Alternators & Charge Regulators

The existing alternators on engine are designed to charge the starter battery. As a result the combination is not ideal for fast and full charging of other batteries, especially if you want to charge the batteries over a short time or when powering a heavy load.

There are two options to solve this issue:

Equip the standard alternator with a Mastervolt Alpha Pro charge regulator. This charge regulator maximises the output of alternators by regulating the alternator in a way that ensures that batteries receive the optimum charge. The proven 3-step+ charge method guarantees fast and safe charging of your batteries.

You can also choose a powerful second Mastervolt Alpha alternator with Alpha Pro charge regulator. This combination was specifically designed for charging service batteries, and allows you to charge quickly and turn off your engine when you want. 

Alpha Pro charge regulators

  • Suitable for 12 and 24 V.
  • Including plug & play connection cable, an adapter cable for Bosch alternators is optional.
  • The Alpha Pro series is suitable for most alternators with a charging current of up to 400 amps.
  • Automatic voltage and temperature compensation.
  •  ‘Keep alive’ function for tachometer.
  • MasterBus compatible.

The charge regulator measures the battery temperature and adjusts the charging process accordingly, resulting in a safe and fast charge. Therefore the battery is always kept in good condition.

Alpha alternator series

  • Fast & complete charging of starter and service batteries.
  • Power supply for all consumers.
  • 12 V and 24 V versions.
  • 75 A to 150 A charge current.
  • Standard delivered with Alpha Pro MB charge regulator for an optimal performance and longer-lasting batteries.

Using a Battery Mate or battery isolator in conjunction with an Alpha alternator makes it possible to easily charge two or three separate battery sets simultaneously.

12 Volt / 24 Volt DC Alternators

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48 Volt DC Generator / Alternator

DC Generator / Alternator

AC Delco - 24 Volt Generator Converted to 48 Volts DC for Off-Grid Applications.

This is a "one of a kind" demo unit AURORA received and has not been used. 


    $ 290.00 USD $ 424.00 USD
    More Info

    Alternator Regulator 12/24 Volts | Alpha Pro III

    The new Alpha Pro III charge regulator from Mastervolt transforms any alternator into an advanced 3-step battery charger


    Not all alternators have been optimized for efficient battery charging, but the new Alpha Pro III charge regulator will change all that. Compatible with any alternator or battery type, it will greatly boost your boat’s charging ability.

    Mastervolt, the Dutch based leader in off-grid electrical systems, is proud to announce the arrival of the Alpha Pro III, an advanced, temperature-controlled charge regulator that will greatly enhance the efficiency of any type of marine alternator. The new charge regulator not only provides a three-step charging process, the most efficient and safest regime available, it also monitors the engine load to help reduce engine noise, and wear and tear on the alternator’s components.

    The Alpha Pro III is an intelligent charge regulator, and if required can communicate with the rest of the electrical system via the MasterBus data cable. The electronics provides a smart ‘keep alive’ feature ensures reliable tachometer readings. Using MasterBus, the charge regulator communicates RPM, alternator status and charge status to the rest of the electrical system, all of which can be automated or controlled via an EasyView 5 touch screen.

    Maximize your alternator

    Many boats are fitted with a standard alternator, a low-cost unit that will only charge the batteries relatively slowly. They can also easily overheat, which further impairs charging efficiency. By replacing the standard charge regulator with an Alpha Pro III, a boat owner will access a much faster charge cycle along with protection for the batteries against overheating and overcharging. Combined with the three-step charging process, these safeguards will greatly extend the lifespan of the battery bank.

    Even greater efficiency

    For super fast charging at low RPM, Mastervolt recommends to combine the Alpha Pro III with a high performance alternator such as the reputable Alpha series. With 20 amps of field current capability, the Alpha Pro is the only 3-step regulator in the market capable of controlling alternators with outputs up to 400 A!

    Designed for easy installation, the Alpha Pro III is the distillation of 20 years of Mastervolt’s experience in providing fast, reliable charging that protects your batteries whilst maximizing their efficiency and lifespan.

    Key features:

    • Transforms any alternator into a 3-step charger with full temperature control.
    • Protects from overcharging for greater battery life.
    • Lowers engine noise and emissions, and saves fuel.
    • Balances engine load to smooth out RPM variations.
    • Compatible with most alternators, including performance 200 A - 400 A models.
    • Integrated ‘keep alive’ feature for reliable tachometer readings.
    • Suitable for every type of battery chemistry, including Li-Ion.
    • Works with both 12 V and 24 V systems.
    • MasterBus compatible for intelligent system monitoring and automation.
    • Easy installation.

    Note: Replacing a standard alternator charge regulator is not allowed on Euro 5/6 engines.

    Technical Specifications:

    • Model: Alpha Pro III.
    • Dimensions: 90 x 109 x 30 mm.
    • Weight: 0.4 kg.
    • Output voltage: 12 V / 24 V selectable.
    • Alternator types: negative excitation up to 20 A field current.
    • Battery types: all types, including Lithium Ion.
    • Bulk/Absorption/Float voltage: AGM, Gel and Lithium Ion pre-sets/adjustable.
    • Absorption time: 4 hours, adjustable from 0 minutes to 10 hours.
    • Voltage drop compensation: up to 3 V.
    • Delivered with: battery temperature sensor with 6 m of cable

    download pdf     product news


    General specifications
    Link to MasterShunt yes
    Connection to Mastervolt alternator yes
    Connection to Bosch alternator yes, using a Bosch adapter cable (product code 45510500)
    Nominal battery voltage 12 V / 24 V
    Cable length regulator/alternator 1.5 mtr / 5 ft oil resistant connection cable
    Connection plug regulator/alternator Alpha/Mastervolt
    Cooling fanless
    MasterBus powering yes
    Display/read-out LED display
    Dimensions, hxwxd 90 x 109 x 30 mm
    3.5 x 4.3 x 1.2 inch
    Weight 0.4 kg
    0.9 lb
    Delivered with battery temperature sensor with 6 m (20 ft) cable
    Approvals CE
    Technical specifications
    Charge characteristic IUoUo, automatic / 3-step+ for Gel/AGM/flooded/Lithium Ion
    Charge voltage Bulk/Absorption/Float default setting for AGM, Gel and Lithium Ion (adjustable)
    Absorption time 4 hours, adjustable from 2 minutes to 12 hours
    Temperature compensation -30 mV / °C
    -17 mV/ °F
    DC voltage compensation voltage drop compensation in DC cables up to 3 V
    Alternator type alternators with negative excitation
    Field currents up to 20 amps
    MasterBus compatible yes

      $ 399.00 USD
      More Info

      Alpha 12/130 MB | Alternator and Battery Charge Regulator

      Alpha 12/130 MB

      Delivery includes Alpha Pro MB charge regulator.


      • Fast & complete charging of starter and service batteries.
      • Power supply for all consumers.
      • 12 V and 24 V versions.
      • 75 A to 150 A charge current.
      • Standard delivered with Alpha Pro MB charge regulator for an optimal performance and longer-lasting batteries.

      Using a Battery Mate or battery isolator in conjunction with an Alpha alternator makes it possible to easily charge two or three separate battery sets simultaneously.

      TIP: A second alternator on the main engine, combined with a larger battery bank and inverter, could be an alternative for a generator.

      For all engine types

      Alpha alternators are equipped with several fixations for customised alternator brackets, available from your installer or engine supplier. Some engine brands come with Mastervolt alternator brackets as an option.

      Fast charging, even at a stationary rpm

      Standard alternators only supply the specified capacity at a high rpm. The Mastervolt Alpha alternator is specifically designed for powerful charging, even with a low engine rpm.

      Multigroove pulley

      The 12/130 and 24/75 models are also available with a multigroove pulley.

      Performs above 40 °C

      Forced cooling by fan operation of the pulley provides a lot of power in higher temperatures, especially close to the engine.

        $ 1,477.02 USD
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        12 Volt / 120 Amp | DC Alternator

        Alpha Compact 14/120

        Delivery includes Alpha Pro III charge regulator.


        Alpha Compact alternators are optimized to deliver continuous high power output in energy storage applications. Combined with our Alpha Pro regulators, they create a high performance, plug-and-play charging solution. This combination is suitable for all battery types, including Lithium Ion.

        These automotive style alternators offer many advantages. Most manufacturers offer a second alternator option, better known as PTO or Power Take Off option. This provides a straight-forward way to add an Alpha Compact as a second alternator. Alternatively, the stock alternator can be replaced with an Alpha Compact to obtain a powerful 3-step charger.

        High performance plug & play alternators

        Compared to conventional alternators, Alpha Compact offers lower weight, smaller dimensions and reduced fuel consumption. This is made possible by its open construction with double internal fans. An integrated temperature sensor controls the operating temperature.


        The Alpha Compact series consists of 4 models in 12 V and 24 V. Special models for Volvo Penta engines are under development. Finding the right alternator for a specific application can be complicated. Please feel free to contact Mastervolt for assistance, we are happy to help you.


        Freewheeling multigroove pulleys are available in various diameters and widths for an optimal pulley ratio and belt alignment. Exception to the rule is the Alpha Compact 14/200, which comes with a multigroove pulley as standard.

        Isolation bushings - the negative pole of Alpha Compact alternators connects to the housing. Isolated operation is possible by installation of isolating bushings.

        Modern Euro 5/6 engines include an auto start/stop system. Multiple solutions are available to detect a running engine.


        Worldwide use in marine, mobile, infrastructure and industrial applications.


        • Plug and play solution, with Alpha Pro III regulator included.
        • Up to 40 % lighter and 25 % more compact than conventional alternators.
        • Up to 40 % lower fuel consumption.
        • OEM quality with optimized material composition.
        • Suitable for use in high temperature areas.
        • Cable and electronic parts protected against oil, moisture and dust.
        • Engine RPM signal.
        • Wide range of accessories available.
        • Easy installation.
        • Full 2 year warranty.


        General specifications
        Charge regulation an Alpha Pro III charge regulator comes standard with all models
        Isolated operation yes, with optional isolation bushings
        Rotational direction clockwise
        Galvanic isolation non-isolated
        Cooling integrated dual fan
        Mounting swivel arm
        Pulley included no
        Weight 6.7 kg
        14.8 lb
        Technical specifications
        System voltage 12 V
        Nominal current (at 6000 rpm, 25 °C) 120 A
        Charge current (at 1800 rpm, 25 °C) 70 A
        Cut-in speed 1300 rpm
        Max. rotational speed 20.000 rpm
        Power Take Off (kW / hp) 3,4 / 4,5
        Max. operating temperature 110 °C
        230 °F
        Connections positive output stud = 2x M8; W (rpm) signal connection = isolated fast-on; field current connection = Mastervolt plug
        Temperature sensor integrated, RJ12 connection

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