New MOSFET 20 Amp Voltage Rectifier Regulator

Author: Tri-Spark   Date Posted:27 November 2019 

We are pleased to let you know we have developed a premium voltage regulator with the latest MOSFET technology.

Now you can replace those ageing Lucas components on your bikes charging system with the MOSFET 20 Amp Voltage Rectifier Regulator. Get improved power output, less heating and better reliability.

These voltage regulators use MOSFET technology for cool running reliability. Unlike the previous generation of regulators that waste power and run hot.

Our MOSFET Voltage Rectifier Regulator has many benefits:

  • Generous 20 amp rating exceeds the requirements of 10 amp, 16 amp and 14.5 amp two and three wire stators commonly used on British bikes
  • High output power with low temperature
  • Fast voltage recovery - low battery
  • Heavier wire connections are extra long (60 cm) in two sleeves so you can route the wires and connect them exactly as you wish.


Size is 80 x 67 x 20 mm. Mounting hole centres 64mm

Here are two thermal images of voltage regulators operating; picture one is of a well known voltage regulator on the market, picture two is the MOSFET Regulator. As you can see the temperature is a lot less.

Picture one Picture two


Smaller in size makes fitting possible in tight locations under the seat or behind side panels. Cool running so you can hide it away!

Why muck around with hot unreliable regulators that waste over 20 watts of precious power when you can have the latest!

Suitable for use with 2 and 3 wire stators (single and three phase). 10 amp single phase, 16 amp single phase and 14.5 amp three phase. These stators are commonly known as RM21, RM23 and RM24 used on Triumph, Norton, BSA , Enfield, Matchless etc...compatible with any single or three phase permanent magnet 12 volt alternator up to 20 amps.

Whether you are replacing the original equipment plate rectifier and zener diode or upgrading an older regulator. this one will tick all the boxes!

Complete with wiring instructions and covered by a 2 year warranty. This is a high quality solution for your classic bike's charging problems.

See our video comparing conventional diode voltage regulator with the MOSFET voltage regulator.


Comments (1)

Full voltage at tick over

By: on 21 April 2020
The fitting instructions are easy to follow. I got 14.39 volts at tick over, this was measured on the old ancillary socket on the MK3 live terminal and timing cover - which still has the original wiring. When revved the voltage remained stable, within 0.1V. After fitting, I rode out in 5C temperatures, with my LED sidelight on it and the regulator never even got warm. The Al Osborn BSM (battery status monitor) showed green all the way. On the return, I rode with my 30W headlight on and the BSM still showed green, the only time it showed red was when stopped at traffic lights, brake on and indicator on. When I got home after 17 miles it was just about detectable with a cold finger as being lukewarm. Riding with the 30W LED headlamp on, morning and evening does not affect the battery, it starts on the electric starter just fine, so the battery is staying topped up even with continual dark hours riding. I have also checked the temperature a few times after riding with all lights on and it does not even get that warm – you can keep your hand on it. And that is with original wiring!!

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