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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.

Maximise 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 superfast 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.