Electric Generators


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Choosing a Good Generator for Backup Power

If you've come to this page, then you are probably looking for more information about making a good choice of a generator as a backup power source.  There are times when activities (work or recreational) must be done far away from a source of power.  In these cases, a generator can provide a good source of portable electricity.  In addition, during extended power outages, a backup generator can provide emergency power to keep the refrigerator running, lights on, and the ability to live more comfortably when utility power is not available.  In today's world, most of us take reliable electric power for granted.  You wake up in the morning in a comfortable climate controlled home, flip on the lights, turn on the TV, heat something in the microwave, start your computer, and so on.  Almost everything we do in modern society is dependent on electricity.  When it's not there any more, people quickly take notice!  Just ask someone that has lived through an extended power outage due to a natural disaster such as an earthquake, tornado, hurricane, flood, or snowstorm.   Life can be dramatically changed in the blink of an eye.  We may not be able to predict every disaster that can come our way, but we do have the ability to think ahead and make some preparations.  That's where an electric generator can come into play.  A generator is one simple and practical way in which you can prepare.

Backup Generator   

Let me start off my saying that I've spent a lot of time researching generators.  My background is in mechanical engineering and I've tinkered on engines and mechanical devices most of my life.  What I'm sharing with you here is based on years of thinking about this topic, and it is also based on quite a bit of real life experience with both engines and generators.  I specifically mention engines because a good generator must also have a good engine.  There are 2 basic parts to a typical generator: a electrical generating head, and a power source to spin the generator head.  Typically, this power source comes in the form of an engine.  It makes no difference if the generator you choose comes with the greatest electrical generating head known to mankind, if the engine that spins it is unreliable, then you'll just end up with an expensive boat anchor.  Below I will try to list out some important factors to considering when looking for a good generator.

1)  PICK THE SMALLEST GENERATOR THAT WILL MEET YOUR NEEDS - In our world, often times the "bigger is better" idea is promoted, but that's not necessarily true when it comes to a generator.  You see, you have to feed that generator with some sort of fuel, whether it be: diesel, gasoline, propane, or natural gas.  You will find that generally speaking, the bigger the generator, the greater the fuel consumption.  There are other factors such as fuel efficiency differences between engines run by different fuels such as diesel or gasoline.  There are also electrical factors such as whether the electrical system is conventional or inverter type  We'll touch on those a little more later, but at this point let's just state the following general rule.  A larger generator will consume more fuel than an otherwise similar generator of smaller size.  Let me clarify here that when I saw "size", I'm referring to the power generating capacity of the generator.  It is true that a generator capable of producing more power (kW) will usually also be larger in physical size.

Back to the question at hand, how big of a generator do you need?  This is something that you will need to determine for yourself.  You will need to go through your home and decide which items you want to operate during a power outage.  Write these items down on a piece of paper and make yourself a list.  Then go through the list and find out how much power is required to run each item.  A good way to determine these power consumption numbers is with a device such as a Kill-A-Watt meter which measures power drawn.  You plug the Kill-A-Watt meter into the outlet and then you plug the device into the Kill-A-Watt meter.  When the device is operating, the meter will display the amount of power being consumed in WATTS.

Power Consumption Meter 

In addition to measuring the power usage directly, some appliances will have a tag that displays the power consumption of the item.  For example, you might see on the label on the bottom of your coffee maker that it uses 600 watts.  Write this down.  When you get to devices that have electrical motors, things can get a little more complicated.  An electrical motor requires a surge of power to get started.  Once the motor is running, then the power consumption drops considerably; however, you need to make sure that the generator you choose will be able to supply the needed power to start off these motors even if the power surge required is only for a split second.   In addition, be aware that large 240V items such as ovens, furnaces, dryers, and water heaters will be BIG power hogs.  In many cases, it will not be practical to power these items from a generator, unless you buy an extremely large generator that will waste a lot of fuel.  For emergency backup, it's often best to plan to not power these large 240V appliances.  Even without a stove to cook on, you can still cook in a microwave or on a small hot plate that will use less power than a full size range.  With all that in mind, let's say that after you go through your home, your list looks something like this.

Refrigerator 325 watts 975 watts
Television 200 watts 200 watts
Coffee Maker 600 watts 600 watts
Computer 175 watts 175 watts
Portable Heater 1,300 watts 1,300 watts
Well Pump (1HP) 1,250 watts 3,750 watts
  3,850 watts 7,000 watts

Now, this is not a very comprehensive list, but it's just made up for the sake of discussion.  One of the things you will notice in the list is that devices such as the refrigerator and well pump require a large surge of power because they have electric motors.  As a general rule, an electric motor will require a 3X surge of power just to get it running.  Once it's running, then its power consumption will drop significantly (typically to about 1/3 of power required to start).  A few other comments related to the list shown above.  You can see that if you have a well pump that supplies your household's water, then you will need a much larger generator than a person that has city water.  Depending on the size of your well pump motor, you could easily need a generator twice as large as someone else living on city water.  Water is essential, so if you have a well pump, make sure that you choose a generator capable of running your well pump!  A quick note about well pumps... most deep well pumps run on 240V so you will need to make sure that your generator comes with a 240V output.  Some generators (usually the smaller ones) only come wired for 120V output.  Another thing to notice for this list is the fact that you would need a relatively large generator if you tried to run all your devices at the same time.  Thankfully, this is not usually the case.  After all, you probably won't be running your coffee maker all the time (unless everyone in the neighborhood is over at your house because you were the only one smart enough to prepare by getting a generator)!  In addition, a refrigerator cycles on and off as needed to keep things cool.  Same is true of the well pump.  It only runs when needed to supply water.  So, you have to consider the fact that not everything will be running all the time.  In addition, it really is best to learn to manage your loads during a power outage.  That means that you need to think about what you have running and be careful not to try to power up anything that might overload your generator.  For example, let's say that you want to use your microwave to heat up some food.  You might need to shut off your portable heater before you use the microwave.  If you manage your electrical loads wisely, you can survive with a much smaller generator.  Sure, it's possible to get a BIG generator that will supply all your electrical needs like when living normally on utility power, BUT you better have a big fuel supply (and a big wallet) to be able to feed that generator during an extended power outage.  Even if you have a big pocketbook and can afford to pay for a lot of fuel, it won't do you any good if fuel supplies are shut off or limited because of a disaster.  Just look at what has happened during natural disasters in the past.  Power outages can be quite extensive and most gas stations will not be in operation unless they were wise enough to have a generator backup.  A gas station without electricity will not be able to pump gas out of their underground tanks.  So, you might have lots of money, and there might be lots of fuel at the gas station, but none of that will do you any good if the fuel in not accessible!  That brings up another important point to remember. 

2)  KEEP A SUPPLY OF FUEL ON HAND - As already stated, a generator will not be useful unless you have the fuel required to run it.  Whatever generator you end up choosing, be sure that you are able to safely store some of the necessary fuel.  For many people, a gasoline generator will make a lot of sense, because most people have gasoline powered vehicles and equipment around.  In that way, if you store some gasoline for use with your generator, you can rotate your fuel supply periodically by using the stored gas in your vehicle and then refilling the gas cans with fresh fuel.  If you have a diesel vehicle, then you can do the same thing; however, storing diesel for a longer period of time is not as much of a problem as gasoline.  Trying to store modern gasoline for a longer period of time can be very difficult.  Most modern gasoline has ethanol and it is made in such a way that it just does not store well.  That's why it's important that if you store gasoline for your generator that you are able to rotate your fuel and use it in a car for example, so that you can store fresh fuel for your generator.  Personally, I would not want to store gasoline for more than about 4 months, unless I added some high quality fuel stabilizer like Power Research PRI-G.  A healthy dose of Stabil would be my 2nd choice but I prefer the PRI-G.  With a good fuel treatment, it is supposed to increase the storage life of gasoline for up to 1 year.  I'd say that even with fuel stabilizer added, it would be best to use the fuel in a car and rotate your fuel storage with fresh gas at least every 9 months or so.  Now, in regards to diesel fuel, it is much more stable for long term storage.  Assuming that the fuel is clean and uncontaminated (no water or other material that promotes algae growth), then I'd be comfortable storing it for up to 1 year untreated.  However, personally I think that it is cheap insurance to use a diesel additive like PRI-D just to be safe, even if I thought that I would use the fuel up within 1 year.  With PRI-D treated diesel fuel, I would feel safe to store it for up to 2 years.  When storing diesel for long term use, one thing to keep in mind is if you buy diesel fuel in the summer months, then you might have problems with fuel gelling and wax crystals forming in the diesel during the winter.  The reason for this is because fuel is blended at the refineries according to the time of year when it is expected to be used.  So, during the winter months, diesel is formulated to work with lower outside temperatures.  If you buy diesel fuel for your generator in the middle of winter (and you live in an area that gets cold in the winter), then the diesel fuel you buy should be safe for storage all year around.  On the other hand, if you buy diesel fuel in the summer, you should consider buying a diesel additive such as Power Service Diesel Fuel Supplement.  This should help to prevent diesel fuel gelling during the winter if the temperatures drastically drop.  When diesel fuel gels, it can quickly plug up filters and shut down an engine.  It's best to be safe and make sure your fuel is protected against low temperature gelling.  Regarding fuel additives for gasoline or diesel, it is best to pour the appropriate amount of additive into each storage container before filling with fuel.  In that way, the additives will be completely mixed throughout the fuel and you can be assured they will be most effective.  It is not a good idea to just pour some additive into a full storage container, unless you can thoroughly mix it afterwards.  This might be possible with a 5 gallon jug, but it would not be practical with large fuel tanks that will be very heavy when full.  One final word on fuel storage related to propane or natural gas, and that is you won't need to worry about fuel degradation with these gaseous fuels.  That's one of the benefits of gaseous fuels such as propane.  You can store it for a very long time and not have to worry about it going bad.  In summary, listed in the order of which fuels keep best in storage, you have: propane as first choice, then diesel, and finally gasoline.  With that being said, I would probably recommend gasoline for many people, because it is a common fuel that most people already use on a daily basis in their vehicles, to mow their yards, and in other outdoor power equipment.       

3)  SPECIFIC RECOMMENDATIONS - In terms of a specific generator that I would advise many people to consider, it would definitely be a gasoline powered inverter type such as the Honda EU2000i or the Yamaha EF2000iS.  This recommendation would be for people living on city water.  If you have a well, then you will need something bigger.  For most people, I specifically pick these models because they offer an excellent combination of: good power output (kW), excellent fuel efficiency, portability (low weight), high quality power output (pure sine wave), and great reliability.  The Honda has been around longer and has an excellent track record with some units faithfully serving for many 1000's of hours.  The Yamaha has not been around as long, but it also has a record of excellent customer satisfaction.  Personally, I prefer the Yamaha EF2000iS just because it has some features that I like better such as a steel camshaft versus the plastic camshaft in the Honda.  In addition, the Yamaha has a fuel gauge and a fuel petcock for shutting off the fuel supply.  This can be helpful when storing the generator.  You can turn the fuel off and let the engine run until it uses all the gas in the carburetor and then the engine will shut down.  It's best not to store an engine with gasoline in the carburetor, because if the fuel does go bad, then the carburetor can get gummed up with deposits that will prevent the engine from running right (if at all). 

Honda EU2000i     Yamaha EF2000iS

Popular Honda EU2000i and Yamaha EF2000iS Generators

With my personal preference of the Yamaha aside, let me say that I don't think you can go wrong with either the Honda or the Yamaha.  Both are excellent generators and both offer very similar specifications.  Both are lightweight with the Honda weighing around 46 lbs and the Yamaha weighing 44 lbs.  Both generators are fuel efficient with both of them sipping gasoline at the rate of only 0.1 gallons per hour at 1/4 load.  They are both quiet generators with the Honda noise output ranging from 53 - 59 dB, and the Yamaha noise output ranging from 51.5 - 61 dB.  As you compare the specs further, you will see that both are rated for 1600 watts continuous with a 2000 watt surge rating.  In addition, both of these generators are inverter generators which produce very clean pure sine wave power output that is good for powering everything (including sensitive electronic equipment).  So you can see that both generators are extremely similar.  If this size of generator fits your needs, then either one would be a good choice. 

GASOLINE GENSETS - If you will be getting a gasoline powered generator, then an inverter type like those shown above (or a larger one) is highly recommend not only for their clean power output, but also because of their extremely good fuel efficiency.  These inverter generators are designed to automatically vary the engine speeds according to power demands.  What this means is that if the generator is under a light load, then the engine will slow down to match to lighter demand put on the it.  This can save a tremendous amount of fuel when running a generator a long period of time.  When additional power is needed, the generator quickly increases engine RPM as much as is needed to match the increased load.  These inverter generators are marvels of engineering.  If you are going to get a gas generator, then seriously consider an inverter type.  If you've done your calculations and you know that you need a bigger generator, you can find Honda inverter generators with capacities of up to 6,500 watts, and Yamaha inverter generators up to 6,300 watts.  You will pay more for an inverter generator, but if you ever need to run your generator for an extended period of time, then one of these inverter generators can quickly pay for itself in terms of fuel savings in today's world of high fuel prices.  Think of it sort of like buying a car.  Perhaps you can buy a car that gets 27 mpg for a lower price than a more fuel efficient car that gets 38 mpg.  It might be tempting to buy the less expensive car thinking that you will be saving money; however, in reality you might end up spending more in the long run because of the higher fuel expenses.  That's sort of the way it is with generators.  An inverter generator will cost more, but you need to also factor in the cost of fuel.  Also related to pricing, beware that the market is full of cheaper inverter type generators.  I hate to sound as if I think more expensive is always better, but in terms of generators I'd advise you to stay away from the cheaper inverter units because most of them are made in China and many of them have a proven track record of problems.  There are many different brands, but if you are going to depend on this generator in an emergency, then I suggest just sticking with the tried and true red and blue (Honda and Yamaha).

Honda 6500 Inverter Generator 

Large Capacity Honda 6500W Inverter Generator

DIESEL  GENSETS - If you are in a position where you use diesel fuel regularly in a vehicle or in other ways such as in farm equipment, then you might want to consider a diesel powered generator.  Diesel engines are more efficient than gasoline engines, and a diesel genset will typically use much less fuel than a similar gasoline generator.  That is because a diesel engine has a very high compression ratio and it is able to extract more energy from the diesel fuel that it burns.  It is my opinion that some of the best diesel generators ever made for home backup power are the older Onan diesel generators.  The Onan DJA, DJB, DJC, and DJE series of generators are known for their legendary longevity and their impressive fuel efficiency.  They are air cooled, so they are simpler and do not have liquid cooling system to fail.  They are can be hard to find in good condition, since they haven't been made since the 1990's. The DJ series of diesel generators were first produced in the 1960's, so production spanned 3 decades.  As a result, you can still find these generators, but often times they are in rough shape and some have a lot of hours.  Speaking of hours, it is not unheard of to find one of these generators running for OVER 10,000 HOURS before needing a major rebuild as long as regular maintenance was not neglected.  These generators are truly impressive machines.  The earlier units came with the Onan Magneciter generating head.  During later production, they were switched over to an Automatic Voltage Regulator (AVR) controlled generator section like the late production 6.0 DJE shown in the picture below. 

Onan Diesel 6kW Generator

Onan 6.0 DJE 6kW Diesel Generator

This particular Onan DJE generator shown in the picture above has very low hours and was picked up on auction from a government agency.  It turns out that the AVR circuit board was fried.  The list price by Cummins (which took over Onan) for a replacement AVR board was OVER $1,800!  That brings up an important point with these older generators.  I would not recommend them for just anyone, but instead are best suited for a mechanically inclined person that has some experience working on things themselves.  In the case of this particular generator, an aftermarket AVR was purchased from a company known as Flight Systems.  For a little over $200, the aftermarket circuit board got this low hours genset working again and gave it a new lease on life.  This particular unit has started large electric motors with start up surges OVER 20,000 WATTS.  That's with a 6kW rated generator!  Suffice it to say that Onan rated these DJ series diesel generators conservatively.  Over a 12 hour period, this generator was able to run a household on a limited basis and only used around 3.5 gallons of diesel.  That's around 0.3 gallons per hour running at light loads most of the time.  In most cases, with greater loads, an Onan 6kW DJE generator like this will probably be closer to 0.5 gallons per hour fuel consumption.  Under heavy load, it will probably be more like 0.75 gallons per hour.  One of the nice things about a diesel generator is that fuel consumption usually goes way down as engine load goes down.  Gasoline generators do not usually conserve fuel as well at lighter loads.  This is just one of the benefits of a diesel generator, especially those running at lower engine speeds.  By the way, these older Onan gensets are designed to run at 1,800 RPM.  That's 1/2 the typical 3,600 RPM that you will find in many other generators.  The lower engine speed is what helps contribute to greater fuel efficiency and better engine longevity.  These old Onan generators are impressive machines, but once again I would only recommend them for someone who is able to work on their own equipment since chances are that there will be some repairs necessary on these older gensets.  For those not able (or not interested) to work on an older generator, there are a lot of different diesel generators available on the market that you can buy brand new.  I'll discuss a little bit about what's available on the market today.

Robin Diesel Generator

Robin RGD5000H Diesel Generator

Let me share with you something that I do not  recommend.  I do NOT recommend that a person go out and buy one of the many cheap Chinese made diesel generators that have flooded the market.  In most cases, you will probably deeply regret your decision.  Sure, you might get lucky and get a Chinese brand and a particular genset that is OK, but the great majority of these generators will only cause their owners grief in the long run.  You might think that you are saving money by purchasing one of these, but the reality is you might be throwing your money away on a cheap generator that will need to be replaced in a short time.  Spend your money wisely one time, rather than having to buy twice because you made a bad first choice.  I understand that after you see the prices of a quality made diesel generator, then it can be very tempting to buy one of these Chinese units for 1/2 the prices (or less).  Just resist the temptation and keep your eyes focused on the purpose of this generator.  The purpose of a backup generator is to provide emergency power during power outages.  Sometimes, you won't know how long the power might be out.  During an emergency, the last thing you want to find out is that your cheap Chinese generator does not work properly or prematurely fails.  Invest in something that you can depend on to provide emergency power for you and your family.  I would recommend buying a name brand generator.  That recommendation does not just apply to diesel generators, but also for gasoline and propane powered generators as well.  Specifically, in terms of diesel powered units, I would recommend generators from companies like: Robin-Subaru, Pramac, Dayton, Winco, or Yanmar.  Almost all of these newer, smaller portable generators run at 3,600 RPM.  This means that they will usually not be as fuel efficient as a slower running diesel engine, but they are still typically much more fuel efficient than a comparable 3,600 RPM gasoline powered generator.  In addition, these small diesel engines are usually made better and have a longer lifespan than a typical gasoline generator engine.  There are some other brands of generators that use name brand diesel engines.  Whatever you end up getting, just be sure that the engine comes from an established well known diesel generator manufacturer like: Hatz, Lombardini, or Yanmar.  Speaking of Yanmar, be aware that the market is flooded with Yanmar clone engines made in China.  Once again, you might get a decent one or you might get a lemon.  No matter what Chinese clone that you get, you will likely not get anywhere near the reliability and longevity of a quality made diesel engine.  If you get into larger gensets, then you will likely get into bigger liquid cooled diesel generators.  In that case, make sure the engine is made from a reputable company such as Kubota or Perkins.  Stay away from Chinese engines unless you know for certain that you are getting a brand that has a track record for being reliable.  If in doubt, pass on it and look for something that you can count on during an emergency.

In conclusion, calculate your electric needs for running the most important items in your home.  Then buy the smallest, most fuel efficient generator that you know will meet your needs.  Pick a high quality genset that will be reliable and have the potential to serve you well for many years.  Be sure to have fuel stored and available to run your generator in the event of a major power outage where gas stations may not be able to sell fuel.  Don't forget to use fuel stabilizer to help keep your fuel fresh and ready for when you need to use it.  Periodically test run your generator to make sure everything is working properly.  In the midst of an emergency is not the time to discover that your generator will not start or work properly.  Finally, hopefully things will go well and you won't need to use your generator too much.  If you do need it, then at least you'll have the peace of mind knowing that you have done your part to try to prepare for the unexpected.