We can always gauge what is going on in the market place by the conversations we are having with fellow boat owners. One topic that has been coming up a lot lately, involves older modified sine-wave inverter/chargers, like the popular Freedom line, failing. And they aren’t failing at the dock, they are failing while in use, in the middle of the vacation. It’s to be expected, these units are now 10 to 20 years old. An inverter/charger is a sophisticated piece of technology and, like other pieces of onboard electronics, are not made to run forever. These units don’t last forever, so avoid problems next cruising season by replacing your inverter this winter.
Losing an Inverter vs. Losing an Inverter/Charger. Losing the benefits of an inverter while on the water will vary from boater to boater. Many boaters only use the inverter to run convenience items like a TV or microwave while away from shore-power. If your inverter fails, you can make do without it. However, for many boaters, the inverter is critical as it runs the fridge while away from shore-power or without the genset running. As well, many inverters also come with a charger, often referred to as an inverter/charger. While losing the inverter functionality will vary from boater to boater, losing the charger for the house batteries will most likely curtail a cruise for most boaters. A battery charger is essential to recharge the battery bank while at the dock and to offset the DC loads while on shore-power or running the genset to ensure that the batteries are not depleted. Without a charger, the only means of charging the batteries is via the alternators. This is fine if you are moving and going to new spots constantly, but what if you want to be at the dock or run the genset to recharge the batteries. Very quickly you will find yourself with depleted batteries and limited ways of recharging them.
Another difference between old and new technology, is the efficiency. An older Freedom inverter/charger offered abouttwo thirds efficiency, the new units are 90 percent plus. For those who use inverters a lot, this will translate to significant power savings on your batteries and less draw provides a longer time between charges or a shorter charging time.
Modified or Pure/True Sine. As we have mentioned in prior articles, there are two main types of inverters, modified and pure or true sine. Many boaters still have modified sine wave inverters on their boats and they work well for most resistive loads, such as lights and coffee pots, but have a hard time running any inductive loads, such as microwaves, TVs, and even modern coffee machines. Modified sine wave inverters used to be the most common and are the least expensive. Pure sine wave can handle all AC loads and are specifically good at handling AC inductive loads such as laptops, battery chargers for cordless tools, dimmers, sanders, polishers and stereos. Pure sine wave inverters produce a better, cleaner power, identical to that in your house. The price difference between modified and pure sine wave has narrowed and, considering the benefits, most boat owners are choosing pure sine wave inverters.
If you have a modified sine wave inverter of any age or a pure sine wave inverter that is over 10-15 years old, it may be time for an upgrade. So what should you consider when choosing a new inverter/charger? The first thing to take into account is the size of your existing battery bank. The challenge is matching your house bank, measured in amp-hours, to the inverter rating measured in watts. As a rule of thumb, we recommend a battery bank with a capacity sized at 20 percent of wattage. For instance, a 2,000-watt inverter should be connected to a 400 amp-hour battery bank. Inverters are available in all sizes, but the most popular choice is between 2000 to 3000 watts.
How To Size A Charger. Next, calculate the draw or maximum concurrent AC loads you will run. Then decide the output of the charger, the larger the inverter wattage rating the larger the charger output. For instance, a 2000-watt inverter will provide a 100-amp charger at 12 VDC and a 3000-watt inverter will provide a 150 amp charger at 12 VDC. Depending on your battery size, you will want to have a charger that is at least 10 percent of battery capacity. With flooded lead acid batteries you can comfortably go to 20 percent of capacity. For instance, eight flooded golf carts in a 12 VDC bank will provide 880 amp-hours of capacity. With the minimum charge rate of 10 percent, the charger for this bank should be at least 88 amps.
Also remember, there are some high wattage loads that should not be run on the inverter such as a water heater, air conditioner, electric range or space heater. If you are using these items, you will need a generator or be connected to shore-power.
The next thing to consider is reliability. We have had great success with brands such as Magnum, Mastervolt and Victron. If you are looking at installing a new 2000 to 3000-watt inverter/charger, we would recommend models such as the Magnum MS Series, the Mastervolt PowerCharger/ChargeMaster or the Victron MultiPlus. Check with your retailer but most of these units come with a two- to five-year warranty. Victron, founded in 1975, and Mastervolt, founded in 1991, are both based in the Netherlands. Magnum is the newest of the three and was founded in 2002 in Everett, Washington by a team of engineers from Trace and Heart.
Remote Monitoring. As with many marine electronics companies, inverter/charger manufacturers are now embracing interoperability and interconnectivity. You may have heard the term “Internet of Things (IoT) which refers to a network of physical objects which can collect and exchange data. More and more marine companies are designing their products with this in mind. Victron recently announced a new product called the Victron Energy Blue Power Colour Control GX, which allows boaters to control and monitor Victron Multi Plus inverter/chargers, BMV energy monitors and the newer MPPT solar charge controllers. There is a USB port on the unit allowing you to connect to a GPS to include location data. As well, the entire unit can be set up for remote monitoring using the Ethernet connection and the Victron Global Remote.
The very cool part of this product is that the information can also be forwarded to Victron’s free remote monitoring website or to your smart phone using the Victron Energy app and you can keep tabs on your boat from anywhere in the world. It also allows you to monitor multiple boats. Live data includes the state of your batteries, consumption, solar yield and battery temperature. You can also configure email alarms and download historical data in CSV or Excel. The product retails for $740 and comes with a five-year warranty.
Replacing your inverter/charger is a good winter project and with the boat show just around the corner, you will have the opportunity to speak directly with manufacturers and installers. Before you go, make sure you know the size of your battery bank and how many amps you consume in a day, this will help with the decision making process.
About the author: Jeff Cote is a systems design engineer and owner of Pacific Yacht Systems, a full service shop delivering marine electrical and navigation solutions for recreational boats. Visit their website and blog for info and articles on marine electrical systems, projects and more: www.pysystems.ca.