A generator is one of the single best preps you can have, for virtually any disaster situation.
Whether you have a small, portable generator capable of running and appliance or two and a handful of tools or a large, built-in standby generator that can power your entire house with capacity to spare, you’ll be able to keep the lights on when no one else can.
However, a generator is only helpful so long as it is running. How long can you continuously run a generator for?
A small, portable generator might only run for 24 to 72 hours with constant refueling while larger standby generators can run for 200-300 hours so long as their fuel supply holds.
The type of fuel that a generator uses along with the quantity of the connected fuel supply, rating of the generator, general state of repair and other factors all play a part in determining how long you can safely keep your genny running.
Overworking a generator is a great way to damage or destroy it, plunging you back into the darkness and back to square one as far as your personal power infrastructure is concerned.
A more thorough understanding of the various factors associated with generator uptime will help you make an informed decision for both equipping yourself with a generator and making best use of it. We will discuss these factors below.
Warning: Most Generators Won’t Run Indefinitely!
Before we go any further, it is essential that all preppers understand most generators are incapable of running indefinitely, despite the fuel supply that you might have on hand.
Planning to simply kick on your generator after the lights go out and carry on living as usual for the duration, heedless of any hardware limitations.
Doing so is a great way to damage your generator. You definitely can’t afford that in the middle of a survival situation when you are depending on it.
It is imperative that you read and understand the manual and any other associated technical literature included with your generator to avoid this unhappy occurrence.
Fuel Supply and Type of Fuel
The type of fuel that you’re generator uses will play a part in determining it’s useful up time. Two of the most common and popular fuel types for generators today are gasoline and propane.
Both are highly energetic, both are generally efficient, but gasoline has a decided limitation and that the generator cannot be safely refueled once it has gotten hot should it run out of fuel.
Doing so might risk a calamitous fuel explosion at worst or an out of control fire at best. You can afford neither during a live event.
The nature of propane generators usually means they will be hooked up to a larger, on site tank with a large capacity meaning that refueling is more of a logistical than a practical concern.
However, some smaller, portable generators use propane and can be fed from common barbecue cylinders.
For most models, these can be switched out even when the generator is hot so long as it has been shut down with little if any risk of mishap so long as correct procedures are followed.
Whichever kind of fuel you are using, the larger the attached fuel supply the longer the generator should be able to run theoretically before it needs to be shut down.
The rating or size of the generator is another major determining factor in uptime, with larger generators almost invariably capable of running far longer than smaller, portable jobs. To a lesser extent, the nature of the generator also has a part to play in determining runtime.
A massive standby generator, or bank of generators, intended to operate a hospital or any other vital equipment in the event of a power outage made likely run for days or even weeks at a time depending on the requirements of the facility assuming of course that the generators in a good state of repair and has adequate fuel.
A small, wheeled job site generator may only be good for several hours before it needs to be shut down.
Somewhere in the middle is a household standby generator, which might run anywhere from a day to a week at a time. This is where many people can go wrong by assuming that the generator can run indefinitely so long as it is fueled.
Heat buildup is a major enemy of generator performance, and is one of the chief limiting factors concerning runtime.
All generators build up plenty of waste heat as they operate, and depending on ambient conditions, the efficiency of the generator and other factors this waste heat could continually climb, and climb past safe operating limits.
When the temperature rises too high, a decision must be made. Some generators feature a built-in automatic shutdown switch activated when temperatures climb too high, whereas other generators must be manually shut down.
Many generators can continue to operate outside of their nominal heat range, but this usually comes at the cost of accelerated wear and the potential for catastrophic breakdown.
It must be noted that ambient temperature greatly determines how much excess heat will build up and how quickly.
Running a generator in a frigid climate will go a long way towards mitigating this excess heat, whereas running one in a steamy, arid environment will exacerbate the problem. Don’t forget to factor local conditions into your calculations!
State of Repair
the state of repair a generator is in also greatly determines it’s run time, and a generator that is kept in tip top shape will run longer, easier and more reliably than one that is in a rough and ramshackle condition.
Generators in a poor state of repair might have a decidedly reduced operational time that could come back to bite you in the butt when you can least afford such a setback.
Additionally, the vintage of the generator plays a part in this calculation, with newer, state-of-the-art generators benefiting greatly from enhancements in materials, design and management systems whereas older generators are usually simpler but far less refined and more likely to have limited operational capacity.
Both might be entirely adequate to your needs, even far more than adequate, but you must know what you are dealing with.
It should go without saying that regular maintenance checks should be performed on your generator, and many manufacturers prescribe simple inspection or other maintenance protocols after running the generator for so many hours or so many tanks worth of fuel.
Don’t ignore these recommendations! The corporations that produce these devices have high dollar teams of engineers that design and refine them, and they have put in the work to determine what a generator is capable of and, just as importantly, what it requires in terms of maintenance for long life and consistent operation.
Most generators can run for quite a long time, but they cannot run forever, and operational time can be measured in as little as a handful of hours to as long as weeks on end without shutting down.
Uptime is affected by many factors, including the rating and fuel type of the generator along with its state of repair, overall condition and accessible fuel supply.
A thorough understanding of what your generator is capable of under various conditions is essential for getting the most out of it when the chips are down.
Tom Marlowe practically grew up with a gun in his hand, and has held all kinds of jobs in the gun industry: range safety, sales, instruction and consulting, Tom has the experience to help civilian shooters figure out what will work best for them.