There are many reasons why you might be considering buying a generator. In this article, we will look at portable generators and whether a used one is a good choice.
Buying a used portable generator can be considered if it has been well maintained. Check all common problems before purchasing, especially a load test.
Buying anything used is always a risk. But doing your homework and buying for your needs will arm you with the knowledge when going to view one.
Mobile Generators Types
There are a ton of generator makes and models out and knowing what you want or even what you don’t want will help make the buying process a lot easier. Generators come in many different dimensions, electrical output ranges, engine sizes, even fuel types. Most run on straight gas, some are 2 stroke and require mixed gas, some are diesel (usually larger generators), some are LPG, and some are dual fuel (gas and LPG).
Generators all produce electricity, but crucially the electricity they produce isn’t all the same, generators come in two basic flavors – An inverter generator and an AC generator.
We’ll need to decide which one is right for you before we can go shopping and so let’s take a look at what makes them different before getting into my top tips for buying a used one.
1 Inverter Generator
Using a generator anywhere that you think you might power a laptop or computer is important to note that you must have an Inverter Generator. Generators are AC powered. Without an inverter, there is a chance of a power surge which will basically damage your laptop or PC. Be wise, if you’re not sure, don’t plug it in.
An inverter changes AC current into DC and then back to AC. This means the power doesn’t alter or surge and the quality of the electricity is safe to power a laptop or a smartphone.
They are especially favored by campers because they are laptop and phone safe, lightweight, quiet, easy to store and use.
2 Alternating Current (A/C) Generator
A standard AC generator works by using an alternator to convert gas power into electricity. If you are powering general household items, such as lights, or a water pump then an AC generator will work perfectly.
AC generators are ideal for power outages and for working on-site but don’t be tempted to plug your laptop, into an AC generator.
AC generators tend to be bigger, heavier, noisy, and are best suited for work sites.
How can you tell an inverter generator from an A/C generator?
An inverter generator is usually smaller in size and certainly much quieter. It is very fuel-efficient and ideal for running laptops and smartphones as it’s designed to protect sensitive equipment from damaging electrical power surges. It is a much cleaner way of generating power and these types of generators also allow you to stack power.
Inverter generators are much smaller in size and quieter than a standard generator and a label on the side of the machine will clearly state “Inverter Generator”.
Inverter generators also tend to be far more ergonomic with little to no mechanical parts on show and they are, unfortunately way more expensive than a standard AC generator.
An AC portable generator on the other hand will allow you to power and run many items in your home during a power outage. It is also a much better choice for on-site use. It is a much noisier machine however and requires a constant speed of 3000 rpm to produce a normal current. If this fluctuates then the power will flutter in and out.
What are Your Needs and How Often Will You Use the Generator?
The most important question is – What do you want a generator to power?
Generally, there are three main reasons for a generator:
- Power Outage
- As Part of a Construction Site
1 Power Outage
Power seams to go out more and more these days. If this is your reason you are sourcing a portable generator then there are a few things to consider before rushing out to buy.
Firstly we need to realize that a portable generator is not going to have the power to take over your mains, you already know that.
If that’s the type of generator you are after, you’ll need to have it professionally connected to your homes electrical system. Connecting it through your homes circuit breaker panel allows the entire circuit to run – such as your lights, washing machines, air conditioning, heating etc. This type system is expensive and not the type of generators covered here in this article.
For many a handy portable generator is enough to see them through power outages, as for most they are usually short-lived.
Having a portable generator at home in case of an outage means you will also need to store gas. Storing gas comes with its own headaches. In an airtight container, stored in a heated garage, gas should be good for six months, but today’s gas is blended and begins to go stale after one month ifnot stored correctly.
Same goes for the gas inside your generator gas tank. It’s best to use a stabilizer in your generator, in fact in all your small engine kit. It keeps the gas fresh for up to two years and prevents gumming, a common cause of carburetor failure.
|Type of Load||Wattage Required||Generator Size required|
|4 Lighting Circuits||400||17kW|
Running multiples of the above will require more power. Your generator may not be able to run both a washing machine and the electric oven for example.
2 Campsite Use
The great advantage to a portable generator is in the name. Portable. Camping is a highly popular pastime and to have a portable generator on the job makes camping nearly glamping! Having a portable generator allows a little more comfort under the stars, such as the ability to cook, boil a kettle, and listen to music.
You don’t however want to hear the drone of a generator the entire time you’re camping (and neither do your neighbors!) Generators are available with quieter engines and are available in small and compact sizes. However, they are hard to come by, used, and new, they can be pricey.
The other thing to consider is gas for your camping generator. No one tends to go camping every weekend but in the summer probably much more frequently. So do you travel with your gas onboard or wait till you get to the campsite?
|Type of Load||Wattage Required||Generator Size required|
|Laptop||200||17kW (Invertor Required)|
Going camping with a generator is a smart move. However, if you plan to plug a laptop in you must ensure that it is an inverter generator.
3 As A Work Tool
The last usage option we’ll look at is as a power source on site. These portable generators could be running anything from power tools to a cement mixer. If you are looking to buy a used generator for this reason I recommend you don’t purchase one from another contractor. If they are selling one, it has well and truly had its day.
|Type of Load||Wattage Required||Generator Size required|
|Table Saw||up to 4000||48kW|
Although a smaller generator will run some power tools, the larger portable generator is the one to choose. Initial startup surges may need more power than a 17kW will be able to provide. And if you need to run more than one power tool then you definitely will require a larger machine.
New vs Used
Buying new is always going to have its advantages. Full warranty. It’s unlikely to give any trouble and if it does you can just bring it back to the store. Full range to choose from. But on the downside, new generators can be expensive. Especially if you require a high wattage model. The cost of a camping generator for example could set you back as much as $300 – $400 (and not necessarily a brand you might recognize).
Whereas one to power an outage can be upwards of $1000, and one for a contractor could be double.
So thinking about sourcing a used one is a very good idea. But trying to buy a used generator the day before you go camping or when you see a storm brewing on a weather channel is never a good idea. Buying anything used, especially mechanical or electrical (and a generator is both) takes some time and patience to find a good one.
Where to Buy
Where to buy a used item is always the burning question. There are a few options but each comes with some considerations.
Online Buy and Sell / Trading Site
Buying a portable generator from a private seller is acceptable but you need to know what you’re looking for and have a list of questions at the ready.
- Have they owned it since new?
- How often has it been serviced?
- Where did it spend most of its days?
- Is there a user manual or guide to go with it?
- And the most important question – why are they selling it?
If the answer is to upgrade to a higher spec then that’s a valid reason.
If the price seems too good to be true, well, the reality is, it probably is. People don’t generally sell generators. If they’ve gone to the bother of buying one, there was a reason for that, and those reasons don’t usually go away.
Private sellers of generators are usually at Flash Sales, when someone is moving (also a valid reason for selling) or if someone has passed away. Also a valid reason, but it may mean that the person selling may not have any knowledge about the generator.
From a Tool Rental Store
Used generators can also be sourced from local power tool/machine rental stores. You’ll find that if they repair generators they also will have a small selection for sale. The benefit of buying a portable generator here is that some warranty will be added. It may only be 30 – 90 days but you won’t get any warranty from a private seller.
The other benefit is it will likely have been serviced. The negative aspect of buying from a store is that the history of the generator may be unknown.
Generally tool rental stores have a good selection of used but serviced ex rental kit at good prices.
Generator Buyers Checklist (What to look for)
Nearly all portable generators are 4 stroke engines with an alternator attached (on the electric side). The majority of them run on gas. When you go to view the one you’ll have to use your visual smarts. It’s unlikely (but not impossible) that the seller will allow you to take a spanner to it. So this is a list of the things to look for.
Overall Look of the Generator
Take an overall view of the machine. Does it look well cared for? A few chips in the paintwork or dings are not going to affect how it runs.
But is the rust excessive?
This is not a good sign, rust suggests it has lived outdoors for the majority of its life, faded paint is also a sign that it has spent time in exposed sun.
Check for loose, missing, or broken elements. Because of the nature of the generator, there is sure to be some rattles and looseness in the body.
Worn out rubber engine mounts are common and not a deal breaker. They are easily replaced and for just a few dollars.
Many gas tanks are metal. A good observation is to shine a light into the tank. You’re looking for any kind of debris, either floating or at the bottom. Rust particles, if there’s a lot rust in your tank, then there’s rust in your carb. That’s not to say it’s not worth buying but you may have to replace the carb (approx $70). If you don’t think this is something you could do yourself then I’d walk away.
Water residue or droplets is another cause for concern. Water is never good and suggests a stabilizer has not been added to the gas.
Next check the oil. Ideally, it would be a golden color but a darker color is fine too and the level should be correct. If the oil is very dark, or grey or water-thin, then the generator has not been serviced recently. If you can smell gas from the dipstick it suggests that you may have a carb leak.
This oil is fine, while dark, it’s not black and you can clearly see how it coats the dipstick nicely and has a thick vicious quality.
Tags and Plates
This is where your personal use of the generator comes into play. Each generator will have a tag that tells the power output of the machine and the age of the machine. Make sure you’re buying a machine that suits your needs.
Although the generator may be old if it has been well maintained and looked after there’s no reason not to buy it.
Some larger generators may be electric start and if that’s the case the battery age may need to be checked. A battery will last about 2 – 4 years depending on how the generator is stored over winter.
The battery itself may have a year of manufacture stamped, but if not let the generator tag year be a guide.
If the tag suggests a 4 year or older machine, you may need to replace the battery in the near future. Some generators have hour meters – an account of worked hours – but not all have one.
Start it Up
If all is going smoothly at the viewing, the next step is to start it up. Most have a pull start but as said, some have an electric push start. It should start on the second or third pull. But if a generator is warm when you arrive then the seller has had it running.
Not usually a good sign. Cold start is always the best way to judge if a machine is in great shape. It should run smoothly, without any large plooms of blue/white smoke and without surging.
Check Your Outlets
If the start is good then the next check is the outlets. A generator can run all day without any problems but the real true test is will it run under a load. Most machines have 2 – 4 outlets and some now have USB ports. Check all outlets are working. The best item to bring along with you to viewing is a hairdryer (I would say a kettle, but then you need water, and it can get messy…) I pick either of these as they have an element.
Anything that has an element will put a high load on the generator and will show if it is up to par or not.
A single outlet not working is not that expensive to swap out but it is electric, so unless you’re qualified to do this work, I’d bring it to a shop. More than one outlet not working and I’d leave it behind.
Check the Brand
The last thing we’ll look at is the brand. You can’t be too choosy when selecting from used stock. What I’d advise is to check out what is on offer online, new, and get a good idea of what your needs are and which one would suit you best. Then you can start looking for this brand as a used machine.
The cost of a used generator should be about 40% of a new one. This being said, all brands cost different amounts, from inexpensive to spendy for the absolute best.
The best brands to research are Honda, Kohler, John Deere, or Champion. Again it depends what your needs are, Champion offers small campsite versions that you can stack together but Honda is the ultimate small engine machine.
|Portable AC Generator||Average Cost||Portable Inverter Genrator||Average Cost|
|John Deere||$700||John Deere||$1100|
Buying a used generator is a good idea but not something to buy in a hurry. Do your research and make sure it’s powerful enough for your job. Check the problems and bring a hairdryer!
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John Cunningham is an Automotive Technician and writer at Lawnmowerfixed.com.
He’s been a mechanic for over twenty-five years and shares his know-how and hands-on experience in our DIY repair guides.
Johns’s fluff-free How-to guides help homeowners fix lawnmowers, tractor mowers, chainsaws, leaf blowers, power washers, generators, snow blowers, and more.