Guide to Purchasing a Used Generator

Buying a used generator will save you up to 50% of the price of a new unit, but it does bear some risks. This guide highlights some important things to consider when looking for a used generator at a great price.

1. Start with analyzing your needs

How much power?

It’s extremely important to calculate your wattage needs precisely and be sure the used generator you’re buying has the right amount of power. It’s recommended to leave this task in the hands of a certified electrician, but you could also do it yourself. Just be sure to give it your full attention, as both under- and oversizing have their consequences.

The first step is to make a list of all the appliances the used generator will have to power, their running and start up consumption. You can find them in the instruction manuals; on the nameplates or online if you know the brand and model of the electronics. If the list includes pumps, fans, air conditioners and other machinery with a lot of moving parts in them, you’ll notice that their start up requirements are 3-5 times higher than the operating. Add up all the running values, the highest start up one and put another 20% on top. The extra capacity will be useful in the event you get some more equipment between the purchase and the next blackout- for example a new security system or medical gear.

Individual needs do vary, but the general rule is 3-7KW for an RV, 5-50KW for a house, 30- 3MW for a business building or factory.

Portable or standby?

This is a relatively easy question to answer. If you’re going to take the used generator on your camping trips or use it to provide energy for some other activities that require frequent change of location, a portable unit is the way to go. For all other cases, a standby genset will get the job done.

2. What features do you want your used generator to have?

Just because you’re shopping second hand doesn’t mean you can’t have all the modern functions you want. There are a lot of newer models available that have been discarded from their owners simply because they wanted to upgrade on some parameters. Whether you’re interested in buying a basic or a more sophisticated used generator, there are functions that should not be ignored. Most of them are safety related and listed below.

A transfer switch can prevent the genset from back feeding the power circuit and possibly injuring you, your family members and utility workers performing maintenance on your lines. You’ll have to decide between the automatic and the manual option. An automatic will detect the main supply go off and on, and will ensure an uninterrupted power flow without you having to be there to turn the motor on. A manual one will require your presence to change from one energy source to another.

Automatic safety shut down is the next thing you may want to consider. Sensors will monitor for unsafe operating conditions that may lead to dangerous malfunctions. If any of the kind is detected, the used generator will shut down on its own.

Cooling systems are air or liquid operated. Although air-cooled units are cheaper and lighter, they tend to be noisier and need more maintenance. A liquid-cooled used generator will cost a bit more, but will be more reliable in the long run.

Noise levels  are often a concern when buying a used generator. Never forget to inform yourself on the matter, because apart from annoying, a loud motor is also unhealthy. Try to get a quiet unit- this translates into no more than 65-70 decibels, if you go to 78 or above you risk hearing damage.

3. What fuel to use?

Portable units are almost always gasoline-powered, but with standbys you get to choose between diesel, gasoline and propane. Each of the three has its upsides and downsides, so if you find it hard to make up your mind, you could opt for a dual or tri-fuel used generator.

Diesel is typically considered to be the most energy efficient, but such units are somewhat noisier and more pricey to maintain.

Gasoline stands for the best initial and running costs, but it also has the highest greenhouse gasses exhaust and shortest shelf life up to 12 months.

Propane might have the smallest power output, but it is the cleanest burning fossil fuel. Even Biodiesel is not as eco-friendly. Its other main advantage is the fact that if stored properly, propane lasts virtually forever.

4. Where to shop?

Your first idea should be a refurbished genset sold by the manufacturer or a recommended retailer. Customers often send back their old units to the producer in return for a discount on a newer model. Such motors are thoroughly tested, all worn out parts get replaced and by the time the reconditioning process is over, you will be left with a perfectly working used generator.

The internet is the next place to search, where you can find lots of residential and industrial generators for sale. The reason e-stores are getting more and more popular is that they offer great deals and discounts.

Hit the second hand electronics shops. You’ll find all sorts of equipment and could probably bargain for a discount.

5. Ask for the history of the used generator and inspect it if possible

It makes sense that if a motor has only been used as backup and has small “mileage” behind its back, it should be in a better overall condition than one that has been constantly exploited. In case such info is not available, check the odometer of the unit; at least that way you’ll know how many hours it’s worked.

Actually seeing and inspecting the used generator before buying it reduces the risk of the purchase. Don’t be afraid to check out the unit yourself, or better yet, bring along an electrician to do that for you. If you’re going to do it on your own, make sure to examine all the belts and bolts for cracks and fraying, the fuel lines for stains or leaks, and if the used generator is air-cooled take a look at the filters as well.

6. Don’t skip the warranty

Warranty might save you a lot of nerves and money in the long run. This is especially true if the used generator you’re considering is an older model, for which spare parts are hard to come by.

So that’s it. Now you have the necessary knowledge to buy a used generator that will keep your important devices powered up during a blackout or on a trip.

Yet, if you decide to purchase a new generator, also consider different generator financing options that different companies provide.