13 Apr


Power Play!

Are You Maximizing Your Power Sources?

By Don Wilson
TECH DOCTOR DON WILSON has worked in technical capacities in the marine, automotive and RV fields and for the military since 1989 and has extensive experience in designing and troubleshooting onboard electrical systems. A former customer service manager dealing with electronic issues, Wilson currently serves as a technical instructor for the RV industry’s RVIA Trouble Shooters Clinics and is a full-time sales application engineer for Xantrex Technology, Inc. POWER PLAY! is the first installment of TECH DOCTOR articles being presented by the Boat and Yacht Report.

 When you’re out on the water, do you take full advantage of all of the power sources on your boat in the most effective manner possible? Unless you have a complex, automatically controlled system, you probably don’t. Consider of all the power sources you may have: shore power, generator, inverter, alternator, solarpanels, wind turbines, nuclear (okay, maybe not yet). What are the primary benefits and limitations of each, and how can you maximize your efficiencies?

 Shore Power

Obviously, the key benefit of shore power is that it is constant, so long as you’re docked and the power grid is not interrupted.

Eaton Admiral Shore Pedestal

This doesn’t necessarily translate into “unlimited” power however (since it varies according to the shore breaker size), but at least it’s not intermittent. The good news is that you can power all of your onboard devices and charge renewable storage (batteries) as fast as possible, or slower if other demands on the boat increase, while holding them at full charge in preparation to unplug. The main limitation to shore power is that it’s not portable, which is kind of the point of owning a boat, isn’t it?




Onan QD 60Hz 27.5kw


The main benefit to the generator is that it’s an onboard source of AC current. It’s like taking your shore power with you, except it uses fossil fuels which are limited in supply until you can return to shore. The best way to use a generator is to use it at full bore and shut it down when demand drops below 50% of the generator’s capacity (more on this in the inverter section).


When you are underway, your alternator is spinning relentlessly, providing amperage for charging the engine batteries and running electronics. However, once the engine battery is fully charged,what do you do with the alternator? Here’s a nifty tip! If you have a 200A alternator, and the electronics draw less than 50A, consider engaging your battery combiner to channel some of the available amperage to your house batteries. It will charge just like your generator would, but without another engine running!


Solar and Wind

Solar and wind are related since the sun doesn’t always shine and the wind doesn’t always blow. These would be supplemental chargers for the battery bank just like the alternator as described in the previous paragraph. Once the house battery is charged, can that excess current be used for another bank? Combine them to take advantage of the free resource…okay, it might not have been free when you priced the components, but since you already have it…use it!


Xantrex Freedom HF Inverter

The inverter is a smart substitute for the generator and can even partner with it to produce an efficient use of resources. An inverter really shines when used in two conditions. First, it delivers a low power draw for a long period of time, ideal for use with entertainment systems, or small electrical devices. Second, it is perfect in providing a large draw for a short period of time, say for usage with a microwave, or perhaps a short-term motor. Both of these scenarios are terrific applications for an inverter, whereas using a generator would be totally inefficient. Running a 15kw generator for 500W of electronics doesn’t make sense, and running a generator at 50% capacity for two to five minutes doesn’t allow the engine to warm up, and will eventually wear out engine components. These types of conditions are best suited to the inverter, until the batteries are in need of a charge. At this point run the gen for air conditioners, and charge those batteries back up, then go back to invert.

The Bottom Line

The key to maximizing your power efficiency is to use the available power sources you have to the full benefit of your system. Don’t let a power source go idle when that resource can be directed to another component of your system to be used later.


Next up from Don Wilson: Why is Regulatory Compliance Such a Big Deal? What’s the risk if your onboard electronics lacks it?


1 Comment

Posted by on April 13, 2011 in Uncategorized


One response to “TECHNOLOGY

  1. power converter

    April 15, 2011 at 6:54 am

    Now this is hghly recommeded post for me. I will surely email this to my friend, Regards, Young Ai


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