Articles, Catamaran Electrical Systems

Sailors in the North American market have become accustomed to the concept of having an inverter (a unit that takes DC battery power and “inverts” it into household AC power) and an AC-to-DC battery charger in one neat package. At first glance these combination (“combi”) units seem to have several main advantages over having a stand alone inverter and charger. With a combination inverter-charger there is only one piece of equipment to purchase and install, and the cost is typically lower than for separate stand alone units. Combi units also have an internal transfer switch that automatically shifts the AC loads on board to the new AC power source, thus avoiding conflicts between the inverter and the new power source.

Combination inverter-chargers currently on the market rely on transformer-based technology. This not only gives them the ability to serve as an inverter and a charger, but it allows them to have a relatively high “surge” capacity to satisfy short-term peak loads such as the start-up load for inductive AC electrical motors used in refrigerators, freezers, and pumps. Until recently, transformer-based inverter-chargers have dominated the market.

Inverter-chargers designed with transformer-based technology, however, are heavy and bulky, and in some ways they represent a compromise of performance in both the inverter and the charger mode of operation. Having a combination inverter-charger on board also means that if the unit becomes disabled and needs to be sent out for repair, both inverter and charger are out of operation.

Many multihull sailors are becoming intrigued with the new generation of stand alone inverters and chargers on the market, especially those from Mastervolt, a Dutch company known for its high quality power electronics equipment. Mastervolt is now bringing their products and their concept of a full-service dealer network to the North American market, with a point of entry and warehouse facility in Thomaston, Maine and a distribution center in Ft. Lauderdale, Florida.

I recently visited the Mastervolt head office in Amsterdam, and was impressed with their apparent commitment to quality and product engineering. But what really was impressive was their manufacturing facility near the German border. All electronics manufacturing is subcontracted to a specialized production company called NEDAP. Touring the NEDAP facility was more like visiting a museum or art gallery than a corporate production plant. Every aspect of the facility was beautiful, including the machining, soldering, and assembly lines. A towering glass wall allowed natural light into the work areas, and beyond the wall was a garden with water pools and benches for enjoying breaks and lunch outside. It reminded me of the ancient Greeks, who apparently had only one word for art and technology, since these two concepts were inseparable in their minds.

The entire line of Mastervolt inverters have pure sine wave output (same as household or dockside power), as opposed to the majority of inverters on the market which are designed with a stepped, modified sine wave output. While modified sine wave output works well for almost all appliances, pure sine wave technology is rapidly becoming the industry standard. Traditionally, the two drawbacks to sine wave inverters were higher cost and lower efficiency. Although the price is still quite high, Mastervolt has created a very efficient, solidly built line of stand alone sine wave inverters that are also lightweight due to the use of switch-mode instead of transformer-based technology. Weight is such an important consideration on a multihull that this type of system is worth investigating. An installation using a stand alone Mastervolt inverter and battery charger will be roughly half the weight of a combination inverter-charger using transformer-based technology. Mastervolt MASS stand alone sine wave inverters come in a wide range of power ratings, from 250 watts to 2500 watts in both 12 and 24 volts, and in North American power output (117V/60HZ) and European standard power output (230V/50HZ).

The Mastervolt MASS stand alone battery chargers have their own impressive characteristics. Like the MASS inverters, they are designed with switch-mode technology which allows them to be lightweight, yet they are also very efficient and robust. They all have high performance 3-stage charging characteristics with inherent battery protection, and 2 or 3 outputs including a small 3A circuit for a starting battery. But the main advantage of MASS chargers is that the European models can tolerate input power within a range of 180-265 volts and either 50 or 60HZ frequency. This means they can operate equally well on European dockside power or on a North American 220 volt circuit, a great feature for world cruising. MASS chargers come in 30 to 100 amp ratings, in either 12 or 24 volt output. IVO Smart Chargers from Mastervolt are another alternative for stand alone applications. Models that can tolerate between 90-265 volt and 50-60HZ input are available in 25 and 40 amp ratings for 12 volt, and 15 amp rating for 24 volt operation.

Mastervolt is a system oriented company. In Europe they offer a complete line of products to create fully integrated systems. In the North American market they are cautiously offering only their core products at this point. A typical Mastervolt stand alone system for a cruising multihull might include:

a MASS 12V/2000W, 117V/60HZ sine wave inverter
a MASS 12V/60A 180-265V/50-60HZ battery charger
a stand alone manual or automatic transfer switch
a Mastervolt BTM 1 system monitor with secondary monitoring of a starting battery

The cost of Mastervolt equipment is quite high compared to other electrical power gear on the market, but the quality, appearance, efficiency and flexibility make it well worth considering when upgrading or installing a new system.


About the Author

Independent Energy Guide Kevin Jeffrey is a long-time multihull sailor, independent energy consultant, author and book publisher. He is the author of Independent Energy Guide, a valuable resource for cruising mutihull sailors, and is the publisher of Adventuring With Children by Nan Jeffrey and the first three editions of the Sailor’s Multihull Guide. Sailors Multihull Guide