A necessary spare tire.
Off grid amateurs have a love-hate relationship with gas engine generators. Due to generators requiring constant refueling and ongoing maintenance, they are not a realistic long-term power solution. Most of them are noisy, many are poorly made, and all of them are dirty. Yet, they are effective, affordable, and can produce a lot of power for their size.
Generators are broken down into three basic types: conventional gas, inverter, and diesel. What is the difference between these? Which is “best”? Do you even need a generator if you already have solar or other off grid energy available? Let’s sort it out.
Our purpose is not to steer you in any one direction. Instead, we’ll go over the different types of generators and offer insight to help make an informed decision.
It’s a mad, mad, mad, mad world!
If you’ve ever done any internet research on generators, you already know there is a lot of information overload floating about. For every person who says generator XYZ is great, there is someone else insisting it’s a pile of junk. All claims, at least on the surface, seem plausible. YouTube alone has perhaps tens of thousands of videos representing every possible generator opinion.
When doing your research, be aware of the intentions of the people from whom you seek information. Many YouTubers and bloggers receive free products in exchange for promotion, or are “affiliates”. Being an affiliate means that the content creator gets paid a cash commission when anyone buys products through a sales code or link associated with their website or channel. In other words, they have a “sugar daddy”. Content creators have a strong motive not to trash-talk about their benefactor’s products!
Even paid shills can be helpful.
This is not to say the advice of compensated reviewers is by default untrustworthy. You certainly can glean a lot of valid information from these folks. They are not necessarily lying, but they are very selective with their truth.
The point is to be very cognizant and read between the lines. Why are they saying what they are saying? What are they not saying? By the way, Off Grid Ham does not have any sponsors or affiliates, and it’s not because I’ve never had offers. Everything on this website is original, transparent observations free of ulterior motives.
Conventional generators: The ageless standard.
Producing 500-10,000 watts from a small single cylinder engine, conventional generators are easily available at any power tool retailer. They are by far the most popular generator format. These generators operate by rotating a metallic wire loop, called an armature, in a magnetic coil, called a stator. As the loop rotates, current is created.
Each rotation through the north-south poles of the magnetic field produces one complete alternating current cycle. To get 60 cycles per second of AC current, the device would have to turn 60 times per second. That multiplies out 3600 revolutions per minute. Conventional generators must maintain a constant 3600 RPM no matter what the load is, or the frequency will drift off the expected 60 Hz.
Conventional generators have some significant disadvantages. First, inefficiency. Whipping around at 3600 RPM drinks a lot of fuel. Second, the market is rife with poorly made units. The vibration and high speed is physically stressful and makes the generator prone to mechanical failure. Then there is the noise. These generators are famously loud, so much so that they are appropriately nicknamed “screamers”. YouTube is loaded with advice on how to quiet them down.
Some generators will turn at 1800 RPM. This is achieved by adding a second coil/loop on the armature. The engine is turning at half the speed as a 3600 RPM model, but creates the same number of electrical cycles with each revolution. The end result is a 60 Hz power output. Most 1800 RPM generators are diesel-fueled. Small 1800 RPM gas generators are exceptionally rare.
Conventional generator lifecycle.
How long one can expect a generator to last is highly speculative and depends on the devices’s initial build quality and how it is used. For example, a low-end generator beat to hell daily on a construction site may only last a year or two. If the same generator is treated well and used occasionally for short term power outages, it might last many years. Generator lifecycles are measured in hours of runtime. The less a generator is run the longer its total service life will be.
Higher quality generators can provide decades of reliable service if cared for properly. I have a 30 year old Honda conventional generator that was already 20 years old when I got it. It has probably thousands of hours on it. That old man still starts easily and runs great every time. If I had to replace that generator today it would cost 4-5 times as much as a comparable off brand model.
It’s the age-old question: Should you spend more up front and invest for the long term, or spend less now and spread the expense out over more than one purchase? Each individual will have to make a decision based on their needs and budget. Of course, buy the best if you can. For radio amateurs on a small budget who don’t expect to roll a lot of hours on their generator, it may be financially sensible to buy a low tier machine with the expectation that it is not a lifetime investment.
What if anything can be done to avoid living with an obnoxious “screamer” that slurps a lot of fuel and must always turn at 3600 RPM? For the off grid ham, the go-to solution is an inverter generator. Inverter generators turn an alternator just like their conventional brothers. Instead of connecting a load directly to the alternator output, inverter generators add a few extra steps.
The output of the coil/alternator feeds a rectifier, which converts the AC to DC. The DC is then run through an inverter, which creates a 60 Hz AC output from the DC input.
If this sounds like a lot of extra complexity to arrive at the same place, well, it is. It’s not for nothing, though. If we dig a little deeper into how inverter generators work, the extra steps make sense.
Inverter generators eliminate the need for the engine to run at 3600 RPM all the time. Instead, it can turn faster or slower according to the load. This makes for quieter, more fuel efficient operation. As the engine changes speed, the frequency of the alternator output will change too, but it does not matter because the rectifier converts it to DC anyway. The inverter will make a nice, clean 60 Hz AC output no matter what the speed of the engine may be.
The extra hardware and circuitry drive up the cost of inverter generators, compared to a similar conventional model. Is it worth it? Again, that’s a personal decision. From an off grid radio operator perspective, other than lower initial cost, conventional generators have almost no advantage over inverters.
Inverter generator lifecycle.
Like the others, inverter generators are available with widely varying build qualities and price points. The Honda EUxxxxi-series is at the top of the pyramid of inverter generators and has a price tag appropriate to its stellar reputation. Lower-tier off brand inverter generators often look a lot like Hondas and can use Honda parts because many of them are knockoff clones.
In terms of build quality and expected service life, do not assume inverter generators are inherently “better” than conventional generators. While it’s true that inverters do not have the same mechanical stresses as conventional models that run at 3600 RPM, all the same caveats and warnings apply.
Basically, there is Honda and there is everything else. If you go with Honda, you have little to worry about. When used & maintained as designed, a Honda will last for decades. If you go with anything else, do your due diligence. There are some great inverter generators out there that are not Hondas. Yamaha makes an outstanding line of inverter generators. The only caution with Yamaha is that in the USA, their service and parts network is not very robust…but then again you’ll not likely need it!
Gas is the most popular fuel, but there is also propane and natural gas. Many generators come from the factory with bi-fuel or tri-fuel capability. If your gas generator does not have this option, aftermarket conversion kits are easy to find, relatively inexpensive, and can be installed as a DIY project. Even if you don’t think you’ll immediately need it, tri-fuel gives you more options if fuel becomes scarce.
If you have access to a farm tractor with a power take off, consider getting a stand alone generator that will connect to your PTO. These generators are not as portable as you might like, but you have the advantage of not having to buy and maintain a separate engine.
Lastly, we have diesel. Diesel generators are in a class by themselves. Diesel generators small enough for personal off grid use do exist, but they are rare. The other issue is the cost. A diesel generator will cost many times more than a comparable gas unit and they cannot be adapted for tri-fuel.
Yanmar Diesel makes a highly respected small portable diesel-powered generator (brace yourself for sticker shock!).
This Off Grid Ham article from 2016 discusses inverter generators in greater detail.
What is your generator experience? Tell us your story in the comment section below.