Ask PYS: Power

Alan, on Jan 21, 2010 asked:

Can you provide guidance on how to best choose an inverter and charger for my Beneteau Oceanis 400? What should I consider?

Hi Alan,

Choosing an inverter and charger is very boater specific. Basically the choice you make depends on many factors, including your boat size, your boating habits, and your budget to name a few. Without more specific info we’ll provide you with some general principles on how we advise our own clients on selecting an inverter/charger best suited to their needs:

  1. Find out the wattage of the AC loads you want to run on the inverter. For instance, do you want to run a laptop, a microwave, a bread-maker, or even a hair dryer while away from the dock? You will also want to add a margin of error to your wattage calculation.  AC loads differ in their wattage and will ultimately influence the size (measured in watts) of the inverter you’ll choose.
  2. What type of loads are you planning to use? Some loads like bread-makers, blenders, and even DVD players are susceptible to modified (i.e. square) sine wave as opposed to a pure sine wave that you get in your home. If you are replacing an existing pure sine wave inverter, it would be best to make sure your new inverter is a pure sine wave inverter also. The only reason to choose a modified sine wave inverter is their reduced price.
  3. How quickly do you want to re-charge your batteries while connected to an AC source (e.g. how long will you be connected to shore power or how long do you want to run you generator)?
  4. Another limiting factor is your battery capacity. Battery loads and charging are limited by both your battery capacity (i.e. amp-hours) and the type of battery you have (i.e. gel, flooded, or AGM).
  5. Budget.

All these factors help us advise our clients on the best type of inverters/chargers for their needs. Our most popular models with our clients are the Magnum: MS 2000W & MS 2800W True Sine Wave inverter/charger.