Home FAQ Electrical & Electronics Portable generator tips and information

Social Bookmarks

Facebook Twitter Digg Delicious Stumbleupon 
Portable generator tips and information PDF Print E-mail
Written by Carlos Alvarez   
Friday, 03 September 2010 07:36

Many smaller cruisers don't have onboard generators, but you still want to have electrical power for battery charging, air conditioning, hot showers, and more.  The proper choice of portable generators is key to maximizing your enjoyment and usability.  This article discusses the various options and their compromises.


Portable generators have been a controversial issue on boating forums.  Overall however, the bottom line is that they must be used carefully and responsibly, just like onboard generators.


Any generator other than the most modern catalytic converter-equipped models will produce a lot of carbon monoxide (CO).  CO is an odorless, invisible gas that can injure or kill people rather quickly.  It is absolutely vital to have at least one CO detector on any boat with a generator, and preferably two.  One in the cabin, and one in the cockpit.  The cockpit can fill with CO and be dangerous, just like the cabin.  In fact many people have died while sitting on the swim platform or in the water near a boat that's running a generator.


The second concern with a portable generator is making a safe connection to your shore power inlet.  Most small generators have a household 15 amp outlet, while most boats have 30 amp or 50 amp twist-lock connectors.  You can buy an adapter that consists of a 15a plug and 30a or 50a jack and a short piece of cable.  These typically cost $40-80, and require that you use your heavy shore power cable to make the connection to the boat.  A nicer option is to build your own cable with the right ends.  You can buy a 12 gauge (minimum size) extension cord at any hardware store, remove the female 15a end, and attach your own 30a or 50a female jack.  This ends up costing less than the adapter, and then you don't have to use the heavy shore cable for the generator.  It's more convenient and lighter to use this cable.  This cable is not waterproof though, and should not be used in the rain.  But then again, neither is your generator!


Now you have to decide which generator to buy.  Prices for small generators vary from $200 to around a thousand.  Many people ask themselves why they should consider a $1000 generator, when the cheap ones "look" the same.  There are many reasons, and I have experience with quite a few of the options.  My choice would always be the Honda or Yamaha, based on experience with the others.


There are two basic types of generators; straight-feed "contractor" types, and inverter-based "suitcase" types.  The contractor type is easily spotted by its open construction, typically inside a frame made from bent tubing.  These are loud, connect the load directly to the internal generator, and are cheap.  The "suitcase" type are enclosed in a plastic box with a carrying handle.  These are much quieter, and they have an inverter to drive the load rather than driving it directly from the internal generator.  A straight-feed generator must always run at very high RPM (3600) in order to maintain 60hz electrical power.  The inverter types can run at any speed, saving on fuel and reducing noise.  Needless to say, you want an inverter type on a boat, or you're going to be very unhappy with the noise.  And so will anyone around you.  These generators always cost more than a contractor-type generator.


Within this type, there are many sizes and quality levels.  First let's talk sizing.  The most common levels are 800-1000 watt "mini" models, 1800-2200 watt standard models, and large systems in the 3000 watt range that include electric start.  The mini sizes typically weigh less than 25 pounds, so they are very easy to handle and carry.  However, their power output is lower than most people would want on a boat.  This isn't even enough to run a 50a battery charger at full power, and certainly not enough to run any air conditioning unit on a boat.  I know very few people who use these small ones on a boat.  The next option, at approximately 2000 watts, is the most common on boats.  This will run the charger with no trouble, and will also work with most small air conditioners in the 7000-10000 BTU range.  It can run most water heaters, electric stoves, and microwaves (though not all at the same time of course).  These generators weigh around 45 pounds, and are still no burden to carry, move around, and use.  The next level, at around 3000 watts, is also not used very often on boats because of the weight.  They are in the range of 150 pounds because of the electric start system, so they can't simply be lifted and put where you want them.  They are on wheels, and they are rather large.  They won't fit through most transom doors.  They can however run multiple things at once, and run large air conditioning units.  The electric start is convenient, and most have an option to add a wireless remote start for about $100.  These units also usually have a 30a twist-lock outlet, eliminating the need for a special cable or adapter.


Once you decide on the size you want, you have to decide on a brand and price.  The Honda and Yamaha models are at the top of the price range in each size, but they also have significant advantages over the cheap off brands that seem to be the same.  I've owned a cheap knock-off of the Honda, and know quite a few people who have used other cheap inverter generators.  For the most part they are alright, but they are never the same as the Honda or Yamaha.  Some of them are noisier, though some are the same.  Noise ratings are often misleading because they will give the rating at 30' away, while the Honda and Yamaha ratings are at a closer distance.  You'll never be 30' away from the generator on your boat.  None of the cheap ones I've tried have lived up to their ratings.  My Kippor generator, for example, was rated the same as the Honda and looks almost identical, but it can't start our AC unit and shuts down with the water heater.  The Honda can run them.  I've heard reports of the same thing about various other cheap brands.


Another important consideration is warranty, service and parts.  When my Kippor got a saltwater bath in a storm, the inverter board blew.  I live in one of the top five metro areas, yet the closest service and parts center was 100 miles away.  On top of that, they were out of stock on the part and it was going to take "at least" two months to get it.  This is when I switched to a Honda.  They have multiple local service centers and all of them stock all parts.  The one I bought it from guarantees reapirs in 48 hours.  Additionally, there are Honda service centers near most ports, so you can get it repaired if you're on a cruise and have a problem.  Yamaha is better than the off brands, but not quite as good as Honda.  They have fewer service centers.  However their generators typically have a few more features than the Honda, such as a 2200 watt model with a twist-lock connector.  The warranty on many of the cheap brands is only 90 days, while the Honda and Yamaha have a year warranty.


A final consideration is the quality of power you get from the generator.  See this file for some tests of various generators' power output.  They are not all the same, and some may damage or fail to run certain electronic devices, even microwave ovens.  My microwave was noisy when running on the Kippor, but sounds normal with the Honda.  This is because the quality of power is much better with the Honda (a true clean sine wave).


Consider all of these compromises, and then make the best decision for your needs.  Just don't be fooled into thinking that the $500 off-brand generators is "just like" the Honda or Yamaha at nearly $1000.


Last Updated on Friday, 03 September 2010 08:05
Copyright © 2013 CruiserTips. All Rights Reserved.
Joomla! is Free Software released under the GNU/GPL License.