes past the 15 V open circuit figure, points to the regulator rectifier. Before fitting the new unit, check the AC output of the stator, replace burned or corroded connectors, repair any melted wiring and apply high temperature dielectric grease to all connectors.

What safety precautions apply?

There is a risk of electric shock, so disconnect the battery before servicing. Mount the unit where air can reach the heat sink, and torque the two 95 mm spaced fixings evenly so the case sits flat against its mount.

Dispatched from the UK · 12-month warranty · Fitment support from our technical team
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Shipping calculated at checkout. Free shipping over £150. Terms apply